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| author | Jakub Jelinek <jakub@redhat.com> | 2021-05-25 17:24:38 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-05-25 17:24:38 +0200 |
| commit | ad52d89808a947264397e920d7483090d4108f7b (patch) | |
| tree | 2fdf00fd50be88d58880aed5e5302bdc24c6529e /gcc/cp/call.c | |
| parent | 1d3707a52d6b8a3054248b4291719150937db309 (diff) | |
| download | gcc-ad52d89808a947264397e920d7483090d4108f7b.zip gcc-ad52d89808a947264397e920d7483090d4108f7b.tar.gz gcc-ad52d89808a947264397e920d7483090d4108f7b.tar.bz2 | |
c++: Avoid -Wunused-value false positives on nullptr passed to ellipsis [PR100666]
When passing expressions with decltype(nullptr) type with side-effects to
ellipsis, we pass (void *)0 instead, but for the side-effects evaluate them
on the lhs of a COMPOUND_EXPR. Unfortunately that means we warn about it
if the expression is a call to nodiscard marked function, even when the
result is really used, just needs to be transformed.
Fixed by adding a warning_sentinel.
2021-05-25 Jakub Jelinek <jakub@redhat.com>
PR c++/100666
* call.c (convert_arg_to_ellipsis): For expressions with NULLPTR_TYPE
and side-effects, temporarily disable -Wunused-result warning when
building COMPOUND_EXPR.
* g++.dg/cpp1z/nodiscard8.C: New test.
* g++.dg/cpp1z/nodiscard9.C: New test.
Diffstat (limited to 'gcc/cp/call.c')
| -rw-r--r-- | gcc/cp/call.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/gcc/cp/call.c b/gcc/cp/call.c index cfccf27..3076fe6 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -8178,7 +8178,10 @@ convert_arg_to_ellipsis (tree arg, tsubst_flags_t complain) { arg = mark_rvalue_use (arg); if (TREE_SIDE_EFFECTS (arg)) - arg = cp_build_compound_expr (arg, null_pointer_node, complain); + { + warning_sentinel w(warn_unused_result); + arg = cp_build_compound_expr (arg, null_pointer_node, complain); + } else arg = null_pointer_node; } |