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Set and test no-warning bit to avoid -Wnonnull for synthesized expressions.

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Resolves:
PR c++/96003 spurious -Wnonnull calling a member on the result of static_cast

gcc/c-family/ChangeLog:

	PR c++/96003
	* c-common.c (check_function_arguments_recurse): Return early when
	no-warning bit is set.

gcc/cp/ChangeLog:

	PR c++/96003
	* class.c (build_base_path): Set no-warning bit on the synthesized
	conditional expression in static_cast.

gcc/testsuite/ChangeLog:

	PR c++/96003
	* g++.dg/warn/Wnonnull7.C: New test.
This commit is contained in:
Martin Sebor 2020-07-31 10:27:33 -06:00
parent 4143efc1ee
commit df5cf47a97
3 changed files with 47 additions and 2 deletions
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3
gcc/c-family/c-common.c
View File

@ -5822,6 +5822,9 @@ check_function_arguments_recurse (void (*callback)
void *ctx, tree param,
unsigned HOST_WIDE_INT param_num)
{
if (TREE_NO_WARNING (param))
return;
if (CONVERT_EXPR_P (param)
&& (TYPE_PRECISION (TREE_TYPE (param))
== TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (param, 0)))))

10
gcc/cp/class.c
View File

@ -516,8 +516,14 @@ build_base_path (enum tree_code code,
out:
if (null_test)
expr = fold_build3_loc (input_location, COND_EXPR, target_type, null_test, expr,
build_zero_cst (target_type));
{
expr = fold_build3_loc (input_location, COND_EXPR, target_type, null_test,
expr, build_zero_cst (target_type));
/* Avoid warning for the whole conditional expression (in addition
to NULL_TEST itself -- see above) in case the result is used in
a nonnull context that the front end -Wnonnull checks. */
TREE_NO_WARNING (expr) = 1;
}
return expr;
}

36
gcc/testsuite/g++.dg/warn/Wnonnull7.C Normal file
View File

@ -0,0 +1,36 @@
/* PR c++/96003 - spurious -Wnonnull calling a member on the result
of static_cast
{ dg-do compile }
{ dg-options "-Wall" } */
struct D;
struct B
{
B* next;
D* Next ();
};
struct D: B
{
virtual ~D ();
};
struct Iterator
{
D* p;
void advance ()
{
p = static_cast<B*>(p)->Next (); // { dg-bogus "\\\[-Wnonnull" }
}
};
// Test case from comment #11.
struct S1 { virtual ~S1 (); };
struct S2 { virtual ~S2 (); };
struct S3: S1, S2 { void f (); };
void f (S2 *p)
{
static_cast<S3 *>(p)->f (); // { dg-bogus "\\\[-Wnonnull" }
}