From dbb68221b64c0174eeb22d878a8e078775ee73bf Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Thu, 10 Sep 2015 15:29:44 +0000 Subject: Warn when comparing nonnull arguments to NULL in a function. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If an argument is marked as nonnull then passing in a NULL argument will produce bad results even if the code checks against NULL. GCC might optimize such checks away so warn the user when the function contains such comparisons. nn.c: In function ‘foo’: nn.c:6:27: warning: nonnull argument ‘bar’ compared to NULL [-Wnonnull] void foo(void *bar) { if (!bar) abort(); } ^ gcc/ChangeLog * doc/invoke.texi (Wnonnull): Also warns when comparing against NULL. gcc/c/ChangeLog * c-typeck.c (build_binary_op): Check and warn when nonnull arg parm against NULL. gcc/cp/ChangeLog * typeck.c (cp_build_binary_op): Check and warn when nonnull arg parm against NULL. gcc/testsuite/ChangeLog * c-c++-common/nonnull-1.c: New test. From-SVN: r227649 --- gcc/c/ChangeLog | 5 +++++ gcc/c/c-typeck.c | 10 ++++++++++ 2 files changed, 15 insertions(+) (limited to 'gcc/c') diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog index cfc20aa..325686a 100644 --- a/gcc/c/ChangeLog +++ b/gcc/c/ChangeLog @@ -1,3 +1,8 @@ +2015-09-09 Mark Wielaard + + * c-typeck.c (build_binary_op): Check and warn when nonnull arg + parm against NULL. + 2015-09-10 Jakub Jelinek PR c/67502 diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c index dc22396..4108f27 100644 --- a/gcc/c/c-typeck.c +++ b/gcc/c/c-typeck.c @@ -10803,6 +10803,11 @@ build_binary_op (location_t location, enum tree_code code, short_compare = 1; else if (code0 == POINTER_TYPE && null_pointer_constant_p (orig_op1)) { + if (warn_nonnull + && TREE_CODE (op0) == PARM_DECL && nonnull_arg_p (op0)) + warning_at (location, OPT_Wnonnull, + "nonnull argument %qD compared to NULL", op0); + if (TREE_CODE (op0) == ADDR_EXPR && decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0))) { @@ -10823,6 +10828,11 @@ build_binary_op (location_t location, enum tree_code code, } else if (code1 == POINTER_TYPE && null_pointer_constant_p (orig_op0)) { + if (warn_nonnull + && TREE_CODE (op1) == PARM_DECL && nonnull_arg_p (op1)) + warning_at (location, OPT_Wnonnull, + "nonnull argument %qD compared to NULL", op1); + if (TREE_CODE (op1) == ADDR_EXPR && decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0))) { -- cgit v1.1