Revert Bug 330707 - Add optional support for MarkDown

30 files changed, 49 insertions, 1135 deletions

diff --git a/Bugzilla.pm b/Bugzilla.pm
index 048e72d48..c3f5780b0 100644
--- a/Bugzilla.pm
+++ b/Bugzilla.pm
@@ -397,13 +397,6 @@ sub logout_request {
     # there. Don't rely on it: use Bugzilla->user->login instead!
 }
 
-sub markdown {
-    return if !Bugzilla->feature('markdown');
-
-    require Bugzilla::Markdown;
-    return $_[0]->request_cache->{markdown} ||= Bugzilla::Markdown->new();
-}
-
 sub job_queue {
     require Bugzilla::JobQueue;
     return $_[0]->request_cache->{job_queue} ||= Bugzilla::JobQueue->new();
@@ -954,10 +947,6 @@ Returns the local timezone of the Bugzilla installation,
 as a DateTime::TimeZone object. This detection is very time
 consuming, so we cache this information for future references.
 
-=item C<markdown>
-
-The current L<Markdown|Bugzilla::Markdown> object, to be used for Markdown rendering.
-
 =item C<job_queue>
 
 Returns a L<Bugzilla::JobQueue> that you can use for queueing jobs.
diff --git a/Bugzilla/Bug.pm b/Bugzilla/Bug.pm
index aec7c1e82..7b97d1ff8 100644
--- a/Bugzilla/Bug.pm
+++ b/Bugzilla/Bug.pm
@@ -694,8 +694,6 @@ sub create {
       unless defined $params->{rep_platform};
     # Make sure a comment is always defined.
     $params->{comment} = '' unless defined $params->{comment};
-    $params->{is_markdown} = 0
-      unless defined $params->{is_markdown} && $params->{is_markdown} eq '1';
 
     $class->check_required_create_fields($params);
     $params = $class->run_create_validators($params);
@@ -709,7 +707,6 @@ sub create {
     my $blocked          = delete $params->{blocked};
     my $keywords         = delete $params->{keywords};
     my $creation_comment = delete $params->{comment};
-    my $is_markdown      = delete $params->{is_markdown};
     my $see_also         = delete $params->{see_also};
 
     # We don't want the bug to appear in the system until it's correctly
@@ -797,7 +794,6 @@ sub create {
 
     # We now have a bug id so we can fill this out
     $creation_comment->{'bug_id'} = $bug->id;
-    $creation_comment->{'is_markdown'} = $is_markdown;
 
     # Insert the comment. We always insert a comment on bug creation,
     # but sometimes it's blank.
@@ -2430,8 +2426,7 @@ sub set_all {
         # there are lots of things that want to check if we added a comment.
         $self->add_comment($params->{'comment'}->{'body'},
             { isprivate => $params->{'comment'}->{'is_private'},
-              work_time => $params->{'work_time'},
-              is_markdown => $params->{'comment'}->{'is_markdown'} });
+              work_time => $params->{'work_time'} });
     }
 
     if (exists $params->{alias} && $params->{alias}{set}) {
diff --git a/Bugzilla/Comment.pm b/Bugzilla/Comment.pm
index 3dabe6702..c235b8d30 100644
--- a/Bugzilla/Comment.pm
+++ b/Bugzilla/Comment.pm
@@ -43,7 +43,6 @@ use constant DB_COLUMNS => qw(
     already_wrapped
     type
     extra_data
-    is_markdown
 );
 
 use constant UPDATE_COLUMNS => qw(
@@ -66,7 +65,6 @@ use constant VALIDATORS => {
     work_time   => \&_check_work_time,
     thetext     => \&_check_thetext,
     isprivate   => \&_check_isprivate,
-    is_markdown => \&Bugzilla::Object::check_boolean,
     extra_data  => \&_check_extra_data,
     type        => \&_check_type,
 };
@@ -179,7 +177,6 @@ sub body        { return $_[0]->{'thetext'};   }
 sub bug_id      { return $_[0]->{'bug_id'};    }
 sub creation_ts { return $_[0]->{'bug_when'};  }
 sub is_private  { return $_[0]->{'isprivate'}; }
-sub is_markdown { return $_[0]->{'is_markdown'}; }
 sub work_time   {
     # Work time is returned as a string (see bug 607909)
     return 0 if $_[0]->{'work_time'} + 0 == 0;
@@ -277,7 +274,6 @@ sub body_full {
 sub set_is_private  { $_[0]->set('isprivate',  $_[1]); }
 sub set_type        { $_[0]->set('type',       $_[1]); }
 sub set_extra_data  { $_[0]->set('extra_data', $_[1]); }
-sub set_is_markdown { $_[0]->set('is_markdown', $_[1]); }
 
 sub add_tag {
     my ($self, $tag) = @_;
@@ -526,10 +522,6 @@ C<string> Time spent as related to this comment.
 
 C<boolean> Comment is marked as private.
 
-=item C<is_markdown>
-
-C<boolean> Whether this comment needs L<Markdown|Bugzilla::Markdown> rendering to be applied.
-
 =item C<already_wrapped>
 
 If this comment is stored in the database word-wrapped, this will be C<1>.
@@ -625,16 +617,6 @@ A string, the full text of the comment as it would be displayed to an end-user.
 
 =cut
 
-=head2 Modifiers
-
-=over
-
-=item C<set_is_markdown>
-
-Sets whether this comment needs L<Markdown|Bugzilla::Markdown> rendering to be applied.
-
-=back
-
 =head1 B<Methods in need of POD>
 
 =over
diff --git a/Bugzilla/Constants.pm b/Bugzilla/Constants.pm
index 4c1f11003..4f5ec581d 100644
--- a/Bugzilla/Constants.pm
+++ b/Bugzilla/Constants.pm
@@ -193,8 +193,6 @@ use Memoize;
     AUDIT_REMOVE
 
     MOST_FREQUENT_THRESHOLD
-
-    MARKDOWN_TAB_WIDTH
 );
 
 @Bugzilla::Constants::EXPORT_OK = qw(contenttypes);
@@ -637,10 +635,6 @@ use constant AUDIT_REMOVE => '__remove__';
 # on the "Most frequently reported bugs" page.
 use constant MOST_FREQUENT_THRESHOLD => 2;
 
-# The number of spaces used to represent each tab character
-# by Markdown engine
-use constant MARKDOWN_TAB_WIDTH => 2;
-
 sub bz_locations {
     # Force memoize() to re-compute data per project, to avoid
     # sharing the same data across different installations.
diff --git a/Bugzilla/DB/Schema.pm b/Bugzilla/DB/Schema.pm
index ebe2cb426..d1c1dc7e9 100644
--- a/Bugzilla/DB/Schema.pm
+++ b/Bugzilla/DB/Schema.pm
@@ -410,8 +410,7 @@ use constant ABSTRACT_SCHEMA => {
                                 DEFAULT => 'FALSE'},
             type            => {TYPE => 'INT2', NOTNULL => 1,
                                 DEFAULT => '0'},
-            extra_data      => {TYPE => 'varchar(255)'},
-            is_markdown     => {TYPE => 'BOOLEAN', NOTNULL => 1, DEFAULT => 'FALSE'}
+            extra_data      => {TYPE => 'varchar(255)'}
         ],
         INDEXES => [
             longdescs_bug_id_idx   => [qw(bug_id work_time)],
diff --git a/Bugzilla/Install.pm b/Bugzilla/Install.pm
index 5a2266e36..07bc9d6c3 100644
--- a/Bugzilla/Install.pm
+++ b/Bugzilla/Install.pm
@@ -90,8 +90,6 @@ sub SETTINGS {
     bugmail_new_prefix => { options => ['on', 'off'], default => 'on' },
     # 2013-07-26 joshi_sunil@in.com -- Bug 669535
     possible_duplicates => { options => ['on', 'off'], default => 'on' },
-    # 2014-05-24 koosha.khajeh@gmail.com -- Bug 1014164
-    use_markdown       => { options => ['on', 'off'], default => 'on' },
     }
 };
 
diff --git a/Bugzilla/Install/DB.pm b/Bugzilla/Install/DB.pm
index ab02fe41d..8ffde11fd 100644
--- a/Bugzilla/Install/DB.pm
+++ b/Bugzilla/Install/DB.pm
@@ -726,10 +726,6 @@ sub update_table_definitions {
     # 2014-08-11 sgreen@redhat.com - Bug 1012506
      _update_alias();
 
-    # 2014-08-14 koosha.khajeh@gmail.com - Bug 330707
-    $dbh->bz_add_column('longdescs', 'is_markdown',
-                        {TYPE => 'BOOLEAN', NOTNULL => 1, DEFAULT => 'FALSE'});
-
     ################################################################
     # New --TABLE-- changes should go *** A B O V E *** this point #
     ################################################################
diff --git a/Bugzilla/Install/Requirements.pm b/Bugzilla/Install/Requirements.pm
index db3d7b028..48e992db7 100644
--- a/Bugzilla/Install/Requirements.pm
+++ b/Bugzilla/Install/Requirements.pm
@@ -396,14 +396,6 @@ sub OPTIONAL_MODULES {
         version => '0',
         feature => ['memcached'],
     },
-
-    # Markdown
-    {
-        package => 'Text-Markdown',
-        module  => 'Text::Markdown',
-        version => '1.0.26',
-        feature => ['markdown'],
-    }
     );
 
     my $extra_modules = _get_extension_requirements('OPTIONAL_MODULES');
@@ -427,7 +419,6 @@ use constant FEATURE_FILES => (
                       'Bugzilla/JobQueue/*', 'jobqueue.pl'],
     patch_viewer  => ['Bugzilla/Attachment/PatchReader.pm'],
     updates       => ['Bugzilla/Update.pm'],
-    markdown      => ['Bugzilla/Markdown.pm'],
     memcached     => ['Bugzilla/Memcache.pm'],
 );
 
diff --git a/Bugzilla/Markdown.pm b/Bugzilla/Markdown.pm
deleted file mode 100644
index 353c2ff6a..000000000
--- a/Bugzilla/Markdown.pm
+++ /dev/null
@@ -1,520 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-#
-# This Source Code Form is "Incompatible With Secondary Licenses", as
-# defined by the Mozilla Public License, v. 2.0.
-
-package Bugzilla::Markdown;
-
-use 5.10.1;
-use strict;
-use warnings;
-
-use Bugzilla::Constants;
-use Bugzilla::Template;
-
-use Digest::MD5 qw(md5_hex);
-
-use parent qw(Text::Markdown);
-
-@Bugzilla::Markdown::EXPORT = qw(new);
-
-# Regex to match balanced [brackets]. See Friedl's
-# "Mastering Regular Expressions", 2nd Ed., pp. 328-331.
-our ($g_nested_brackets, $g_nested_parens);
-$g_nested_brackets = qr{
-    (?>                                 # Atomic matching
-       [^\[\]]+                         # Anything other than brackets
-     |
-       \[
-         (??{ $g_nested_brackets })     # Recursive set of nested brackets
-       \]
-    )*
-}x;
-# Doesn't allow for whitespace, because we're using it to match URLs:
-$g_nested_parens = qr{
-    (?>                                 # Atomic matching
-       [^()\s]+                            # Anything other than parens or whitespace
-     |
-       \(
-         (??{ $g_nested_parens })        # Recursive set of nested brackets
-       \)
-    )*
-}x;
-
-our %g_escape_table;
-foreach my $char (split //, '\\`*_{}[]()>#+-.!~') {
-    $g_escape_table{$char} = md5_hex($char);
-}
-$g_escape_table{'&lt;'} = md5_hex('&lt;');
-
-sub new {
-    my $invocant = shift;
-    my $class = ref $invocant || $invocant;
-    return $class->SUPER::new(tab_width => MARKDOWN_TAB_WIDTH,
-                              # Bugzilla uses HTML not XHTML
-                              empty_element_suffix => '>');
-}
-
-sub markdown {
-    my $self = shift;
-    my $text = shift;
-    my $user = Bugzilla->user;
-
-    if ($user->settings->{use_markdown}->{is_enabled}
-        && $user->setting('use_markdown') eq 'on')
-    {
-        return $self->SUPER::markdown($text, @_);
-    }
-
-    return Bugzilla::Template::quoteUrls($text);
-}
-
-sub _Markdown {
-    my $self = shift;
-    my $text = shift;
-
-    $text = Bugzilla::Template::quoteUrls($text, undef, undef, undef, undef, 1);
-
-    return $self->SUPER::_Markdown($text, @_);
-}
-
-sub _RunSpanGamut {
-    # These are all the transformations that occur *within* block-level
-    # tags like paragraphs, headers, and list items.
-
-    my ($self, $text) = @_;
-
-    $text = $self->_DoCodeSpans($text);
-    $text = $self->_EscapeSpecialCharsWithinTagAttributes($text);
-    $text = $self->_EscapeSpecialChars($text);
-
-    $text = $self->_DoAnchors($text);
-
-    # Strikethroughs is Bugzilla's extension
-    $text = $self->_DoStrikethroughs($text);
-
-    $text = $self->_DoAutoLinks($text);
-    $text = $self->_EncodeAmpsAndAngles($text);
-    $text = $self->_DoItalicsAndBold($text);
-
-    $text =~ s/\n/<br$self->{empty_element_suffix}\n/g;
-
-    return $text;
-}
-
-# Override to check for HTML-escaped <>" chars.
-sub _StripLinkDefinitions {
-#
-# Strips link definitions from text, stores the URLs and titles in
-# hash references.
-#
-    my ($self, $text) = @_;
-    my $less_than_tab = $self->{tab_width} - 1;
-
-    # Link defs are in the form: ^[id]: url "optional title"
-    while ($text =~ s{
-            ^[ ]{0,$less_than_tab}\[(.+)\]: # id = \$1
-              [ \t]*
-              \n?               # maybe *one* newline
-              [ \t]*
-            (?:&lt;)?<a\s+href="(.+?)">\2</a>(?:&gt;)?          # url = \$2
-              [ \t]*
-              \n?               # maybe one newline
-              [ \t]*
-            (?:
-                (?<=\s)         # lookbehind for whitespace
-                (?:&quot;|\()
-                (.+?)           # title = \$3
-                (?:&quot;|\))
-                [ \t]*
-            )?  # title is optional
-            (?:\n+|\Z)
-        }{}omx) {
-        $self->{_urls}{lc $1} = $self->_EncodeAmpsAndAngles( $2 );    # Link IDs are case-insensitive
-        if ($3) {
-            $self->{_titles}{lc $1} = $3;
-            $self->{_titles}{lc $1} =~ s/"/&quot;/g;
-        }
-
-    }
-
-    return $text;
-}
-
-# We need to look for HTML-escaped '<' and '>' (i.e. &lt; and &gt;).
-# We also remove Email linkification from the original implementation
-# as it is already done in Bugzilla's quoteUrls().
-sub _DoAutoLinks {
-    my ($self, $text) = @_;
-
-    $text =~ s{(?:<|&lt;)((?:https?|ftp):[^'">\s]+?)(?:>|&gt;)}{<a href="$1">$1</a>}gi;
-    return $text;
-}
-
-# The main reasons for overriding this method are
-# resolving URL conflicts with Bugzilla's quoteUrls()
-# and also changing '"' to '&quot;' in regular expressions wherever needed.
-sub _DoAnchors {
-#
-# Turn Markdown link shortcuts into <a> tags.
-#
-    my ($self, $text) = @_;
-
-    # We revert linkifications of non-email links and only
-    # those links whose URL and title are the same because
-    # this way we can be sure that link is generated by quoteUrls()
-    $text =~ s@<a \s+ href="(?! mailto ) (.+?)">\1</a>@$1@xmg;
-
-    #
-    # First, handle reference-style links: [link text] [id]
-    #
-    $text =~ s{
-        (                   # wrap whole match in $1
-          \[
-            ($g_nested_brackets)    # link text = $2
-          \]
-
-          [ ]?              # one optional space
-          (?:\n[ ]*)?       # one optional newline followed by spaces
-
-          \[
-            (.*?)       # id = $3
-          \]
-        )
-    }{
-        my $whole_match = $1;
-        my $link_text   = $2;
-        my $link_id     = lc $3;
-
-        if ($link_id eq "") {
-            $link_id = lc $link_text;   # for shortcut links like [this][].
-        }
-
-        $link_id =~ s{[ ]*\n}{ }g; # turn embedded newlines into spaces
-
-        $self->_GenerateAnchor($whole_match, $link_text, $link_id);
-    }xsge;
-
-    #
-    # Next, inline-style links: [link text](url "optional title")
-    #
-    $text =~ s{
-        (               # wrap whole match in $1
-          \[
-            ($g_nested_brackets)    # link text = $2
-          \]
-          \(            # literal paren
-            [ \t]*
-            ($g_nested_parens)   # href = $3
-            [ \t]*
-            (           # $4
-              (&quot;|')    # quote char = $5
-              (.*?)     # Title = $6
-              \5        # matching quote
-              [ \t]*    # ignore any spaces/tabs between closing quote and )
-            )?          # title is optional
-          \)
-        )
-    }{
-        my $result;
-        my $whole_match = $1;
-        my $link_text   = $2;
-        my $url         = $3;
-        my $title       = $6;
-
-        # Remove Bugzilla quoteUrls() linkification
-        if ($url =~ /^a href="/ && $url =~ m|</a$|) {
-            $url =~ s/^[^>]+>//;
-            $url =~ s@</a$@@;
-        }
-
-        # Limit URL to HTTP/HTTPS links
-        $url = "http://$url" unless $url =~ m!^https?://!i;
-
-        $self->_GenerateAnchor($whole_match, $link_text, undef, $url, $title);
-    }xsge;
-
-    #
-    # Last, handle reference-style shortcuts: [link text]
-    # These must come last in case you've also got [link test][1]
-    # or [link test](/foo)
-    #
-    $text =~ s{
-        (                    # wrap whole match in $1
-          \[
-            ([^\[\]]+)        # link text = $2; can't contain '[' or ']'
-          \]
-        )
-    }{
-        my $result;
-        my $whole_match = $1;
-        my $link_text   = $2;
-        (my $link_id = lc $2) =~ s{[ ]*\n}{ }g; # lower-case and turn embedded newlines into spaces
-
-        $self->_GenerateAnchor($whole_match, $link_text, $link_id);
-    }xsge;
-
-    return $text;
-}
-
-# The purpose of overriding this function is to add support
-# for a Github Flavored Markdown (GFM) feature called 'Multiple
-# underscores in words'. The standard markdown specification
-# specifies the underscore for making the text emphasized/bold.
-# However, some variable names in programming languages contain underscores
-# and we do not want a part of those variables to look emphasized/bold.
-# Instead, we render them as the way they originally are.
-sub _DoItalicsAndBold {
-    my ($self, $text) = @_;
-
-    # Handle at beginning of lines:
-    $text =~ s{ (^__ (?=\S) (.+?[*_]*) (?<=\S) __ (?!\S)) }
-              {
-                  my $result = _has_multiple_underscores($2) ? $1 : "<strong>$2</strong>";
-                  $result;
-              }gsxe;
-
-    $text =~ s{ ^\*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{<strong>$1</strong>}gsx;
-
-    $text =~ s{ (^_ (?=\S) (.+?) (?<=\S) _ (?!\S)) }
-              {
-                  my $result = _has_multiple_underscores($2) ? $1 : "<em>$2</em>";
-                  $result;
-              }gsxe;
-
-    $text =~ s{ ^\* (?=\S) (.+?) (?<=\S) \* }{<em>$1</em>}gsx;
-
-    # <strong> must go first:
-    $text =~ s{ ( (?<=\W) __ (?=\S) (.+?[*_]*) (?<=\S) __ (?!\S) ) }
-              {
-                  my $result = _has_multiple_underscores($2) ? $1 : "<strong>$2</strong>";
-                  $result;
-              }gsxe;
-
-
-    $text =~ s{ (?<=\W) \*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{<strong>$1</strong>}gsx;
-
-    $text =~ s{ ( (?<=\W) _ (?=\S) (.+?) (?<=\S) _ (?!\S) ) }
-              {
-                  my $result = _has_multiple_underscores($2) ? $1 : "<em>$2</em>";
-                  $result;
-              }gsxe;
-
-    $text =~ s{ (?<=\W) \* (?=\S) (.+?) (?<=\S) \* }{<em>$1</em>}gsx;
-
-    # And now, a second pass to catch nested strong and emphasis special cases
-    $text =~ s{ ( (?<=\W) __ (?=\S) (.+?[*_]*) (?<=\S) __ (\S*) ) }
-              {
-                  my $result = _has_multiple_underscores($3) ? $1 : "<strong>$2</strong>$3";
-                  $result;
-              }gsxe;
-
-    $text =~ s{ (?<=\W) \*\* (?=\S) (.+?[*_]*) (?<=\S) \*\* }{<strong>$1</strong>}gsx;
-    $text =~ s{ ( (?<=\W) _ (?=\S) (.+?) (?<=\S) _ (\S*) ) }
-              {
-                  my $result = _has_multiple_underscores($3) ? $1 : "<em>$2</em>$3";
-                  $result;
-              }gsxe;
-
-    $text =~ s{ (?<=\W) \* (?=\S) (.+?) (?<=\S) \* }{<em>$1</em>}gsx;
-
-    return $text;
-}
-
-sub _DoStrikethroughs {
-    my ($self, $text) = @_;
-
-    $text =~ s{ ^ ~~ (?=\S) ([^~]+?) (?<=\S) ~~ (?!~) }{<del>$1</del>}gsx;
-    $text =~ s{ (?<=_|[^~\w]) ~~ (?=\S) ([^~]+?) (?<=\S) ~~ (?!~) }{<del>$1</del>}gsx;
-
-    return $text;
-}
-
-# The original _DoCodeSpans() uses the 's' modifier in its regex
-# which prevents _DoCodeBlocks() to match GFM fenced code blocks.
-# We copy the code from the original implementation and remove the
-# 's' modifier from it.
-sub _DoCodeSpans {
-    my ($self, $text) = @_;
-
-    $text =~ s@
-            (?<!\\)     # Character before opening ` can't be a backslash
-            (`+)        # $1 = Opening run of `
-            (.+?)       # $2 = The code block
-            (?<!`)
-            \1          # Matching closer
-            (?!`)
-        @
-             my $c = "$2";
-             $c =~ s/^[ \t]*//g; # leading whitespace
-             $c =~ s/[ \t]*$//g; # trailing whitespace
-             $c = $self->_EncodeCode($c);
-            "<code>$c</code>";
-        @egx;
-
-    return $text;
-}
-
-# Override to add GFM Fenced Code Blocks
-sub _DoCodeBlocks {
-    my ($self, $text) = @_;
-
-    $text =~ s{
-        ^ `{3,} [\s\t]* \n
-        (                # $1 = the entire code block
-          (?: .* \n+)+?
-        )
-        `{3,} [\s\t]* $
-        }{
-            my $codeblock = $1;
-            my $result;
-
-            $codeblock = $self->_EncodeCode($codeblock);
-            $codeblock = $self->_Detab($codeblock);
-            $codeblock =~ s/\n\z//; # remove the trailing newline
-
-            $result = "\n\n<pre><code>" . $codeblock . "</code></pre>\n\n";
-            $result;
-        }egmx;
-
-    # And now do the standard code blocks
-    $text = $self->SUPER::_DoCodeBlocks($text);
-
-    return $text;
-}
-
-sub _DoBlockQuotes {
-    my ($self, $text) = @_;
-
-    $text =~ s{
-          (                             # Wrap whole match in $1
-            (?:
-              ^[ \t]*&gt;[ \t]?         # '>' at the start of a line
-                .+\n                    # rest of the first line
-              (?:.+\n)*                 # subsequent consecutive lines
-              \n*                       # blanks
-            )+
-          )
-        }{
-            my $bq = $1;
-            $bq =~ s/^[ \t]*&gt;[ \t]?//gm; # trim one level of quoting
-            $bq =~ s/^[ \t]+$//mg;          # trim whitespace-only lines
-            $bq = $self->_RunBlockGamut($bq, {wrap_in_p_tags => 1});      # recurse
-            $bq =~ s/^/  /mg;
-            # These leading spaces screw with <pre> content, so we need to fix that:
-            $bq =~ s{(\s*<pre>.+?</pre>)}{
-                        my $pre = $1;
-                        $pre =~ s/^  //mg;
-                        $pre;
-                    }egs;
-            "<blockquote>\n$bq\n</blockquote>\n\n";
-        }egmx;
-
-    return $text;
-}
-
-sub _EncodeCode {
-    my ($self, $text) = @_;
-
-    # We need to unescape the escaped HTML characters in code blocks.
-    # These are the reverse of the escapings done in Bugzilla::Util::html_quote()
-    $text =~ s/&lt;/</g;
-    $text =~ s/&gt;/>/g;
-    $text =~ s/&quot;/"/g;
-    $text =~ s/&#64;/@/g;
-    # '&amp;' substitution must be the last one, otherwise a literal like '&gt;'
-    # will turn to '>' because '&' is already changed to '&amp;' in Bugzilla::Util::html_quote().
-    # In other words, html_quote() will change '&gt;' to '&amp;gt;' and then we will
-    # change '&amp;gt' -> '&gt;' -> '>' if we write this substitution as the first one.
-    $text =~ s/&amp;/&/g;
-    $text =~ s{<a \s+ href="(?:mailto:)? (.+?)"> \1 </a>}{$1}xmgi;
-    $text = $self->SUPER::_EncodeCode($text);
-    $text =~ s/~/$g_escape_table{'~'}/go;
-    # Encode '&lt;' to prevent URLs from getting linkified in code spans
-    $text =~ s/&lt;/$g_escape_table{'&lt;'}/go;
-
-    return $text;
-}
-
-sub _EncodeBackslashEscapes {
-    my ($self, $text) = @_;
-
-    $text = $self->SUPER::_EncodeBackslashEscapes($text);
-    $text =~ s/\\~/$g_escape_table{'~'}/go;
-
-    return $text;
-}
-
-sub _UnescapeSpecialChars {
-    my ($self, $text) = @_;
-
-    $text = $self->SUPER::_UnescapeSpecialChars($text);
-    $text =~ s/$g_escape_table{'~'}/~/go;
-    $text =~ s/$g_escape_table{'&lt;'}/&lt;/go;
-
-    return $text;
-}
-
-# Check if the passed string is of the form multiple_underscores_in_a_word.
-# To check that, we first need to make sure that the string does not contain
-# any white-space. Then, if the string is composed of non-space chunks which
-# are bound together with underscores, the string has the desired form.
-sub _has_multiple_underscores {
-    my $string = shift;
-    return 0 unless defined($string) && length($string);
-    return 0 if $string =~ /[\t\s]+/;
-    return 1 if scalar (split /_/, $string) > 1;
-    return 0;
-}
-
-1;
-
-__END__
-
-=head1 NAME
-
-Bugzilla::Markdown - Generates HTML output from structured plain-text input.
-
-=head1 SYNOPSIS
-
- use Bugzilla::Markdown;
-
- my $markdown = Bugzilla::Markdown->new();
- print $markdown->markdown($text);
-
-=head1 DESCRIPTION
-
-Bugzilla::Markdown implements a Markdown engine that produces
-an HTML-based output from a given plain-text input.
-
-The majority of the implementation is done by C<Text::Markdown>
-CPAN module. It also applies the linkifications done in L<Bugzilla::Template>
-to the input resulting in an output which is a combination of both Markdown
-structures and those defined by Bugzilla itself.
-
-=head2 Accessors
-
-=over
-
-=item C<markdown>
-
-C<string> Produces an HTML-based output string based on the structures
-and format defined in the given plain-text input.
-
-=over
-
-=item B<Params>
-
-=over
-
-=item C<text>
-
-C<string> A plain-text string which includes Markdown structures.
-
-=back
-
-=back
-
-=back
diff --git a/Bugzilla/Template.pm b/Bugzilla/Template.pm
index 7ce1be72b..bb8ff3b74 100644
--- a/Bugzilla/Template.pm
+++ b/Bugzilla/Template.pm
@@ -148,11 +148,10 @@ sub get_format {
 # If you want to modify this routine, read the comments carefully
 
 sub quoteUrls {
-    my ($text, $bug, $comment, $user, $bug_link_func, $for_markdown) = @_;
+    my ($text, $bug, $comment, $user, $bug_link_func) = @_;
     return $text unless $text;
     $user ||= Bugzilla->user;
     $bug_link_func ||= \&get_bug_link;
-    $for_markdown ||= 0;
 
     # We use /g for speed, but uris can have other things inside them
     # (http://foo/bug#3 for example). Filtering that out filters valid
@@ -223,11 +222,10 @@ sub quoteUrls {
 
     $text = html_quote($text);
 
-    unless ($for_markdown) {
-        # Color quoted text
-        $text =~ s~^(&gt;.+)$~<span class="quote">$1</span >~mg;
-        $text =~ s~</span >\n<span class="quote">~\n~g;
-    }
+    # Color quoted text
+    $text =~ s~^(&gt;.+)$~<span class="quote">$1</span >~mg;
+    $text =~ s~</span >\n<span class="quote">~\n~g;
+
     # mailto:
     # Use |<nothing> so that $1 is defined regardless
     # &#64; is the encoded '@' character.
@@ -858,24 +856,6 @@ sub create {
                            1
                          ],
 
-            markdown => [ sub {
-                              my ($context, $bug, $comment, $user) = @_;
-                              return sub {
-                                  my $text = shift;
-                                  return unless $text;
-
-                                  if (Bugzilla->feature('markdown')
-                                      && ((ref($comment) eq 'HASH' && $comment->{is_markdown})
-                                         || (ref($comment) eq 'Bugzilla::Comment' && $comment->is_markdown)))
-                                  {
-                                      return Bugzilla->markdown->markdown($text);
-                                  }
-                                  return quoteUrls($text, $bug, $comment, $user);
-                              };
-                          },
-                          1
-                        ],
-
             bug_link => [ sub {
                               my ($context, $bug, $options) = @_;
                               return sub {
diff --git a/Bugzilla/User.pm b/Bugzilla/User.pm
index fa2674366..acedc65f2 100644
--- a/Bugzilla/User.pm
+++ b/Bugzilla/User.pm
@@ -632,14 +632,6 @@ sub is_bug_ignored {
     return (grep {$_->{'id'} == $bug_id} @{$self->bugs_ignored}) ? 1 : 0;
 }
 
-sub use_markdown {
-    my ($self, $comment) = @_;
-    return Bugzilla->feature('markdown')
-           && $self->settings->{use_markdown}->{is_enabled}
-           && $self->settings->{use_markdown}->{value} eq 'on'
-           && (!defined $comment || $comment->is_markdown);
-}
-
 ##########################
 # Saved Recent Bug Lists #
 ##########################
@@ -2631,12 +2623,6 @@ C<string> The current summary of the bug.
 Returns true if the user does not want email notifications for the
 specified bug ID, else returns false.
 
-=item C<use_markdown>
-
-Returns true if the user has set their preferences to use Markdown
-for rendering comments. If an optional C<comment> object is passed
-then it returns true if the comment has markdown enabled.
-
 =back
 
 =head2 Saved Recent Bug Lists
diff --git a/Bugzilla/WebService/Bug.pm b/Bugzilla/WebService/Bug.pm
index f50bb6aee..7c28b1d8d 100644
--- a/Bugzilla/WebService/Bug.pm
+++ b/Bugzilla/WebService/Bug.pm
@@ -331,9 +331,7 @@ sub render_comment {
     Bugzilla->switch_to_shadow_db();
     my $bug = $params->{id} ? Bugzilla::Bug->check($params->{id}) : undef;
 
-    my $markdown = $params->{markdown} ? 1 : 0;
-    my $tmpl = $markdown ? '[% text FILTER markdown(bug, { is_markdown => 1 }) %]' : '[% text FILTER markdown(bug) %]';
-
+    my $tmpl = '[% text FILTER quoteUrls(bug) %]';
     my $html;
     my $template = Bugzilla->template;
     $template->process(
@@ -352,16 +350,15 @@ sub _translate_comment {
                                                   : undef;
 
     my $comment_hash = {
-        id            => $self->type('int', $comment->id),
-        bug_id        => $self->type('int', $comment->bug_id),
-        creator       => $self->type('email', $comment->author->login),
-        time          => $self->type('dateTime', $comment->creation_ts),
+        id         => $self->type('int', $comment->id),
+        bug_id     => $self->type('int', $comment->bug_id),
+        creator    => $self->type('email', $comment->author->login),
+        time       => $self->type('dateTime', $comment->creation_ts),
         creation_time => $self->type('dateTime', $comment->creation_ts),
-        is_private    => $self->type('boolean', $comment->is_private),
-        is_markdown   => $self->type('boolean', $comment->is_markdown),
-        text          => $self->type('string', $comment->body_full),
+        is_private => $self->type('boolean', $comment->is_private),
+        text       => $self->type('string', $comment->body_full),
         attachment_id => $self->type('int', $attach_id),
-        count         => $self->type('int', $comment->count),
+        count      => $self->type('int', $comment->count),
     };
 
     # Don't load comment tags unless enabled
@@ -825,20 +822,10 @@ sub add_attachment {
 
         $attachment->update($timestamp);
         my $comment = $params->{comment} || '';
-
-        my $is_markdown = 0;
-        if (ref $params->{comment} eq 'HASH') {
-            $is_markdown = $params->{comment}->{is_markdown};
-            $comment     = $params->{comment}->{body};
-        }
-
-        ThrowUserError('markdown_disabled') if $is_markdown && !_is_markdown_enabled();
-
-        $attachment->bug->add_comment($comment,
-            { is_markdown => $is_markdown,
-              isprivate   => $attachment->isprivate,
-              type        => CMT_ATTACHMENT_CREATED,
-              extra_data  => $attachment->id });
+        $attachment->bug->add_comment($comment, 
+            { isprivate  => $attachment->isprivate,
+              type       => CMT_ATTACHMENT_CREATED,
+              extra_data => $attachment->id });
         push(@created, $attachment);
     }
     $_->bug->update($timestamp) foreach @created;
@@ -884,14 +871,6 @@ sub update_attachment {
 
     my $flags = delete $params->{flags};
     my $comment = delete $params->{comment};
-    my $is_markdown = 0;
-
-    if (ref $comment eq 'HASH') {
-        $is_markdown = $comment->{is_markdown};
-        $comment     = $comment->{body};
-    }
-
-    ThrowUserError('markdown_disabled') if $is_markdown && !_is_markdown_enabled();
 
     # Update the values
     foreach my $attachment (@attachments) {
@@ -911,10 +890,9 @@ sub update_attachment {
 
         if ($comment = trim($comment)) {
             $attachment->bug->add_comment($comment,
-                { is_markdown => $is_markdown,
-                  isprivate   => $attachment->isprivate,
-                  type        => CMT_ATTACHMENT_UPDATED,
-                  extra_data  => $attachment->id });
+                { isprivate  => $attachment->isprivate,
+                  type       => CMT_ATTACHMENT_UPDATED,
+                  extra_data => $attachment->id });
         }
 
         $changes = translate($changes, ATTACHMENT_MAPPED_RETURNS);
@@ -971,13 +949,9 @@ sub add_comment {
     if (defined $params->{private}) {
         $params->{is_private} = delete $params->{private};
     }
-
-    ThrowUserError('markdown_disabled') if $params->{is_markdown} && !_is_markdown_enabled();
-
     # Append comment
-    $bug->add_comment($comment, { isprivate   => $params->{is_private},
-                                  is_markdown => $params->{is_markdown},
-                                  work_time   => $params->{work_time} });
+    $bug->add_comment($comment, { isprivate => $params->{is_private},
+                                  work_time => $params->{work_time} });
     
     # Capture the call to bug->update (which creates the new comment) in 
     # a transaction so we're sure to get the correct comment_id.
@@ -1425,14 +1399,6 @@ sub _add_update_tokens {
     }
 }
 
-sub _is_markdown_enabled {
-    my $user = Bugzilla->user;
-
-    return Bugzilla->feature('markdown')
-            && $user->settings->{use_markdown}->{is_enabled}
-            && $user->setting('use_markdown') eq 'on';
-}
-
 1;
 
 __END__
@@ -2110,10 +2076,6 @@ may be deprecated and removed in a future release.
 C<boolean> True if this comment is private (only visible to a certain
 group called the "insidergroup"), False otherwise.
 
-=item is_markdown
-
-C<boolean> True if this comment needs Markdown processing, false otherwise.
-
 =back
 
 =item B<Errors>
@@ -3131,9 +3093,6 @@ don't want it to be assigned to the component owner.
 =item C<comment_is_private> (boolean) - If set to true, the description
 is private, otherwise it is assumed to be public.
 
-=item C<is_markdown> (boolean) - If set to true, the description
-has Markdown structures, otherwise it is a normal text.
-
 =item C<groups> (array) - An array of group names to put this
 bug into. You can see valid group names on the Permissions
 tab of the Preferences screen, or, if you are an administrator,
@@ -3289,8 +3248,6 @@ Bugzilla B<4.4>.
 
 =item REST API call added in Bugzilla B<5.0>.
 
-=item C<is_markdown> option added in Bugzilla B<5.0>.
-
 =back
 
 =back
@@ -3350,21 +3307,7 @@ C<text/plain> or C<image/png>.
 
 =item C<comment>
 
-C<string> or hash. A comment to add along with this attachment. If C<comment>
-is a hash, it has the following keys:
-
-=over
-
-=item C<body>
-
-C<string> The body of the comment.
-
-=item C<is_markdown>
-
-C<boolean> If set to true, the comment has Markdown structures; otherwise, it
-is an ordinary text.
-
-=back
+C<string> A comment to add along with this attachment.
 
 =item C<is_patch>
 
@@ -3442,10 +3385,6 @@ the type id value to update or add a flag.
 
 The flag type is inactive and cannot be used to create new flags.
 
-=item 140 (Markdown Disabled)
-
-You tried to set the C<is_markdown> flag of the comment to true but the Markdown feature is not enabled.
-
 =item 600 (Attachment Too Large)
 
 You tried to attach a file that was larger than Bugzilla will accept.
@@ -3481,8 +3420,6 @@ You set the "data" field to an empty string.
 
 =item REST API call added in Bugzilla B<5.0>.
 
-=item C<is_markdown> added in Bugzilla B<5.0>.
-
 =back
 
 =back
@@ -3529,21 +3466,7 @@ attachment.
 
 =item C<comment>
 
-C<string> or hash: An optional comment to add to the attachment's bug. If C<comment> is
-a hash, it has the following keys:
-
-=over
-
-=item C<body>
-
-C<string> The body of the comment to be added.
-
-=item C<is_markdown>
-
-C<boolean> If set to true, the comment has Markdown structures; otherwise it is a normal
-text.
-
-=back
+C<string> An optional comment to add to the attachment's bug.
 
 =item C<content_type>
 
@@ -3692,11 +3615,6 @@ the type id value to update or add a flag.
 
 The flag type is inactive and cannot be used to create new flags.
 
-=item 140 (Markdown Disabled)
-
-You tried to set the C<is_markdown> flag of the C<comment> to true but Markdown feature is
-not enabled.
-
 =item 601 (Invalid MIME Type)
 
 You specified a C<content_type> argument that was blank, not a valid
@@ -3757,9 +3675,6 @@ you did not set the C<comment> parameter.
 =item C<is_private> (boolean) - If set to true, the comment is private, 
 otherwise it is assumed to be public.
 
-=item C<is_markdown> (boolean) - If set to true, the comment has Markdown
-structures, otherwise it is a normal text.
-
 =item C<work_time> (double) - Adds this many hours to the "Hours Worked"
 on the bug. If you are not in the time tracking group, this value will
 be ignored.
@@ -3801,11 +3716,6 @@ You tried to add a private comment, but don't have the necessary rights.
 You tried to add a comment longer than the maximum allowed length
 (65,535 characters).
 
-=item 140 (Markdown Disabled)
-
-You tried to set the C<is_markdown> flag to true but the Markdown feature
-is not enabled.
-
 =back
 
 =item B<History>
@@ -3828,8 +3738,6 @@ code of 32000.
 
 =item REST API call added in Bugzilla B<5.0>.
 
-=item C<is_markdown> option added in Bugzilla B<5.0>.
-
 =back
 
 =back
diff --git a/Bugzilla/WebService/Constants.pm b/Bugzilla/WebService/Constants.pm
index db50611cb..d612ebc75 100644
--- a/Bugzilla/WebService/Constants.pm
+++ b/Bugzilla/WebService/Constants.pm
@@ -101,7 +101,6 @@ use constant WS_ERROR_CODE => {
     comment_id_invalid => 111,
     comment_too_long => 114,
     comment_invalid_isprivate => 117,
-    markdown_disabled => 140,
     # Comment tagging
     comment_tag_disabled => 125,
     comment_tag_invalid => 126,
diff --git a/docs/en/rst/using.rst b/docs/en/rst/using.rst
index eb887093b..da0d19450 100644
--- a/docs/en/rst/using.rst
+++ b/docs/en/rst/using.rst
@@ -404,7 +404,7 @@ You can use it to find a bug by its number or its alias, too.
 
 You'll find the Quicksearch box in Bugzilla's footer area.
 On Bugzilla's front page, there is an additional
-`quicksearcgh help <../../../page.cgi?id=quicksearch.html>`_
+`Help <../../page.cgi?id=quicksearch.html>`_
 link which details how to use it.
 
 .. _casesensitivity:
@@ -757,23 +757,6 @@ Don't use sigs in comments. Signing your name ("Bill") is acceptable,
 if you do it out of habit, but full mail/news-style
 four line ASCII art creations are not.
 
-.. _markdown:
-
-Markdown
---------
-
-Markdown lets you write your comments in a structured plain-text format and
-have your comments generated as HTML. For example, you may use Markdown for
-making a part of your comment look italic or bold in the generated HTML. Bugzilla
-supports most of the structures defined by `standard Markdown <http://daringfireball.net/projects/markdown/basics>`_.
-but does NOT support inline images and inline HTML. For a complete reference on
-supported Markdown structures, please see the `syntax help <../../../page.cgi?id=markdown.html>`_
-link next to the markdown checkbox for new comments.
-
-To use the Markdown feature, make sure that ``Enable Markdown support for comments`` is set to ``on``
-in your :ref:`userpreferences` and that you also check the ``Use Markdown for this comment`` option below
-the comment box when you want to submit a new comment.
-
 .. _comment-wrapping:
 
 Server-Side Comment Wrapping
diff --git a/js/field.js b/js/field.js
index c24603988..5589bc498 100644
--- a/js/field.js
+++ b/js/field.js
@@ -983,33 +983,17 @@ function initDirtyFieldTracking() {
  */
 
 var last_comment_text = '';
-var last_markdown_cb_value = null;
-var comment_textarea_width = null;
-var comment_textarea_height = null;
 
-function refresh_markdown_preview (bug_id) {
-    if (!YAHOO.util.Dom.hasClass('comment_preview_tab', 'active_comment_tab'))
-        return;
-    show_comment_preview(bug_id, 1);
-}
-
-function show_comment_preview(bug_id, refresh) {
+function show_comment_preview(bug_id) {
     var Dom = YAHOO.util.Dom;
     var comment = document.getElementById('comment');
     var preview = document.getElementById('comment_preview');
-    var markdown_cb = document.getElementById('use_markdown');
 
     if (!comment || !preview) return;
-    if (Dom.hasClass('comment_preview_tab', 'active_comment_tab') && !refresh)
-        return;
+    if (Dom.hasClass('comment_preview_tab', 'active_comment_tab')) return;
 
-    if (!comment_textarea_width) {
-        comment_textarea_width = (comment.clientWidth - 4) + 'px';
-        comment_textarea_height = comment.offsetHeight + 'px';
-    }
-
-    preview.style.width = comment_textarea_width;
-    preview.style.height = comment_textarea_height;
+    preview.style.width = (comment.clientWidth - 4) + 'px';
+    preview.style.height = comment.offsetHeight + 'px';
 
     var comment_tab = document.getElementById('comment_tab');
     Dom.addClass(comment, 'bz_default_hidden');
@@ -1023,7 +1007,7 @@ function show_comment_preview(bug_id, refresh) {
 
     Dom.addClass('comment_preview_error', 'bz_default_hidden');
 
-    if (last_comment_text == comment.value && last_markdown_cb_value == markdown_cb.checked)
+    if (last_comment_text == comment.value)
         return;
 
     Dom.addClass('comment_preview_text', 'bz_default_hidden');
@@ -1043,14 +1027,7 @@ function show_comment_preview(bug_id, refresh) {
                 document.getElementById('comment_preview_text').innerHTML = data.result.html;
                 Dom.addClass('comment_preview_loading', 'bz_default_hidden');
                 Dom.removeClass('comment_preview_text', 'bz_default_hidden');
-                if (markdown_cb.checked) {
-                    Dom.removeClass('comment_preview_text', 'comment_preview_pre');
-                }
-                else {
-                    Dom.addClass('comment_preview_text', 'comment_preview_pre');
-                }
                 last_comment_text = comment.value;
-                last_markdown_cb_value = markdown_cb.checked;
             }
         },
         failure: function(res) {
@@ -1066,8 +1043,7 @@ function show_comment_preview(bug_id, refresh) {
         params: {
             Bugzilla_api_token: BUGZILLA.api_token,
             id: bug_id,
-            text: comment.value,
-            markdown: (markdown_cb != null) && markdown_cb.checked ? 1 : 0
+            text: comment.value
         }
     })
     );
diff --git a/post_bug.cgi b/post_bug.cgi
index 9da8faec1..4680d6804 100755
--- a/post_bug.cgi
+++ b/post_bug.cgi
@@ -118,7 +118,6 @@ foreach my $field (qw(cc groups)) {
     $bug_params{$field} = [$cgi->param($field)];
 }
 $bug_params{'comment'} = $comment;
-$bug_params{'is_markdown'} = $cgi->param('use_markdown');
 
 my @multi_selects = grep {$_->type == FIELD_TYPE_MULTI_SELECT && $_->enter_bug}
                          Bugzilla->active_custom_fields;
diff --git a/process_bug.cgi b/process_bug.cgi
index b3d979960..fbd302974 100755
--- a/process_bug.cgi
+++ b/process_bug.cgi
@@ -233,13 +233,9 @@ if (should_set('keywords')) {
     $set_all_fields{keywords}->{$action} = $cgi->param('keywords');
 }
 if (should_set('comment')) {
-    my $is_markdown = ($user->use_markdown
-                       && $cgi->param('use_markdown') eq '1') ? 1 : 0;
-
     $set_all_fields{comment} = {
         body        => scalar $cgi->param('comment'),
         is_private  => scalar $cgi->param('comment_is_private'),
-        is_markdown => $is_markdown,
     };
 }
 if (should_set('see_also')) {
diff --git a/skins/standard/global.css b/skins/standard/global.css
index 60e06af73..74005319a 100644
--- a/skins/standard/global.css
+++ b/skins/standard/global.css
@@ -243,15 +243,6 @@
     textarea {
         font-family: monospace;
     }
-
-    blockquote {
-        border-left: 0.2em solid #CCC;
-        color: #65379C;
-        padding: 0;
-        margin-left: 0.5em;
-        margin-bottom: -1em;
-        white-space: pre;
-    }
 /* generic (end) */
 
 /* Links that control whether or not something is visible. */
@@ -319,7 +310,7 @@ div#docslinks {
 }
 
 /* tbody.file pre is for the Diff view of attachments. */
-pre.bz_comment_text, .uneditable_textarea, tbody.file pre {
+.bz_comment_text, .uneditable_textarea, tbody.file pre {
      font-family: monospace;
      white-space: pre-wrap;
 }
@@ -732,16 +723,12 @@ input.required, select.required, span.required_explanation {
     width: auto;
 }
 
-.comment_preview_pre {
-    white-space: pre;
-}
-
 #comment_preview_loading {
     font-style: italic;
 }
 
 #comment {
-    margin: 0;
+    margin: 0px 0px 1em 0px;
 }
 
 /*******************/
diff --git a/t/004template.t b/t/004template.t
index b0ca5a629..d38f9e16b 100644
--- a/t/004template.t
+++ b/t/004template.t
@@ -88,7 +88,6 @@ foreach my $include_path (@include_paths) {
             wrap_comment => sub { return $_ },
             none      => sub { return $_ } ,
             ics       => [ sub { return sub { return $_; } }, 1] ,
-            markdown => sub { return $_ } ,
         },
     }
     );
diff --git a/t/008filter.t b/t/008filter.t
index 204bbdc43..f0a26d13f 100644
--- a/t/008filter.t
+++ b/t/008filter.t
@@ -212,7 +212,7 @@ sub directive_ok {
     return 1 if $directive =~ /FILTER\ (html|csv|js|base64|css_class_quote|ics|
                                         quoteUrls|time|uri|xml|lower|html_light|
                                         obsolete|inactive|closed|unitconvert|
-                                        txt|html_linebreak|markdown|none)\b/x;
+                                        txt|html_linebreak|none)\b/x;
 
     return 0;
 }
diff --git a/template/en/default/bug/comment.html.tmpl b/template/en/default/bug/comment.html.tmpl
index 76054f92a..96cbb63ed 100644
--- a/template/en/default/bug/comment.html.tmpl
+++ b/template/en/default/bug/comment.html.tmpl
@@ -32,16 +32,6 @@
   <div id="comment_preview" class="bz_default_hidden bz_comment">
     <div id="comment_preview_loading" class="bz_default_hidden">Generating Preview...</div>
     <div id="comment_preview_error" class="bz_default_hidden"></div>
-    <div id="comment_preview_text" class="bz_comment_text"></div>
-  </div>
-[% END %]
-
-[% IF user.use_markdown %]
-  <div id="comment_markdown">
-    <input type="checkbox" name="use_markdown"
-           id="use_markdown" value="1" checked="checked"
-           onchange="refresh_markdown_preview([% bug.id FILTER none %])">
-    <label id="use_markdown_label" for="use_markdown">Use Markdown for this [% terms.comment %]</label>
-    (<a href="page.cgi?id=markdown.html" target="_blank" title="View Markdown Syntax Guide">help</a>)
+    <pre id="comment_preview_text" class="bz_comment_text"></pre>
   </div>
 [% END %]
diff --git a/template/en/default/bug/comments.html.tmpl b/template/en/default/bug/comments.html.tmpl
index 3895691d7..d040e651d 100644
--- a/template/en/default/bug/comments.html.tmpl
+++ b/template/en/default/bug/comments.html.tmpl
@@ -14,16 +14,13 @@
 <script type="text/javascript">
 <!--
   /* Adds the reply text to the 'comment' textarea */
-  function replyToComment(id, real_id, name, text) {
+  function replyToComment(id, real_id, name) {
       var prefix = "(In reply to " + name + " from comment #" + id + ")\n";
       var replytext = "";
       [% IF user.settings.quote_replies.value == 'quoted_reply' %]
         /* pre id="comment_name_N" */
-
-        if (text == null) {
-            var text_elem = document.getElementById('comment_text_'+id);
-            text = getText(text_elem);
-        }
+        var text_elem = document.getElementById('comment_text_'+id);
+        var text = getText(text_elem);
         replytext = prefix + wrapReplyText(text);
       [% ELSIF user.settings.quote_replies.value == 'simple_reply' %]
         replytext = prefix;
@@ -44,39 +41,6 @@
 
       textarea.focus();
   } 
-
-  function replyToMarkdownComment(id, real_id, name) {
-      var textarea = document.getElementById('comment');
-      var comment = textarea.value;
-      textarea.value += "Fetching comment...";
-      YAHOO.util.Connect.setDefaultPostHeader('application/json', true);
-      YAHOO.util.Connect.asyncRequest('POST', 'jsonrpc.cgi',
-      {
-          success: function(res) {
-              var data = YAHOO.lang.JSON.parse(res.responseText);
-              if (!data.error) {
-                  textarea.value = comment;
-                  var text = data.result.comments[real_id].text;
-                  replyToComment(id, real_id, name, text);
-              } else {
-                  replyToComment(id, real_id, name, null);
-              }
-          },
-          failure: function(res) {
-              /* On failure, quote the comment as plain-text */
-              replyToComment(id, real_id, name, null);
-          }
-      },
-      YAHOO.lang.JSON.stringify({
-          version: "1.1",
-          method: "Bug.comments",
-          params: {
-              Bugzilla_api_token: BUGZILLA.api_token,
-              comment_ids: [real_id],
-          }
-      })
-      );
-  }
 //-->
 </script>
 
@@ -162,13 +126,7 @@
               [% END %]
               [<a class="bz_reply_link" href="#add_comment"
                 [% IF user.settings.quote_replies.value != 'off' %]
-                  onclick="
-                  [% IF feature_enabled('jsonrpc') && comment.is_markdown %]
-                    replyToMarkdownComment('[% comment.count %]', '[% comment.id %]', '[% comment.author.name || comment.author.nick FILTER html FILTER js %]'); return false;"
-                  [% ELSE %]
-                    replyToComment('[% comment.count %]', '[% comment.id %]', '[% comment.author.name || comment.author.nick FILTER html FILTER js %]', null); return false;"
-
-                  [% END %]
+                  onclick="replyToComment('[% comment.count %]', '[% comment.id %]', '[% comment.author.name || comment.author.nick FILTER html FILTER js %]'); return false;"
                 [% END %]
               >reply</a>]
             [% END %]
@@ -267,12 +225,12 @@
 [%# Don't indent the <pre> block, since then the spaces are displayed in the
   # generated HTML
   #%]
-<[% user.use_markdown(comment) ? "div" : "pre" %] class="bz_comment_text[% " collapsed" IF comment.collapsed %]"
+<pre class="bz_comment_text[% " collapsed" IF comment.collapsed %]"
   [% IF mode == "edit" || comment.collapsed %]
     id="comment_text_[% comment.count FILTER none %]"
   [% END %]>
-  [%- comment_text FILTER markdown(bug, comment) -%]
-</[% user.use_markdown(comment) ? "div" : "pre" %]>
+  [%- comment_text FILTER quoteUrls(bug, comment) -%]
+</pre>
     [% Hook.process('a_comment-end', 'bug/comments.html.tmpl') %]
     </div>
 [% END %]
diff --git a/template/en/default/bug/process/midair.html.tmpl b/template/en/default/bug/process/midair.html.tmpl
index f89590df2..17025fee7 100644
--- a/template/en/default/bug/process/midair.html.tmpl
+++ b/template/en/default/bug/process/midair.html.tmpl
@@ -76,7 +76,6 @@ You have the following choices:
         <input type="hidden" name="id" value="[% cgi.param("id") FILTER html %]">
         <input type="hidden" name="delta_ts" value="[% bug.delta_ts FILTER html %]">
         <input type="hidden" name="comment" value="[% cgi.param("comment") FILTER html %]">
-        <input type="hidden" name="use_markdown" value="[% cgi.param("use_markdown") FILTER html %]">
         <input type="hidden" name="comment_is_private"
                value="[% cgi.param("comment_is_private") FILTER html %]">
         <input type="hidden" name="token" value="[% cgi.param("token") FILTER html %]">
diff --git a/template/en/default/email/bugmail.html.tmpl b/template/en/default/email/bugmail.html.tmpl
index b0f4efb45..9473a4459 100644
--- a/template/en/default/email/bugmail.html.tmpl
+++ b/template/en/default/email/bugmail.html.tmpl
@@ -25,7 +25,7 @@
               on [% "$terms.bug $bug.id" FILTER bug_link(bug, { full_url => 1, user => to_user }) FILTER none %]
               from [% INCLUDE global/user.html.tmpl user = to_user, who = comment.author %]</b>
           [% END %]
-        <pre>[% comment.body_full({ wrap => 1 }) FILTER markdown(bug, comment, to_user) %]</pre>
+        <pre>[% comment.body_full({ wrap => 1 }) FILTER quoteUrls(bug, comment, to_user) %]</pre>
         </div>
       [% END %]
       </p>
diff --git a/template/en/default/filterexceptions.pl b/template/en/default/filterexceptions.pl
index f5f1bd783..6adbbcb95 100644
--- a/template/en/default/filterexceptions.pl
+++ b/template/en/default/filterexceptions.pl
@@ -20,7 +20,7 @@
 #                                   [% foo.push() %]
 # TT loop variables               - [% loop.count %]
 # Already-filtered stuff          - [% wibble FILTER html %]
-#   where the filter is one of html|csv|js|quoteUrls|time|uri|xml|markdown|none
+#   where the filter is one of html|csv|js|quoteUrls|time|uri|xml|none
 
 %::safe = (
 
diff --git a/template/en/default/global/setting-descs.none.tmpl b/template/en/default/global/setting-descs.none.tmpl
index ac99094c5..6e3358782 100644
--- a/template/en/default/global/setting-descs.none.tmpl
+++ b/template/en/default/global/setting-descs.none.tmpl
@@ -44,8 +44,7 @@
    "requestee_cc"                     => "Automatically add me to the CC list of $terms.bugs I am requested to review",
    "bugmail_new_prefix"               => "Add 'New:' to subject line of email sent when a new $terms.bug is filed",
    "possible_duplicates"              => "Display possible duplicates when reporting a new $terms.bug", 
-   "use_markdown"                     => "Enable Markdown support for $terms.comments"
-  }
+                   } 
 %]
 
 [% Hook.process('settings') %]
diff --git a/template/en/default/global/user-error.html.tmpl b/template/en/default/global/user-error.html.tmpl
index e9bdb63c4..a0ae25c08 100644
--- a/template/en/default/global/user-error.html.tmpl
+++ b/template/en/default/global/user-error.html.tmpl
@@ -1181,9 +1181,6 @@
     [%# Used for non-web-based LOGIN_REQUIRED situations. %]
     You must log in before using this part of [% terms.Bugzilla %].
 
-  [% ELSIF error == "markdown_disabled" %]
-    Markdown feature is not enabled.
-
   [% ELSIF error == "migrate_config_created" %]
     The file <kbd>[% file FILTER html %]</kbd> contains configuration
     variables that must be set before continuing with the migration.
diff --git a/template/en/default/pages/linked.html.tmpl b/template/en/default/pages/linked.html.tmpl
index ab74470c2..3fcf87952 100644
--- a/template/en/default/pages/linked.html.tmpl
+++ b/template/en/default/pages/linked.html.tmpl
@@ -18,7 +18,7 @@
 
 <p>
 <pre class="bz_comment_text">
-[%- cgi.param("text") FILTER markdown FILTER html -%]
+[%- cgi.param("text") FILTER quoteUrls FILTER html -%]
 </pre>
 </p>
 
@@ -33,7 +33,7 @@
 
 <p>
 <pre class="bz_comment_text">
-[%- cgi.param("text") FILTER markdown -%]
+[%- cgi.param("text") FILTER quoteUrls -%]
 </pre>
 </p>
 
diff --git a/template/en/default/pages/markdown.html.tmpl b/template/en/default/pages/markdown.html.tmpl
deleted file mode 100644
index 8b43f5f17..000000000
--- a/template/en/default/pages/markdown.html.tmpl
+++ /dev/null
@@ -1,265 +0,0 @@
-[%# this source code form is subject to the terms of the mozilla public
-  # license, v. 2.0. if a copy of the mpl was not distributed with this
-  # file, you can obtain one at http://mozilla.org/mpl/2.0/.
-  #
-  # this source code form is "incompatible with secondary licenses", as
-  # defined by the mozilla public license, v. 2.0.
-  #%]
-
-[% INCLUDE global/header.html.tmpl
-  title = "Markdown Syntax Guide"
-  bodyclasses = ['narrow_page']
- %]
-
-<h2>What is Markdown?</h2>
-
-  Markdown is a simple text formatting language that enables you to write your
-  [%+ terms.comments %] in plain-text and have them generated as HTML. Markdown
-  in [%+ terms.Bugzilla %] supports the following structures:
-
-  <ul>
-    <li><a href="#headers">Headers</a></li>
-    <li><a href="#blockquotes">Blockquotes</a></li>
-    <li><a href="#emphasis">Emphasis</a></li>
-    <li><a href="#lists">Lists</a></li>
-    <li><a href="#code">Code</a></li>
-    <li><a href="#strikethroughs">Strikethroughs</a></li>
-    <li><a href="#links">Links</a></li>
-  </ul>
-
-<h2 id="headers">Headers</h2>
-
-  You have two options for making headers. First, you may use any number of
-  equal signs (for first-level header) or dashes (for second-level headers).
-
-  <p>
-    <pre>
-      <code>
-        This is an H1 header
-        ====================
-
-        This is an H2 header
-        --------------------
-      </code>
-    </pre>
-  </p>
-
-  Second, you can use hash signs at the beginning of the line to specify the
-  level of the header from 1 to 6.
-
-  <p>
-    <pre>
-      <code>
-        # This is the largest header (H1 level)
-        ### This is a small header (H3 level)
-        ###### This is the smallest header (H6 level)
-     </code>
-   </pre>
-  </p>
-
-<h2 id="blockquotes">Blockquotes</h2>
-
-  Use a closing angle bracket (<code>&gt;</code>) at the beginning of the line
-  to indicate a line as quoted.
-
-  <p>
-    <pre>
-      <code>
-        &gt; Some text to be quoted.
-      </code>
-    </pre>
-  </p>
-
-<h2 id="emphasis">Emphasis</h2>
-
-  Single underscores or asterisks will make the text italic. Double underscores
-  or asterisks will make the text bold.
-
-  <p>
-    <pre>
-      <code>
-        _This text will become italic_
-        *This text also will become italic*
-
-        __But this one will be bold__
-        **And this one as well**
-      </code>
-    </pre>
-  </p>
-
-  Turns into
-
-  <p>
-    <pre>
-      <em>This text will become italic</em>
-      <em>This text also will become italic</em>
-      <br>
-      <strong>But this one will be bold</strong>
-      <strong>And this one as well</strong>
-    </pre>
-  </p>
-
-  Use different signs to combine them nestedly in order to avoid ambiguity:
-
-  <p>
-    <pre>
-      <code>
-        _This [% terms.bug %] **must** be resolved ASAP._
-      </code>
-    </pre>
-  </p>
-
-  <strong>Note:</strong> [% terms.Bugzilla %] will skip emphasizing words that
-  have the form of <code>multiple_underscore_in_a_word</code>. This measure is
-  taken to not emphasize words that are possible programming variables. If your
-  word has this form and you still want it to become emphasized/bold, you must
-  use single/double asterisks (<code>*</code>) instead of underscores
-  (<code>_</code>).
-
-<h2 id="lists">Lists</h2>
-
-  Markdown supports both unordered and ordered lists.
-
-  <h3>Unordered Lists</h3>
-
-    Use asterisks (<code>*</code>), pluses (<code>+</code>) or hyphens
-    (<code>-</code>) to mark the items of an unordered list.
-
-    <p>
-      <pre>
-        <code>
-          + First item
-          + Second item
-          + Third item
-        </code>
-      </pre>
-    </p>
-
-  <h3>Ordered Lists</h3>
-
-    Use a number followed by a period to denote an item of an ordered list.
-
-    <p>
-      <pre>
-        <code>
-          1. Item one
-          4. Item two
-          3. Item three
-        </code>
-      </pre>
-    </p>
-
-    <strong>Note:</strong> Your numbers have no effect on the rendered item
-    numbers and the rendered numbers are automatically generated. Your numbers
-    are only used to specify the items of an ordered list.<br>
-
-    <p>
-      A list item can have nested lists recursively:
-    </p>
-
-    <p>
-      <pre>
-        <code>
-          1. Item one
-          4. Item two
-          3. Item three
-            * First sub-item
-            * Second sub-item
-          5. Item four
-        </code>
-      </pre>
-    </p>
-
-<h2 id="code">Code</h2>
-
-  To make a part of your text to get generated as a piece of code, use one or
-  more backticks (<code>`</code>) and close that
-  part with the same number of backticks.
-
-  <p>
-    <pre>
-      <code>Please see the manual for `printf` function.</code>
-    </pre>
-  </p>
-
-  If you want to make some lines of code, you need to use 3 or more backticks at
-  the beginning of a line followed by your code lines and concluded by 3 or more
-  backticks.
-
-  <p>
-    <pre>
-      <code>
-        See my function:
-        ```
-        int sum(int x, int y) {
-          return x + y;
-        }
-        ```
-      </code>
-    </pre>
-  </p>
-
-  You can also use a tab or [% constants.MARKDOWN_TAB_WIDTH FILTER html %] or
-  more spaces at the beginning of each line of your code to make the whole block
-  look as a code block. Please take care that you might make your lines as code
-  blocks by inadvertently indenting them.
-
-<h2 id="strikethroughs">Strikethroughs</h2>
-
-  Surround your text between a pair of two tildes to have your text crossed out.
-
-  <p>
-    <pre>
-      <code>
-        Module ~~Foo~~ is deprecated.
-      </code>
-    </pre>
-  </p>
-
-<h2 id="links">Links</h2>
-
-  Literal URLs and Email addresses get linkified automatically. Besides that,
-  you can define links with link texts and titles. You may define your links
-  either as inline or as a reference. To define a link as inline, put your link
-  text in square bracket immediately followed by a pair of parentheses which
-  containts the URL that you want your link to point to and an <em>optional</em>
-  link title surrounded by quotes.
-
-  <p>
-    <pre>
-      <code>
-        This is [Bugzilla](http://www.bugzilla.org "View Bugzilla Homepage")
-        [% terms.bug %] tracking system.</code>
-        This [example link](http://www.example.com) does not have title.
-      </code>
-    </pre>
-  </p>
-
-  To define your links in a reference style, define your links any where in
-  your [% terms.comment %] with the following format:
-
-  <p>
-    <pre>
-      <code>
-        [bz]: http://www.bugzilla.org "Bugzilla Homepage"
-        [mz]: http://www.mozilla.org (Mozilla Homepage)
-      </code>
-    </pre>
-  </p>
-
-  That is, define a unique ID for each link in square brackets with their
-  corresponding URL and optional title in quotes or parentheses. Then, point to
-  those links simply by writing your link text in square brackets followed by
-  the ID in another pair of square brackets.
-
-  <p>
-    <pre>
-      <code>
-        [Bugzilla][bz] is open-sourced server software designed to help groups
-        manage software development. [Mozilla][mz] uses [Bugzilla][bz] to track
-        issues with Firefox and other projects.
-      </code>
-    </pre>
-  </p>
-
-[% PROCESS global/footer.html.tmpl %]
diff --git a/template/en/default/setup/strings.txt.pl b/template/en/default/setup/strings.txt.pl
index 6de588e6d..7dc8e8bf1 100644
--- a/template/en/default/setup/strings.txt.pl
+++ b/template/en/default/setup/strings.txt.pl
@@ -101,7 +101,6 @@ END
     feature_xmlrpc            => 'XML-RPC Interface',
     feature_detect_charset    => 'Automatic charset detection for text attachments',
     feature_typesniffer       => 'Sniff MIME type of attachments',
-    feature_markdown          => 'Markdown syntax support for comments',
 
     file_remove => 'Removing ##name##...',
     file_rename => 'Renaming ##from## to ##to##...',