From: Joel E. Denny Date: Wed, 1 Nov 2006 06:09:40 +0000 (+0000) Subject: Disable unset/unused mid-rule value warnings by default, and recognize X-Git-Tag: v2.3b~249 X-Git-Url: https://git.saurik.com/bison.git/commitdiff_plain/17bd8a736a491f4867176b3885e39e74dc07f854 Disable unset/unused mid-rule value warnings by default, and recognize --warnings=midrule-values to enable them. Discussed starting at . * NEWS (2.3a+): Mention. * src/getargs.c, src/getargs.h (warnings_args, warnings_types, enum warnings): Add entry for midrule-values subargument. * src/reader.c (symbol_should_be_used): Don't return true just because the value is a set/used mid-rule value unless --warnings=midrule-values was specified. * tests/input.at (Unused values, Unused values before symbol declarations): Run tests with and without --warnings=midrule-values. * src/reader.c (check_and_convert_grammar): Use symbol_list_free rather than LIST_FREE directly. --- diff --git a/ChangeLog b/ChangeLog index 54906055..f4fb9918 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,20 @@ +2006-10-31 Joel E. Denny + + Disable unset/unused mid-rule value warnings by default, and recognize + --warnings=midrule-values to enable them. Discussed starting at + . + * NEWS (2.3a+): Mention. + * src/getargs.c, src/getargs.h (warnings_args, warnings_types, enum + warnings): Add entry for midrule-values subargument. + * src/reader.c (symbol_should_be_used): Don't return true just because + the value is a set/used mid-rule value unless + --warnings=midrule-values was specified. + * tests/input.at (Unused values, Unused values before symbol + declarations): Run tests with and without --warnings=midrule-values. + + * src/reader.c (check_and_convert_grammar): Use symbol_list_free rather + than LIST_FREE directly. + 2006-10-31 Joel E. Denny Finish implementing --warnings=error, which should not be implied by diff --git a/NEWS b/NEWS index c3fe6d03..b1371ae7 100644 --- a/NEWS +++ b/NEWS @@ -6,6 +6,26 @@ Changes in version 2.3a+ (????-??-??): * The -g and --graph options now output graphs in Graphviz DOT format, not VCG format. +* Revised warning: unset or unused mid-rule values + + Since Bison 2.2, Bison has warned about mid-rule values that are set but not + used within any of the actions of the parent rule. For example, Bison warns + about unused $2 in: + + exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; }; + + Now, Bison also warns about mid-rule values that are used but not set. For + example, Bison warns about unset $$ in the mid-rule action in: + + exp: '1' { $1 = 1; } '+' exp { $$ = $2 + $4; }; + + However, Bison now disables both of these warnings by default since they + sometimes prove to be false alarms in existing grammars employing the Yacc + constructs $0 or $-N (where N is some positive integer). + + To enable these warnings, specify the flag `--warnings=midrule-values' or + `-W', which is a synonym for `--warnings=all'. + * Bison now recognizes two separate kinds of default %destructor's and %printer's: diff --git a/src/getargs.c b/src/getargs.c index c34efa21..177255e7 100644 --- a/src/getargs.c +++ b/src/getargs.c @@ -203,16 +203,18 @@ static const char * const warnings_args[] = { /* In a series of synonyms, present the most meaningful first, so that argmatch_valid be more readable. */ - "none - no warnings", - "yacc - incompatibilities with POSIX YACC", - "all - all of the above", - "error - warnings are errors", + "none - no warnings", + "midrule-values - unset or unused midrule values", + "yacc - incompatibilities with POSIX YACC", + "all - all of the above", + "error - warnings are errors", 0 }; static const int warnings_types[] = { warnings_none, + warnings_midrule_values, warnings_yacc, warnings_all, warnings_error diff --git a/src/getargs.h b/src/getargs.h index d0fa12f2..a84a4857 100644 --- a/src/getargs.h +++ b/src/getargs.h @@ -111,7 +111,8 @@ enum warnings { warnings_none = 0, /**< Issue no warnings. */ warnings_error = 1 << 0, /**< Warnings are treated as errors. */ - warnings_yacc = 1 << 1, /**< POSIXME. */ + warnings_midrule_values = 1 << 1, /**< Unset or unused midrule values. */ + warnings_yacc = 1 << 2, /**< POSIXME. */ warnings_all = ~warnings_error /**< All above warnings. */ }; /** What warnings are issued. */ diff --git a/src/reader.c b/src/reader.c index 1066bb5b..d5cd629f 100644 --- a/src/reader.c +++ b/src/reader.c @@ -243,19 +243,24 @@ grammar_current_rule_begin (symbol *lhs, location loc) /*----------------------------------------------------------------------. -| A symbol should be used if it has a destructor, or if it is a | -| mid-rule symbol (i.e., the generated LHS replacing a mid-rule | -| action) that was assigned to, as in "exp: { $$ = 1; } { $$ = $1; }". | +| A symbol should be used if either: | +| 1. It has a destructor. | +| 2. --warnings=midrule-values and the symbol is a mid-rule symbol | +| (i.e., the generated LHS replacing a mid-rule action) that was | +| assigned to or used, as in "exp: { $$ = 1; } { $$ = $1; }". | `----------------------------------------------------------------------*/ static bool symbol_should_be_used (symbol_list const *s) { - return (symbol_destructor_get (s->content.sym) - || (s->midrule && s->midrule->used) - || (s->midrule_parent_rule - && symbol_list_n_get (s->midrule_parent_rule, - s->midrule_parent_rhs_index)->used)); + if (symbol_destructor_get (s->content.sym)) + return true; + if (warnings_flag & warnings_midrule_values) + return ((s->midrule && s->midrule->used) + || (s->midrule_parent_rule + && symbol_list_n_get (s->midrule_parent_rule, + s->midrule_parent_rhs_index)->used)); + return false; } /*----------------------------------------------------------------. @@ -666,5 +671,5 @@ check_and_convert_grammar (void) packgram (); /* The grammar as a symbol_list is no longer needed. */ - LIST_FREE (symbol_list, grammar); + symbol_list_free (grammar); } diff --git a/tests/input.at b/tests/input.at index dec1cbe6..1239df00 100644 --- a/tests/input.at +++ b/tests/input.at @@ -80,13 +80,15 @@ m4_define([_AT_UNUSED_VALUES_DECLARATIONS], %destructor { destroy ($$); } INT a b c d e f g h i j k l;]]]) -# AT_CHECK_UNUSED_VALUES(DECLARATIONS_AFTER) -# -------------------------------------------- +# AT_CHECK_UNUSED_VALUES(DECLARATIONS_AFTER, CHECK_MIDRULE_VALUES) +# ------------------------------------------------------------------ # Generate a grammar to test unused values, # compile it, run it. If DECLARATIONS_AFTER # is set, then the token, type, and destructor # declarations are generated after the rules -# rather than before. +# rather than before. If CHECK_MIDRULE_VALUES +# is set, then --warnings=midrule-values is +# set. m4_define([AT_CHECK_UNUSED_VALUES], [AT_DATA([input.y], @@ -116,19 +118,19 @@ l: INT | INT { $$ = $1; } INT { $$ = $2 + $< _AT_UNUSED_VALUES_DECLARATIONS]) ) -AT_CHECK([bison input.y], [0], [], +AT_CHECK([bison]m4_ifval($2, [ --warnings=midrule-values ])[ input.y], [0], [], [[input.y:11.10-32: warning: unset value: $]$[ input.y:11.10-32: warning: unused value: $]1[ input.y:11.10-32: warning: unused value: $]3[ input.y:11.10-32: warning: unused value: $]5[ input.y:12.9: warning: empty rule for typed nonterminal, and no action -input.y:13.14-19: warning: unset value: $$ +]]m4_ifval($2, [[[input.y:13.14-19: warning: unset value: $$ input.y:13.25-39: warning: unset value: $$ -input.y:13.10-59: warning: unset value: $]$[ +]]])[[input.y:13.10-59: warning: unset value: $]$[ input.y:13.10-59: warning: unused value: $]3[ input.y:13.10-59: warning: unused value: $]5[ -input.y:14.14-16: warning: unset value: $$ -input.y:14.10-47: warning: unset value: $]$[ +]]m4_ifval($2, [[[input.y:14.14-16: warning: unset value: $$ +]]])[[input.y:14.10-47: warning: unset value: $]$[ input.y:14.10-47: warning: unused value: $]3[ input.y:14.10-47: warning: unused value: $]5[ input.y:15.10-36: warning: unset value: $]$[ @@ -136,21 +138,21 @@ input.y:15.10-36: warning: unused value: $]3[ input.y:15.10-36: warning: unused value: $]5[ input.y:17.10-58: warning: unset value: $]$[ input.y:17.10-58: warning: unused value: $]1[ -input.y:17.10-58: warning: unused value: $]2[ -input.y:17.10-58: warning: unused value: $]3[ -input.y:17.10-58: warning: unused value: $]4[ -input.y:17.10-58: warning: unused value: $]5[ +]]m4_ifval($2, [[[input.y:17.10-58: warning: unused value: $]2[ +]]])[[input.y:17.10-58: warning: unused value: $]3[ +]]m4_ifval($2, [[[input.y:17.10-58: warning: unused value: $]4[ +]]])[[input.y:17.10-58: warning: unused value: $]5[ input.y:18.10-72: warning: unset value: $]$[ input.y:18.10-72: warning: unused value: $]1[ input.y:18.10-72: warning: unused value: $]3[ -input.y:18.10-72: warning: unused value: $]4[ -input.y:18.10-72: warning: unused value: $]5[ -input.y:20.10-55: warning: unused value: $]3[ -input.y:21.10-68: warning: unset value: $]$[ +]]m4_ifval($2, [[[input.y:18.10-72: warning: unused value: $]4[ +]]])[[input.y:18.10-72: warning: unused value: $]5[ +]]m4_ifval($2, [[[input.y:20.10-55: warning: unused value: $]3[ +]]])[[input.y:21.10-68: warning: unset value: $]$[ input.y:21.10-68: warning: unused value: $]1[ input.y:21.10-68: warning: unused value: $]2[ -input.y:21.10-68: warning: unused value: $]4[ -]])]) +]]m4_ifval($2, [[[input.y:21.10-68: warning: unused value: $]4[ +]]]))]) ## --------------- ## @@ -159,6 +161,7 @@ input.y:21.10-68: warning: unused value: $]4[ AT_SETUP([Unused values]) AT_CHECK_UNUSED_VALUES +AT_CHECK_UNUSED_VALUES(, [1]) AT_CLEANUP @@ -168,6 +171,7 @@ AT_CLEANUP AT_SETUP([Unused values before symbol declarations]) AT_CHECK_UNUSED_VALUES([1]) +AT_CHECK_UNUSED_VALUES([1], [1]) AT_CLEANUP