Module: Mesa Branch: master Commit: 73620709c9dce79e58bd0d29be95c658ac95779b URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=73620709c9dce79e58bd0d29be95c658ac95779b
Author: Kenneth Graunke <[email protected]> Date: Fri Jul 12 23:10:14 2013 -0700 glsl: Silence the last shift/reduce conflict warning in the grammar. The single remaining shift/reduce conflict was the classic ELSE problem: 292 selection_rest_statement: statement . ELSE statement 293 | statement . ELSE shift, and go to state 479 ELSE [reduce using rule 293 (selection_rest_statement)] $default reduce using rule 293 (selection_rest_statement) The correct behavior here is to shift, which is what happens by default. However, resolving it explicitly will make it possible to fail the build on new errors, making them much easier to detect. The classic way to solve this is to use right associativity: http://www.gnu.org/software/bison/manual/html_node/Non-Operators.html Since there is no THEN token in GLSL, we need to fake one. %right THEN creates a new terminal symbol; the %prec directive says to use the precedence of that terminal. Signed-off-by: Kenneth Graunke <[email protected]> Reviewed-by: Chris Forbes <[email protected]> --- src/glsl/glsl_parser.yy | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/src/glsl/glsl_parser.yy b/src/glsl/glsl_parser.yy index 78f5bf6..e4b7ff7 100644 --- a/src/glsl/glsl_parser.yy +++ b/src/glsl/glsl_parser.yy @@ -248,6 +248,8 @@ static void yyerror(YYLTYPE *loc, _mesa_glsl_parse_state *st, const char *msg) %type <node> for_init_statement %type <for_rest_statement> for_rest_statement %type <n> integer_constant + +%right THEN ELSE %% translation_unit: @@ -1738,7 +1740,7 @@ selection_rest_statement: $$.then_statement = $1; $$.else_statement = $3; } - | statement + | statement %prec THEN { $$.then_statement = $1; $$.else_statement = NULL; _______________________________________________ mesa-commit mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-commit
