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| author | Patrick Palka <ppalka@redhat.com> | 2024-07-17 20:57:54 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2024-07-17 20:57:54 -0400 |
| commit | 144b6099cdaa9ac1b298687c0cfdb06a970e338b (patch) | |
| tree | 4b893361f04c94d02c8977459bf20dc1c70a07ac | |
| parent | 313afcfdabeab3e6705ac0bd1273627075be0023 (diff) | |
| download | gcc-144b6099cdaa9ac1b298687c0cfdb06a970e338b.zip gcc-144b6099cdaa9ac1b298687c0cfdb06a970e338b.tar.gz gcc-144b6099cdaa9ac1b298687c0cfdb06a970e338b.tar.bz2 | |
c++: missing -Wunused-value for !<expr> [PR114104]
Here we're neglecting to issue a -Wunused-value warning for suitable !
operator expressions, and in turn for != operator expressions that are
rewritten as !(x == y), only because we don't call warn_if_unused_value
on TRUTH_NOT_EXPR since its class is tcc_expression. This patch makes
us also consider warning for TRUTH_NOT_EXPR and also for ADDR_EXPR.
PR c++/114104
gcc/cp/ChangeLog:
* cvt.cc (convert_to_void): Call warn_if_unused_value for
TRUTH_NOT_EXPR and ADDR_EXPR as well.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wunused-20.C: New test.
Reviewed-by: Jason Merrill <jason@redhat.com>
| -rw-r--r-- | gcc/cp/cvt.cc | 2 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/warn/Wunused-20.C | 19 |
2 files changed, 21 insertions, 0 deletions
diff --git a/gcc/cp/cvt.cc b/gcc/cp/cvt.cc index db086c0..d95e01c 100644 --- a/gcc/cp/cvt.cc +++ b/gcc/cp/cvt.cc @@ -1664,6 +1664,8 @@ convert_to_void (tree expr, impl_conv_void implicit, tsubst_flags_t complain) if (tclass == tcc_comparison || tclass == tcc_unary || tclass == tcc_binary + || code == TRUTH_NOT_EXPR + || code == ADDR_EXPR || code == VEC_PERM_EXPR || code == VEC_COND_EXPR) warn_if_unused_value (e, loc); diff --git a/gcc/testsuite/g++.dg/warn/Wunused-20.C b/gcc/testsuite/g++.dg/warn/Wunused-20.C new file mode 100644 index 0000000..31b1920 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wunused-20.C @@ -0,0 +1,19 @@ +// PR c++/114104 +// { dg-additional-options "-Wunused-value" } + +bool f(); +struct A { int i; }; +A& g(); + +void h() { + !f(); // { dg-warning "value computed is not used" } + &g().i; // { dg-warning "value computed is not used" } +} + +#if __cplusplus >= 202002L +[[nodiscard]] bool operator==(A&, int); + +void h(A a) { + a != 0; // { dg-warning "value computed is not used" "" { target c++20 } } +} +#endif |