diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e9c077124bd..cb164143b54 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2010-06-24 Andi Kleen + + * c-parser.c (c_parser_conditional_expression): + Call warn_for_omitted_condop. + * doc/invoke.texi: Document omitted condop warning. + 2010-06-24 Nick Clifton * loop-unswitch.c (compare_and_jump_seq): Assert that the last diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog index 96649c4a34e..0d54b2d01fc 100644 --- a/gcc/c-family/ChangeLog +++ b/gcc/c-family/ChangeLog @@ -1,3 +1,8 @@ +2010-06-24 Andi Kleen + + * c-common.c (warn_for_omitted_condop): New. + * c-common.h (warn_for_omitted_condop): Add prototype. + 2010-06-21 Joseph Myers * c.opt (lang-objc): Remove. diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 86c3802b0d2..14675bcf67e 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -8405,6 +8405,18 @@ fold_offsetof (tree expr, tree stop_ref) return convert (size_type_node, fold_offsetof_1 (expr, stop_ref)); } +/* Warn for A ?: C expressions (with B omitted) where A is a boolean + expression, because B will always be true. */ + +void +warn_for_omitted_condop (location_t location, tree cond) +{ + if (truth_value_p (TREE_CODE (cond))) + warning_at (location, OPT_Wparentheses, + "the omitted middle operand in ?: will always be %, " + "suggest explicit middle operand"); +} + /* Print an error message for an invalid lvalue. USE says how the lvalue is being used and so selects the error message. */ diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h index 6948b8231e8..5784746e90a 100644 --- a/gcc/c-family/c-common.h +++ b/gcc/c-family/c-common.h @@ -736,6 +736,7 @@ extern void c_parse_file (void); /* This is misnamed, it actually performs end-of-compilation processing. */ extern void finish_file (void); +extern void warn_for_omitted_condop (location_t, tree); /* These macros provide convenient access to the various _STMT nodes. */ diff --git a/gcc/c-parser.c b/gcc/c-parser.c index 04506df176e..ba184783343 100644 --- a/gcc/c-parser.c +++ b/gcc/c-parser.c @@ -4795,7 +4795,7 @@ static struct c_expr c_parser_conditional_expression (c_parser *parser, struct c_expr *after) { struct c_expr cond, exp1, exp2, ret; - location_t cond_loc, colon_loc; + location_t cond_loc, colon_loc, middle_loc; gcc_assert (!after || c_dialect_objc ()); @@ -4809,8 +4809,11 @@ c_parser_conditional_expression (c_parser *parser, struct c_expr *after) if (c_parser_next_token_is (parser, CPP_COLON)) { tree eptype = NULL_TREE; - pedwarn (c_parser_peek_token (parser)->location, OPT_pedantic, + + middle_loc = c_parser_peek_token (parser)->location; + pedwarn (middle_loc, OPT_pedantic, "ISO C forbids omitting the middle term of a ?: expression"); + warn_for_omitted_condop (middle_loc, cond.value); if (TREE_CODE (cond.value) == EXCESS_PRECISION_EXPR) { eptype = TREE_TYPE (cond.value); diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 95a7138e673..b5ba3bc6e58 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,10 @@ +2010-06-24 Andi Kleen + + * parser.c: (cp_parser_question_colon_clause): + Switch to use cp_lexer_peek_token. + Call warn_for_omitted_condop. Call pedwarn for omitted + middle operand. + 2010-06-22 Jakub Jelinek PR c++/44619 diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index c6f8d7ee769..4e4db2d6d76 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -6815,15 +6815,20 @@ cp_parser_question_colon_clause (cp_parser* parser, tree logical_or_expr) { tree expr; tree assignment_expr; + struct cp_token *token; /* Consume the `?' token. */ cp_lexer_consume_token (parser->lexer); + token = cp_lexer_peek_token (parser->lexer); if (cp_parser_allow_gnu_extensions_p (parser) - && cp_lexer_next_token_is (parser->lexer, CPP_COLON)) + && token->type == CPP_COLON) { + pedwarn (token->location, OPT_pedantic, + "ISO C++ does not allow ?: with omitted middle operand"); /* Implicit true clause. */ expr = NULL_TREE; c_inhibit_evaluation_warnings += logical_or_expr == truthvalue_true_node; + warn_for_omitted_condop (token->location, logical_or_expr); } else { diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 88240fcc19f..3eae7d7a36e 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -3275,6 +3275,12 @@ look like this: @end group @end smallexample +Also warn for dangerous uses of the +?: with omitted middle operand GNU extension. When the condition +in the ?: operator is a boolean expression the omitted value will +be always 1. Often the user expects it to be a value computed +inside the conditional expression instead. + This warning is enabled by @option{-Wall}. @item -Wsequence-point diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 2dbff36f6f3..351dcd8e8d1 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2010-06-24 Andi Kleen + + * c-c++-common/warn-omitted-condop.c: New. + 2010-06-24 Tobias Burnus PR fortran/44614 diff --git a/gcc/testsuite/c-c++-common/warn-ommitted-condop.c b/gcc/testsuite/c-c++-common/warn-ommitted-condop.c new file mode 100644 index 00000000000..de92b8f2cdc --- /dev/null +++ b/gcc/testsuite/c-c++-common/warn-ommitted-condop.c @@ -0,0 +1,29 @@ +/* { dg-options "-Wparentheses" } */ + +extern void f2 (int); + +void bar (int x, int y, int z) +{ +#define T(op) f2 (x op y ? : 1) +#define T2(op) f2 (x op y ? 2 : 1) + + T(<); /* { dg-warning "omitted middle operand" } */ + T(>); /* { dg-warning "omitted middle operand" } */ + T(<=); /* { dg-warning "omitted middle operand" } */ + T(>=); /* { dg-warning "omitted middle operand" } */ + T(==); /* { dg-warning "omitted middle operand" } */ + T(!=); /* { dg-warning "omitted middle operand" } */ + T(||); /* { dg-warning "omitted middle operand" } */ + T(&&); /* { dg-warning "omitted middle operand" } */ + f2 (!x ? : 1); /* { dg-warning "omitted middle operand" } */ + T2(<); /* { dg-bogus "omitted middle operand" } */ + T2(>); /* { dg-bogus "omitted middle operand" } */ + T2(==); /* { dg-bogus "omitted middle operand" } */ + T2(||); /* { dg-bogus "omitted middle operand" } */ + T2(&&); /* { dg-bogus "omitted middle operand" } */ + T(+); /* { dg-bogus "omitted middle operand" } */ + T(-); /* { dg-bogus "omitted middle operand" } */ + T(*); /* { dg-bogus "omitted middle operand" } */ + T(/); /* { dg-bogus "omitted middle operand" } */ + T(^); /* { dg-bogus "omitted middle operand" } */ +}