ensure return values are used

5 files changed, 138 insertions, 61 deletions

diff --git a/perl_checker.src/lexer.mll b/perl_checker.src/lexer.mll
index a787ac2..5a9fd4b 100644
--- a/perl_checker.src/lexer.mll
+++ b/perl_checker.src/lexer.mll
@@ -72,7 +72,7 @@ let rec raw_token_to_pos_and_token spaces = function
   | RAW_STRING(s, pos) -> pos, Parser.RAW_STRING(new_any M_string s spaces pos)
   | RAW_HERE_DOC(r, pos) -> pos, Parser.RAW_HERE_DOC(new_any M_string !r spaces pos)
   | STRING(l, pos) -> pos, Parser.STRING(new_any M_string (raw_interpolated_string_to_tokens l) spaces pos)
-  | COMMAND_STRING(l, pos) -> pos, Parser.COMMAND_STRING(new_any (M_mixed (M_string, M_array)) (raw_interpolated_string_to_tokens l) spaces pos)
+  | COMMAND_STRING(l, pos) -> pos, Parser.COMMAND_STRING(new_any (M_mixed [M_string; M_array]) (raw_interpolated_string_to_tokens l) spaces pos)
   | QR_PATTERN(s, opts, pos) -> pos, Parser.QR_PATTERN(new_any M_special (raw_interpolated_string_to_tokens s, opts) spaces pos)
   | PATTERN(s, opts, pos) -> pos, Parser.PATTERN(new_any M_special (raw_interpolated_string_to_tokens s, opts) spaces pos)
   | PATTERN_SUBST(from, to_, opts, pos) -> pos, Parser.PATTERN_SUBST(new_any M_special (raw_interpolated_string_to_tokens from, raw_interpolated_string_to_tokens to_, opts) spaces pos)
@@ -80,10 +80,10 @@ let rec raw_token_to_pos_and_token spaces = function
   | BAREWORD(s, pos) -> pos, Parser.BAREWORD(new_any M_special s spaces pos)
   | BAREWORD_PAREN(s, pos) -> pos, Parser.BAREWORD_PAREN(new_any M_special s spaces pos)
   | REVISION(s, pos) -> pos, Parser.REVISION(new_any M_revision s spaces pos)
-  | PERL_CHECKER_COMMENT(s, pos) -> pos, Parser.PERL_CHECKER_COMMENT(new_any M_special s spaces pos)
+  | PERL_CHECKER_COMMENT(s, pos) -> pos, Parser.PERL_CHECKER_COMMENT(new_any M_none s spaces pos)
   | PO_COMMENT(s, pos) -> pos, Parser.PO_COMMENT(new_any M_special s spaces pos)
   | POD(s, pos) -> pos, Parser.POD(new_any M_special s spaces pos)
-  | LABEL(s, pos) -> pos, Parser.LABEL(new_any M_special s spaces pos)
+  | LABEL(s, pos) -> pos, Parser.LABEL(new_any M_none s spaces pos)
   | PRINT(s, pos) -> pos, Parser.PRINT(new_any M_special s spaces pos)
   | PRINT_TO_STAR(s, pos) -> pos, Parser.PRINT_TO_STAR(new_any M_special s spaces pos)
   | PRINT_TO_SCALAR(s, pos) -> pos, Parser.PRINT_TO_SCALAR(new_any M_special s spaces pos)
@@ -137,7 +137,7 @@ let rec raw_token_to_pos_and_token spaces = function
   | AMPERSAND        (pos) -> pos, Parser.AMPERSAND        (new_any M_special () spaces pos)
   | STAR             (pos) -> pos, Parser.STAR             (new_any M_special () spaces pos)
   | ARRAYLEN         (pos) -> pos, Parser.ARRAYLEN         (new_any M_special () spaces pos)
-  | SEMI_COLON       (pos) -> pos, Parser.SEMI_COLON       (new_any M_special () spaces pos)
+  | SEMI_COLON       (pos) -> pos, Parser.SEMI_COLON       (new_any M_none    () spaces pos)
   | PKG_SCOPE        (pos) -> pos, Parser.PKG_SCOPE        (new_any M_special () spaces pos)
   | PAREN            (pos) -> pos, Parser.PAREN            (new_any M_special () spaces pos)
   | PAREN_END        (pos) -> pos, Parser.PAREN_END        (new_any M_special () spaces pos)
@@ -450,6 +450,7 @@ rule token = parse
 | "length" 
 | "keys" 
 | "exists" 
+| "eval"
 | "ref"      { ONE_SCALAR_PARA(lexeme lexbuf, pos lexbuf) }
 
 | "split"
diff --git a/perl_checker.src/parser.mly b/perl_checker.src/parser.mly
index ed2095d..2a45414 100644
--- a/perl_checker.src/parser.mly
+++ b/perl_checker.src/parser.mly
@@ -104,7 +104,7 @@ prog: lines EOF {$1.any}
 lines: /* A collection of "lines" in the program */
 | { default_esp [] }
 | sideff { new_1esp [$1.any] $1 }
-| line lines { new_esp $2.mcontext ($1.any @ $2.any) $1 $2 }
+| line lines { if $2.any <> [] then mcontext_check_none $1; new_esp $2.mcontext ($1.any @ $2.any) $1 $2 }
 
 line:
 | decl { new_1esp [$1.any] $1 }
@@ -114,7 +114,8 @@ line:
 | PERL_CHECKER_COMMENT {sp_p($1); new_1esp [Perl_checker_comment($1.any, get_pos $1)] $1 }
 | semi_colon {new_1esp [Semi_colon] $1 }
 | sideff semi_colon {new_1esp [$1.any ; Semi_colon] $1 }
-| BRACKET lines BRACKET_END {check_block_sub $2 $3; new_esp $2.mcontext [Block $2.any] $1 $3}
+| BRACKET lines BRACKET_END            {check_block_sub $2 $3; new_esp $2.mcontext [Block $2.any] $1 $3}
+| BRACKET lines BRACKET_END semi_colon {check_block_sub $2 $3; new_esp $2.mcontext [Block $2.any] $1 $4}
 
 if_then_else: /* Real conditional expressions */
 | IF     PAREN expr PAREN_END BRACKET lines BRACKET_END elsif else_ {sp_p($1); sp_n($2); sp_0($3); sp_0_or_cr($4); sp_p($5); mcontext_check M_scalar $3; check_block_sub $6 $7; to_Call_op (if $9.any = [] then M_none else mcontext_lmerge ($6.mcontext :: mcontext_lmaybe $8 @ [$9.mcontext])) "if"     (prio_lo P_loose $3 :: Block $6.any :: $8.any @ $9.any) $1 $9}
@@ -153,8 +154,8 @@ sideff: /* An expression which may have a side-effect */
 | expr  FOR    expr {sp_p($2); sp_p($3); mcontext_check M_list $3; check_foreach($2); to_Call_op M_none "for infix"   [ prio_lo P_loose $1 ; prio_lo P_loose $3 ] $1 $3}
 
 decl:
-| FORMAT BAREWORD ASSIGN {new_esp M_special Too_complex $1 $3}
-| FORMAT ASSIGN {new_esp M_special Too_complex $1 $2}
+| FORMAT BAREWORD ASSIGN {new_esp M_none Too_complex $1 $3}
+| FORMAT ASSIGN {new_esp M_none Too_complex $1 $2}
 | func_decl semi_colon {if snd $1.any = None then die_rule "there is no need to pre-declare in Perl!" else (warn_rule "please don't use prototype pre-declaration" ; new_esp M_special Too_complex $1 $2) }
 | func_decl BRACKET BRACKET_END {sp_n($2); sp_0_or_cr($3); let name, proto = $1.any in new_esp M_none (sub_declaration (name, proto) []) $1 $3}
 | func_decl BRACKET lines BRACKET_END {sp_n($2); check_block_sub $3 $4; new_esp M_none (sub_declaration $1.any $3.any) $1 $4}
@@ -211,25 +212,25 @@ term:
 | term BIT_AND    term {sp_same $2 $3; sp_p $2; let pri = P_bit       in to_Call_op_ (mcontext_symops M_int    $1 $3) pri "&"    [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term BIT_OR     term {sp_same $2 $3;          let pri = P_bit       in to_Call_op_ (mcontext_symops M_int    $1 $3) pri "|"    [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term BIT_XOR    term {sp_same $2 $3; sp_p $2; let pri = P_bit       in to_Call_op_ (mcontext_symops M_int    $1 $3) pri "^"    [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
-| term AND_TIGHT  term {sp_same $2 $3; sp_p $2; let pri = P_tight_and in to_Call_op_ (mcontext_symops M_scalar $1 $3) pri "&&"   [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
+| term AND_TIGHT  term {sp_same $2 $3; sp_p $2; let pri = P_tight_and in to_Call_op_ (mcontext_rightops M_scalar $1 $3) pri "&&" [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term OR_TIGHT   term {sp_same $2 $3; sp_p $2; let pri = P_tight_or  in to_Call_op_ (mcontext_symops M_scalar $1 $3) pri "||"   [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term MULT       term {sp_same $2 $3;          let pri = P_mul       in to_Call_op_ (mcontext_symops M_float  $1 $3) pri $2.any [prio_lo_concat $1; prio_lo_after pri $3] $1 $3}
 | term MULT_L_STR term {sp_same $2 $3; mcontext_check M_int $3; let pri = P_mul in to_Call_op_ (if mcontext_lower $1.mcontext M_string then M_string else M_list) pri "x" [prio_lo_concat $1; prio_lo_after pri $3] $1 $3}
 | term PLUS       term {sp_same $2 $3;          let pri = P_add       in to_Call_op_ (mcontext_symops M_float  $1 $3) pri $2.any [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term CONCAT     term {sp_same $2 $3;          let pri = P_add       in to_Call_op_ (mcontext_symops M_string $1 $3) pri "."    [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
-| term ASSIGN     term {sp_same $2 $3; mcontext_check_non_none $3 ; let pri = P_assign in to_Call_op_ $3.mcontext     pri $2.any [$1.any.expr   ; prio_lo_after pri $3] $1 $3}
+| term ASSIGN     term {sp_same $2 $3;          let pri = P_assign    in to_Call_op_ (mcontext_op_assign $1 $3)       pri $2.any [$1.any.expr   ; prio_lo_after pri $3] $1 $3}
 | term DOTDOT     term {sp_same $2 $3;          let pri = P_paren_wanted P_expr  in to_Call_op_ (mcontext_symops M_scalar $1 $3) pri $2.any [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term BIT_SHIFT  term {sp_same $2 $3;          let pri = P_paren_wanted P_tight in to_Call_op_ (mcontext_symops M_int    $1 $3) pri $2.any [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 | term XOR        term {sp_same $2 $3; sp_p $2; let pri = P_paren_wanted P_expr  in to_Call_op_ (mcontext_symops M_scalar $1 $3) pri "xor"  [prio_lo pri $1; prio_lo_after pri $3] $1 $3}
 
-| term ASSIGN     BRACKET expr BRACKET_END {sp_p($2); sp_p($3); sp_p($4); sp_p($5); to_Call_op_ (M_ref M_hash) P_assign $2.any [prio_lo P_assign $1; Ref(I_hash, $4.any.expr)] $1 $5}
+| term ASSIGN     BRACKET expr BRACKET_END {sp_p($2); sp_p($3); sp_p($4); sp_p($5); to_Call_op_ (M_mixed [M_ref M_hash; M_none]) P_assign $2.any [prio_lo P_assign $1; Ref(I_hash, $4.any.expr)] $1 $5}
 | term AND_TIGHT  BRACKET expr BRACKET_END {sp_p($2); sp_p($3); sp_p($4); sp_p($5); to_Call_op_ M_scalar P_tight_and "&&"   [prio_lo P_assign $1; Ref(I_hash, $4.any.expr)] $1 $5}
 | term OR_TIGHT   BRACKET expr BRACKET_END {sp_p($2); sp_p($3); sp_p($4); sp_p($5); to_Call_op_ M_scalar P_tight_or  "||"   [prio_lo P_assign $1; Ref(I_hash, $4.any.expr)] $1 $5}
 
 
 | term PATTERN_MATCH     PATTERN   {sp_n($2); sp_p($3); check_unneeded_var_dollar_   ($1); let pattern = from_PATTERN $3 in check_simple_pattern pattern ; to_Call_op_ M_array P_expr "m//"  ($1.any.expr :: pattern) $1 $3}
 | term PATTERN_MATCH_NOT PATTERN   {sp_n($2); sp_p($3); check_unneeded_var_dollar_not($1); let pattern = from_PATTERN $3 in check_simple_pattern pattern ; to_Call_op_ M_int   P_expr "!m//" ($1.any.expr :: pattern) $1 $3}
-| term PATTERN_MATCH PATTERN_SUBST {sp_n($2); sp_p($3); check_unneeded_var_dollar_s  ($1); to_Call_op_ M_int P_expr "s///" ($1.any.expr :: from_PATTERN_SUBST $3) $1 $3}
+| term PATTERN_MATCH PATTERN_SUBST {sp_n($2); sp_p($3); check_unneeded_var_dollar_s  ($1); to_Call_op_ (M_mixed[M_none; M_int]) P_expr "s///" ($1.any.expr :: from_PATTERN_SUBST $3) $1 $3}
 | term PATTERN_MATCH_NOT PATTERN_SUBST {die_with_rawpos $2.pos "use =~ instead of !~ and negate the return value"}
 
 | term PATTERN_MATCH     QR_PATTERN {sp_n($2); sp_p($3); to_Call_op_ M_array P_expr "m//"  ($1.any.expr :: from_PATTERN $3) $1 $3}
@@ -262,10 +263,10 @@ term:
 }
 | TIGHT_NOT term {check_negatable_expr $2; to_Call_op_ (mcontext_unop M_scalar $2) P_tight "not" [$2.any.expr] $1 $2}
 | BIT_NEG term {to_Call_op_ (mcontext_unop M_int $2) P_expr "~" [$2.any.expr] $1 $2}
-| INCR term    {sp_0($2); to_Call_op_ (mcontext_unop M_int $2) P_tight "++" [$2.any.expr] $1 $2}
-| DECR term    {sp_0($2); to_Call_op_ (mcontext_unop M_int $2) P_tight "--" [$2.any.expr] $1 $2}
-| term INCR    {sp_0($2); to_Call_op_ (mcontext_unop M_int $1) P_tight "++ post" [$1.any.expr] $1 $2}
-| term DECR    {sp_0($2); to_Call_op_ (mcontext_unop M_int $1) P_tight "-- post" [$1.any.expr] $1 $2}
+| INCR term    {sp_0($2); mcontext_check M_int $2; to_Call_op_ (M_mixed [M_int ; M_none]) P_tight "++" [$2.any.expr] $1 $2}
+| DECR term    {sp_0($2); mcontext_check M_int $2; to_Call_op_ (M_mixed [M_int ; M_none]) P_tight "--" [$2.any.expr] $1 $2}
+| term INCR    {sp_0($2); mcontext_check M_int $1; to_Call_op_ (M_mixed [M_int ; M_none]) P_tight "++ post" [$1.any.expr] $1 $2}
+| term DECR    {sp_0($2); mcontext_check M_int $1; to_Call_op_ (M_mixed [M_int ; M_none]) P_tight "-- post" [$1.any.expr] $1 $2}
 | NOT argexpr  {warn_rule "don't use \"not\", use \"!\" instead"; to_Call_op_ (mcontext_unop M_scalar $2) P_and "not" ($2.any.expr) $1 $2}
 
 /* Constructors for anonymous data */
@@ -285,7 +286,7 @@ term:
 | termdo {new_1pesp P_tok $1.any $1}
 | REF term {new_pesp (M_ref $2.mcontext) P_expr (Ref(I_scalar, remove_call_with_same_para_special $2.any.expr)) $1 $2} /* \$x, \@y, \%z */
 | my_our %prec UNIOP {new_1pesp P_expr $1.any $1}
-| LOCAL term    %prec UNIOP {sp_n($2); new_pesp $2.mcontext P_expr (to_Local $2) $1 $2}
+| LOCAL term    %prec UNIOP {sp_n($2); new_pesp M_none P_expr (to_Local $2) $1 $2}
 
 | parenthesized {new_1pesp $1.any.priority (List $1.any.expr) $1} /* (1, 2) */
 | parenthesized arrayref {sp_0($2); let is_slice = not (is_only_one_in_List $2.any) in new_pesp (if is_slice then M_list else M_scalar) P_tok (to_Deref_with(I_array, (if is_slice then I_array else I_scalar), List $1.any.expr, List $2.any)) $1 $2} /* list indexing or slicing */
@@ -311,14 +312,17 @@ term:
 | ONE_SCALAR_PARA restricted_subscripted   {call_one_scalar_para $1 [$2.any] $1 $2}
 | ONE_SCALAR_PARA parenthesized            {call_one_scalar_para $1 $2.any.expr $1 $2}
 | ONE_SCALAR_PARA word_paren parenthesized {call_one_scalar_para $1 [call(Deref(I_func, $2.any), $3.any.expr)] $1 $3}
+| ONE_SCALAR_PARA BRACKET lines BRACKET_END {sp_n($2); check_block_sub $3 $4; new_pesp M_unknown P_tok (call(Deref(I_func, Ident(None, $1.any, raw_pos2pos $1.pos)), [anonymous_sub None $3])) $1 $4} /* eval { foo } */
+| ONE_SCALAR_PARA diamond {call_one_scalar_para $1 [$2.any] $1 $2}
 | ONE_SCALAR_PARA {call_one_scalar_para $1 [] $1 $1}
 | ONE_SCALAR_PARA word argexpr {check_parenthesized_first_argexpr_with_Ident  $2.any $3; call_one_scalar_para $1 [call(Deref(I_func, $2.any), $3.any.expr)] $1 $3} /* ref foo $a, $b */
 | ONE_SCALAR_PARA hash PKG_SCOPE {sp_0($3); call_one_scalar_para $1 [ Call(Too_complex, [$2.any]) ] $1 $3} /* keys %main:: */
 
 | func parenthesized {sp_0($2); new_pesp M_unknown P_tok (call_func true ($1.any, $2.any.expr)) $1 $2} /* &foo(@args) */
 | word argexpr {check_parenthesized_first_argexpr_with_Ident  $1.any $2; new_pesp M_unknown P_call_no_paren (call(Deref(I_func, $1.any), $2.any.expr)) $1 $2} /* foo $a, $b */
+| word BRACKET lines BRACKET_END COMMA argexpr %prec LSTOP {sp_n($2); new_pesp M_unknown P_call_no_paren (call(Deref(I_func, $1.any), Ref(I_hash, List $3.any) :: $6.any.expr)) $1 $6} /* bless { foo }, $bar */
 | word_paren parenthesized {sp_0($2); new_pesp M_unknown P_tok (call(Deref(I_func, $1.any), $2.any.expr)) $1 $2} /* foo(@args) */
-| word BRACKET lines BRACKET_END listexpr %prec LSTOP {sp_n($2); check_block_sub $3 $4; new_pesp M_unknown (if $5.any.expr = [] then P_tok else P_call_no_paren) (call(Deref(I_func, $1.any), anonymous_sub None $3 :: $5.any.expr)) $1 $5} /* map { foo } @bar */
+| word BRACKET lines BRACKET_END listexpr %prec LSTOP {sp_n($2); check_block_sub $3 $4; call_and_context(Deref(I_func, $1.any), anonymous_sub None $3 :: $5.any.expr) (if $5.any.expr = [] then P_tok else P_call_no_paren) $1 $5} /* map { foo } @bar */
 | word BRACKET BRACKET expr BRACKET_END            BRACKET_END listexpr %prec LSTOP {sp_n($2); sp_p($3); sp_p($4); sp_p($5); sp_p($6); new_pesp M_unknown (if $7.any.expr = [] then P_tok else P_call_no_paren) (call(Deref(I_func, $1.any), anonymous_sub None (new_esp (M_ref M_hash) [ Ref(I_hash, $4.any.expr) ] $4 $4) :: $7.any.expr)) $1 $7} /* map { { foo } } @bar */
 | word BRACKET BRACKET expr BRACKET_END semi_colon BRACKET_END listexpr %prec LSTOP {sp_n($2); sp_p($3); sp_p($4); sp_p($5); sp_p($7); new_pesp M_unknown (if $8.any.expr = [] then P_tok else P_call_no_paren) (call(Deref(I_func, $1.any), anonymous_sub None (new_esp (M_ref M_hash) [ Ref(I_hash, $4.any.expr); Semi_colon ] $4 $4) :: $8.any.expr)) $1 $8} /* map { { foo }; } @bar */
 
@@ -334,12 +338,12 @@ term:
 | NEW word terminal { die_rule "you must parenthesize parameters: \"new Class(...)\" instead of \"new Class ...\"" }
 | NEW word variable { die_rule "you must parenthesize parameters: \"new Class(...)\" instead of \"new Class ...\"" }
 
-| PRINT { to_Call_op_ M_int P_call_no_paren $1.any (var_STDOUT :: [ var_dollar_ (get_pos $1) ]) $1 $1}
-| PRINT argexpr {check_parenthesized_first_argexpr  $1.any $2; to_Call_op_ M_int P_call_no_paren $1.any (var_STDOUT :: $2.any.expr) $1 $2}
-| PRINT_TO_SCALAR         { to_Call_op_ M_int P_call_no_paren (fst $1.any) (var_STDOUT :: [ Deref(I_scalar, Ident(None, snd $1.any, get_pos $1)) ]) $1 $1}
-| PRINT_TO_SCALAR argexpr { to_Call_op_ M_int P_call_no_paren (fst $1.any) (Deref(I_scalar, Ident(None, snd $1.any, get_pos $1)) :: $2.any.expr) $1 $2}
-| PRINT_TO_STAR           { to_Call_op_ M_int P_call_no_paren (fst $1.any) (Deref(I_star, Ident(None, snd $1.any, get_pos $1)) :: [ var_dollar_ (get_pos $1) ]) $1 $1}
-| PRINT_TO_STAR argexpr   { to_Call_op_ M_int P_call_no_paren (fst $1.any) (Deref(I_star, Ident(None, snd $1.any, get_pos $1)) :: $2.any.expr) $1 $2}
+| PRINT { to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren $1.any (var_STDOUT :: [ var_dollar_ (get_pos $1) ]) $1 $1}
+| PRINT argexpr {check_parenthesized_first_argexpr  $1.any $2; to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren $1.any (var_STDOUT :: $2.any.expr) $1 $2}
+| PRINT_TO_SCALAR         { to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren (fst $1.any) (var_STDOUT :: [ Deref(I_scalar, Ident(None, snd $1.any, get_pos $1)) ]) $1 $1}
+| PRINT_TO_SCALAR argexpr { to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren (fst $1.any) (Deref(I_scalar, Ident(None, snd $1.any, get_pos $1)) :: $2.any.expr) $1 $2}
+| PRINT_TO_STAR           { to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren (fst $1.any) (Deref(I_star, Ident(None, snd $1.any, get_pos $1)) :: [ var_dollar_ (get_pos $1) ]) $1 $1}
+| PRINT_TO_STAR argexpr   { to_Call_op_ (M_mixed [M_int; M_none]) P_call_no_paren (fst $1.any) (Deref(I_star, Ident(None, snd $1.any, get_pos $1)) :: $2.any.expr) $1 $2}
 
 | hash PKG_SCOPE {sp_0($2); new_pesp M_hash P_tok (Call(Too_complex, [$1.any])) $1 $2} /* %main:: */
 
@@ -351,18 +355,18 @@ terminal:
 | STRING {new_1pesp P_tok (to_String true $1) $1}
 | RAW_STRING {new_1pesp P_tok (to_Raw_string $1) $1}
 | REVISION {new_1pesp P_tok (to_Raw_string $1) $1}
-| COMMAND_STRING {to_Call_op_ (M_mixed(M_string, M_list)) P_tok "``" [to_String false $1] $1 $1}
+| COMMAND_STRING {to_Call_op_ (M_mixed[M_string; M_list]) P_tok "``" [to_String false $1] $1 $1}
 | QUOTEWORDS {to_Call_op_ M_list P_tok "qw" [to_Raw_string $1] $1 $1}
 | HERE_DOC {new_1pesp P_tok (to_String false (new_1esp (fst $1.any) $1)) $1 }
 | RAW_HERE_DOC {new_1pesp P_tok (Raw_string(fst $1.any, raw_pos2pos (snd $1.any))) $1}
 | QR_PATTERN {to_Call_op_ M_string P_tok "qr//" (from_PATTERN $1) $1 $1}
 | PATTERN {to_Call_op_ M_array P_expr "m//" (var_dollar_ (get_pos $1) :: from_PATTERN $1) $1 $1}
-| PATTERN_SUBST {to_Call_op_ M_int P_expr "s///" (var_dollar_ (get_pos $1) :: from_PATTERN_SUBST $1) $1 $1}
+| PATTERN_SUBST {to_Call_op_ (M_mixed[M_none; M_int]) P_expr "s///" (var_dollar_ (get_pos $1) :: from_PATTERN_SUBST $1) $1 $1}
 | diamond {new_1pesp P_expr $1.any $1}
 
 diamond:
-| LT GT {sp_0($2); to_Call_op (M_mixed(M_string, M_list)) "<>" [] $1 $2}
-| LT term GT {sp_0($2); sp_0($3); to_Call_op (M_mixed(M_string, M_list)) "<>" [$2.any.expr] $1 $3}
+| LT GT {sp_0($2); to_Call_op (M_mixed[M_string; M_list]) "<>" [] $1 $2}
+| LT term GT {sp_0($2); sp_0($3); to_Call_op (M_mixed[M_string; M_list]) "<>" [$2.any.expr] $1 $3}
 
 subscripted: /* Some kind of subscripted expression */
 | variable PKG_SCOPE bracket_subscript {sp_0($2); sp_0($3); new_esp M_unknown (Call(Too_complex, [$3.any])) $1 $3} /* $foo::{something} */
@@ -370,18 +374,18 @@ subscripted: /* Some kind of subscripted expression */
 | scalar arrayref                      {sp_0($2); check_scalar_subscripted $1; new_esp M_scalar (to_Deref_with(I_array, I_scalar, from_scalar $1, only_one_array_ref $2)) $1 $2} /* $array[$element] */
 | term ARROW bracket_subscript         {sp_0($2); sp_0($3); check_arrow_needed $1 $2; new_esp M_scalar (to_Deref_with(I_hash , I_scalar, $1.any.expr, $3.any               )) $1 $3} /* somehref->{bar} */
 | term ARROW arrayref                  {sp_0($2); sp_0($3); check_arrow_needed $1 $2; new_esp M_scalar (to_Deref_with(I_array, I_scalar, $1.any.expr, only_one_array_ref $3)) $1 $3} /* somearef->[$element] */
-| term ARROW parenthesized             {sp_0($2); sp_0($3); new_esp M_scalar (to_Deref_with(I_func , I_scalar, $1.any.expr, List($3.any.expr))) $1 $3} /* $subref->(@args) */
-| subscripted bracket_subscript        {sp_0($2); new_esp M_scalar (to_Deref_with(I_hash , I_scalar, $1.any, $2.any               )) $1 $2} /* $foo->[bar]{baz} */
-| subscripted arrayref                 {sp_0($2); new_esp M_scalar (to_Deref_with(I_array, I_scalar, $1.any, only_one_array_ref $2)) $1 $2} /* $foo->[$bar][$baz] */
-| subscripted parenthesized            {sp_0($2); new_esp M_scalar (to_Deref_with(I_func , I_scalar, $1.any, List($2.any.expr))) $1 $2} /* $foo->{bar}(@args) */
+| term ARROW parenthesized             {sp_0($2); sp_0($3); new_esp M_unknown (to_Deref_with(I_func , I_scalar, $1.any.expr, List($3.any.expr))) $1 $3} /* $subref->(@args) */
+| subscripted bracket_subscript        {sp_0($2); new_esp M_scalar  (to_Deref_with(I_hash , I_scalar, $1.any, $2.any               )) $1 $2} /* $foo->[bar]{baz} */
+| subscripted arrayref                 {sp_0($2); new_esp M_scalar  (to_Deref_with(I_array, I_scalar, $1.any, only_one_array_ref $2)) $1 $2} /* $foo->[$bar][$baz] */
+| subscripted parenthesized            {sp_0($2); new_esp M_unknown (to_Deref_with(I_func , I_scalar, $1.any, List($2.any.expr))) $1 $2} /* $foo->{bar}(@args) */
 
 restricted_subscripted: /* Some kind of subscripted expression */
 | variable PKG_SCOPE bracket_subscript {sp_0($2); sp_0($3); new_esp M_unknown (Call(Too_complex, [$3.any])) $1 $3} /* $foo::{something} */
 | scalar bracket_subscript             {sp_0($2); check_scalar_subscripted $1; new_esp M_scalar (to_Deref_with(I_hash , I_scalar, from_scalar $1, $2.any               )) $1 $2} /* $foo{bar} */
 | scalar arrayref                      {sp_0($2); check_scalar_subscripted $1; new_esp M_scalar (to_Deref_with(I_array, I_scalar, from_scalar $1, only_one_array_ref $2)) $1 $2} /* $array[$element] */
-| restricted_subscripted bracket_subscript        {sp_0($2); new_esp M_scalar (to_Deref_with(I_hash , I_scalar, $1.any, $2.any               )) $1 $2} /* $foo->[bar]{baz} */
-| restricted_subscripted arrayref                 {sp_0($2); new_esp M_scalar (to_Deref_with(I_array, I_scalar, $1.any, only_one_array_ref $2)) $1 $2} /* $foo->[$bar][$baz] */
-| restricted_subscripted parenthesized            {sp_0($2); new_esp M_scalar (to_Deref_with(I_func , I_scalar, $1.any, List($2.any.expr))) $1 $2} /* $foo->{bar}(@args) */
+| restricted_subscripted bracket_subscript        {sp_0($2); new_esp M_scalar  (to_Deref_with(I_hash , I_scalar, $1.any, $2.any               )) $1 $2} /* $foo->[bar]{baz} */
+| restricted_subscripted arrayref                 {sp_0($2); new_esp M_scalar  (to_Deref_with(I_array, I_scalar, $1.any, only_one_array_ref $2)) $1 $2} /* $foo->[$bar][$baz] */
+| restricted_subscripted parenthesized            {sp_0($2); new_esp M_unknown (to_Deref_with(I_func , I_scalar, $1.any, List($2.any.expr))) $1 $2} /* $foo->{bar}(@args) */
 
 arrayref:
 | arrayref_start ARRAYREF_END {sp_0($2); new_esp (M_ref M_array) $1.any $1 $2}
@@ -404,17 +408,17 @@ my_our: /* Things that can be "my"'d */
 | my_our_paren SCALAR_IDENT PAREN_END {(if snd $1.any = [] then sp_0 else sp_1)($2); check_my_our_paren $1; new_esp M_none (My_our(sndfst $1.any, snd $1.any @ [I_scalar, snd $2.any], pos_range $1 $3)) $1 $3}
 | my_our_paren HASH_IDENT   PAREN_END {(if snd $1.any = [] then sp_0 else sp_1)($2); check_my_our_paren $1; new_esp M_none (My_our(sndfst $1.any, snd $1.any @ [I_hash,   snd $2.any], pos_range $1 $3)) $1 $3}
 | my_our_paren ARRAY_IDENT  PAREN_END {(if snd $1.any = [] then sp_0 else sp_1)($2); check_my_our_paren $1; new_esp M_none (My_our(sndfst $1.any, snd $1.any @ [I_array,  snd $2.any], pos_range $1 $3)) $1 $3}
-| MY_OUR SCALAR_IDENT {new_esp M_scalar (My_our($1.any, [I_scalar, snd $2.any], get_pos $2)) $1 $2}
-| MY_OUR HASH_IDENT   {new_esp M_hash   (My_our($1.any, [I_hash,   snd $2.any], get_pos $2)) $1 $2}
-| MY_OUR ARRAY_IDENT  {new_esp M_array  (My_our($1.any, [I_array,  snd $2.any], get_pos $2)) $1 $2}
+| MY_OUR SCALAR_IDENT {new_esp (M_mixed [M_scalar; M_none]) (My_our($1.any, [I_scalar, snd $2.any], get_pos $2)) $1 $2}
+| MY_OUR HASH_IDENT   {new_esp (M_mixed [M_hash  ; M_none]) (My_our($1.any, [I_hash,   snd $2.any], get_pos $2)) $1 $2}
+| MY_OUR ARRAY_IDENT  {new_esp (M_mixed [M_array ; M_none]) (My_our($1.any, [I_array,  snd $2.any], get_pos $2)) $1 $2}
 
 my_our_paren:
 | MY_OUR PAREN {sp_1($2); new_esp M_special ((true, $1.any), []) $1 $2}
-| my_our_paren comma {if fstfst $1.any then die_rule "syntax error"; new_esp M_special ((true, sndfst $1.any), snd $1.any) $1 $2}
-| my_our_paren BAREWORD {check_my_our_paren $1; if $2.any <> "undef" then die_rule "scalar expected"; new_esp M_special ((false, sndfst $1.any), snd $1.any @ [I_raw, $2.any]) $1 $2}
-| my_our_paren SCALAR_IDENT {check_my_our_paren $1; new_esp M_special ((false, sndfst $1.any), snd $1.any @ [I_scalar, snd $2.any]) $1 $2}
-| my_our_paren HASH_IDENT   {check_my_our_paren $1; new_esp M_special ((false, sndfst $1.any), snd $1.any @ [I_hash,   snd $2.any]) $1 $2}
-| my_our_paren ARRAY_IDENT  {check_my_our_paren $1; new_esp M_special ((false, sndfst $1.any), snd $1.any @ [I_array,  snd $2.any]) $1 $2}
+| my_our_paren comma {if fstfst $1.any then die_rule "syntax error"; new_esp M_none ((true, sndfst $1.any), snd $1.any) $1 $2}
+| my_our_paren BAREWORD {check_my_our_paren $1; if $2.any <> "undef" then die_rule "scalar expected"; new_esp M_none ((false, sndfst $1.any), snd $1.any @ [I_raw, $2.any]) $1 $2}
+| my_our_paren SCALAR_IDENT {check_my_our_paren $1; new_esp M_none ((false, sndfst $1.any), snd $1.any @ [I_scalar, snd $2.any]) $1 $2}
+| my_our_paren HASH_IDENT   {check_my_our_paren $1; new_esp M_none ((false, sndfst $1.any), snd $1.any @ [I_hash,   snd $2.any]) $1 $2}
+| my_our_paren ARRAY_IDENT  {check_my_our_paren $1; new_esp M_none ((false, sndfst $1.any), snd $1.any @ [I_array,  snd $2.any]) $1 $2}
 
 termdo: /* Things called with "do" */
 | DO term %prec UNIOP { die_rule "\"do EXPR\" not allowed" } /* do $filename */
diff --git a/perl_checker.src/parser_helper.ml b/perl_checker.src/parser_helper.ml
index fb8ba16..c7290f5 100644
--- a/perl_checker.src/parser_helper.ml
+++ b/perl_checker.src/parser_helper.ml
@@ -327,7 +327,7 @@ let word_alone esp =
       | "split" -> M_array
       | "shift" -> M_scalar
       | "die" | "return" | "redo" | "next" | "last" -> M_unknown
-      | "caller" -> M_mixed(M_string, M_list)
+      | "caller" -> M_mixed [M_string ; M_list]
 	    
       | "ref" -> M_ref M_scalar
       | _ -> M_unknown
@@ -770,6 +770,20 @@ let call_func is_a_func (e, para) =
 
 let call(e, para) = call_func false (e, para)
 
+let call_and_context(e, para) priority esp_start esp_end =
+  let context = 
+    match e with
+    | Deref(I_func, Ident(None, f, _)) ->
+	(match f with
+	| "map" | "grep" | "grep_index" | "map_index" | "partition" -> M_list
+	| "find" -> M_scalar
+	| "any" | "every" -> M_scalar
+	| "find_index" -> M_int
+	| "each_index" -> M_none
+	| _ -> M_unknown)
+    | _ -> M_unknown
+  in
+  new_pesp context priority (call(e, para)) esp_start esp_end
 
 let call_one_scalar_para { any = e ; pos = pos } para esp_start esp_end =
   let para =
@@ -880,7 +894,7 @@ let rec mcontext2s = function
 
   | M_special -> "special"
   | M_unknown -> "unknown"
-  | M_mixed(a, b) -> mcontext2s a ^ " | " ^ mcontext2s b
+  | M_mixed l -> String.concat " | " (List.map mcontext2s l)
 
 let mcontext_is_scalar = function
   | M_int | M_float | M_string | M_ref _ | M_revision
@@ -910,24 +924,44 @@ let rec mcontext_lower c1 c2 =
     -> true
 
   | M_ref a, M_ref b -> mcontext_lower a b
-  | M_mixed(c1, c2), M_mixed(a, b) -> mcontext_lower c1 a && mcontext_lower c2 b || mcontext_lower c2 a && mcontext_lower c1 b
-  | c, M_mixed(a, b) -> mcontext_lower c a || mcontext_lower c b
+  | c, M_mixed l -> List.exists (mcontext_lower c) l
+  | M_mixed l, c -> List.exists (fun a -> mcontext_lower a c) l
 
   | _ -> false
 
-let mcontext_merge c1 c2 =
-  if mcontext_lower c1 c2 then c2 else
-  if mcontext_lower c2 c1 then c1 else
+let mcontext_merge_raw c1 c2 =
   match c1, c2 with
-  | M_unknown, _ | _, M_unknown -> internal_error "mcontext_merge1"
-  | M_mixed _, _ | _, M_mixed _ -> internal_error "TODO: complex mcontext_merge"
+  | M_unknown, _ | _, M_unknown -> Some M_unknown
+  | M_mixed _, _ | _, M_mixed _ -> internal_error "mcontext_merge_raw"
   | _ -> 
+      (*
+      if mcontext_lower c1 c2 then Some c2 else
+      if mcontext_lower c2 c1 then Some c1 else
+       *)
+      if c1 = c2 then Some c1 else
       if mcontext_is_scalar c1 && mcontext_is_scalar c2 
-      then M_scalar 
-      else M_mixed(c1, c2)
-let mcontext_lmerge = function
+      then Some M_scalar 
+      else None
+
+let rec mcontext_lmerge_add l = function
+  | M_mixed l2 -> List.fold_left mcontext_lmerge_add [] (l2 @ l)
+  | c ->
+      let rec add_to = function
+	| [] -> [c]
+	| M_mixed subl :: l -> add_to (subl @ l)
+	| c2 :: l ->
+	    match mcontext_merge_raw c c2 with
+	    | Some c' -> c' :: l
+	    | None -> c2 :: add_to l
+      in add_to l
+
+let mcontext_lmerge l =
+  match List.fold_left mcontext_lmerge_add [] l with
   | [] -> internal_error "mcontext_lmerge"
-  | e :: l -> List.fold_left mcontext_merge e l
+  | [c] -> c
+  | l -> M_mixed l
+
+let mcontext_merge c1 c2 = mcontext_lmerge [ c1 ; c2 ]
 
 let mcontext_lmaybe esp = if esp.any = [] then [] else [esp.mcontext]
 
@@ -940,6 +974,9 @@ let mcontext_check_raw wanted_mcontext esp f_lower f_greater f_err =
     (warn_rule (sprintf "context %s is not compatible with context %s" (mcontext2s esp.mcontext) (mcontext2s wanted_mcontext)); 
      f_err())
 
+let mcontext_check wanted_mcontext esp =
+  mcontext_check_raw wanted_mcontext esp (fun () -> ()) (fun () -> ()) (fun () -> ())
+
 let mcontext_symops wanted_mcontext esp1 esp2 =
   mcontext_check_raw wanted_mcontext esp1 
     (fun () ->
@@ -957,10 +994,28 @@ let mcontext_symops wanted_mcontext esp1 esp2 =
 	(fun () -> wanted_mcontext))
     (fun () -> wanted_mcontext)
 
-let mcontext_check wanted_mcontext esp =
-  mcontext_check_raw wanted_mcontext esp (fun () -> ()) (fun () -> ()) (fun () -> ())
+let mcontext_rightops wanted_mcontext esp1 esp2 = 
+  mcontext_check wanted_mcontext esp1 ;
+  mcontext_check_raw wanted_mcontext esp2 (fun () -> esp2.mcontext) (fun () -> wanted_mcontext) (fun () -> wanted_mcontext)
 
 let mcontext_unop wanted_mcontext esp = mcontext_check wanted_mcontext esp ; wanted_mcontext
 
 let mcontext_check_non_none esp =
   if esp.mcontext = M_none then warn_rule "() context not accepted here"
+
+let mcontext_check_none esp =
+  match esp.mcontext with
+  | M_none | M_unknown -> ()
+  | M_mixed l when List.exists (fun c -> c = M_none) l -> ()
+  | _ -> 
+      match esp.any with
+      | [List [Num("1", _)]; Semi_colon] -> () (* allow "1;" for package return value. It would be much better to check we are at toplevel, but hell i don't want to wire this information up to here *)
+      | [List [Call_op ("<>", [Ident (None, "STDIN", _)], _)]; Semi_colon] -> () (* allow <STDIN> to ask "press return" *)
+      | _ -> warn_rule "value is dropped"
+
+let mcontext_op_assign left right =
+  mcontext_check_non_none right;
+
+  match left.any.expr with
+  | Deref(I_array, _) | My_our("my", [(I_array, _)], _) -> M_mixed [ M_array; M_none ]
+  | _ -> mcontext_merge right.mcontext M_none
diff --git a/perl_checker.src/parser_helper.mli b/perl_checker.src/parser_helper.mli
index 77fef90..09a6a0e 100644
--- a/perl_checker.src/parser_helper.mli
+++ b/perl_checker.src/parser_helper.mli
@@ -184,6 +184,12 @@ val generate_pot : string -> unit
 val call_func :
   bool -> Types.fromparser * Types.fromparser list -> Types.fromparser
 val call : Types.fromparser * Types.fromparser list -> Types.fromparser
+val call_and_context :
+  Types.fromparser * Types.fromparser list ->
+  Types.priority ->
+  'a Types.any_spaces_pos ->
+  'b Types.any_spaces_pos ->
+  Types.fromparser Types.prio_anyexpr Types.any_spaces_pos
 val call_one_scalar_para :
   string Types.any_spaces_pos ->
   Types.fromparser list ->
@@ -225,19 +231,30 @@ val from_PATTERN_SUBST :
 val mcontext2s : Types.maybe_context -> string
 val mcontext_is_scalar : Types.maybe_context -> bool
 val mcontext_lower : Types.maybe_context -> Types.maybe_context -> bool
+val mcontext_merge_raw :
+  Types.maybe_context -> Types.maybe_context -> Types.maybe_context option
+val mcontext_lmerge_add :
+  Types.maybe_context list -> Types.maybe_context -> Types.maybe_context list
+val mcontext_lmerge : Types.maybe_context list -> Types.maybe_context
 val mcontext_merge :
   Types.maybe_context -> Types.maybe_context -> Types.maybe_context
-val mcontext_lmerge : Types.maybe_context list -> Types.maybe_context
 val mcontext_lmaybe :
   'a list Types.any_spaces_pos -> Types.maybe_context list
 val mcontext_check_raw :
   Types.maybe_context ->
   'a Types.any_spaces_pos ->
   (unit -> 'b) -> (unit -> 'b) -> (unit -> 'b) -> 'b
+val mcontext_check : Types.maybe_context -> 'a Types.any_spaces_pos -> unit
 val mcontext_symops :
   Types.maybe_context ->
   'a Types.any_spaces_pos -> 'b Types.any_spaces_pos -> Types.maybe_context
-val mcontext_check : Types.maybe_context -> 'a Types.any_spaces_pos -> unit
+val mcontext_rightops :
+  Types.maybe_context ->
+  'a Types.any_spaces_pos -> 'b Types.any_spaces_pos -> Types.maybe_context
 val mcontext_unop :
   Types.maybe_context -> 'a Types.any_spaces_pos -> Types.maybe_context
 val mcontext_check_non_none : 'a Types.any_spaces_pos -> unit
+val mcontext_check_none : Types.fromparser list Types.any_spaces_pos -> unit
+val mcontext_op_assign :
+  Types.fromparser Types.prio_anyexpr Types.any_spaces_pos ->
+  'a Types.any_spaces_pos -> Types.maybe_context
diff --git a/perl_checker.src/types.mli b/perl_checker.src/types.mli
index 1a33d20..d9bda2c 100644
--- a/perl_checker.src/types.mli
+++ b/perl_checker.src/types.mli
@@ -25,7 +25,7 @@ type maybe_context =
 
   | M_special
   | M_unknown
-  | M_mixed of maybe_context * maybe_context
+  | M_mixed of maybe_context list
 
 type fromparser = 
    | Undef