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| author | Patrick Palka <ppalka@redhat.com> | 2020-03-13 14:30:39 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2020-03-23 16:08:43 -0400 |
| commit | 1f6c1c82eb5001a844b5ac535f6aba4a3257031f (patch) | |
| tree | da497ce06d4a5d8684da11fe5456b78a14e5f1a8 /gcc | |
| parent | ca6c722561ce9b9dc7b59cfd9d29c9b466732721 (diff) | |
| download | gcc-1f6c1c82eb5001a844b5ac535f6aba4a3257031f.zip gcc-1f6c1c82eb5001a844b5ac535f6aba4a3257031f.tar.gz gcc-1f6c1c82eb5001a844b5ac535f6aba4a3257031f.tar.bz2 | |
c++: Avoid a suspicious -Wnoexcept warning [PR93805]
In this PR we're emitting -Wnoexcept warnings about potentially-throwing NSDMIs
when computing the noexcept specification of a class's defaulted default
constructor. Although these warnings are in some sense valid, this patch takes
the route of suppressing them, because:
1. the warning message is confusing in its current form;
2. warning for 'struct C { B b = B(); };' but not for 'struct C { B b; };'
is inconsistent; and
3. emitting a warning here arguably doesn't fall under the umbrella of
-Wnoexcept, whose documentation says it warns only when a
noexcept-expression evaluates to false, but there are no
noexcept-expressions here.
gcc/cp/ChangeLog:
PR c++/93805
* except.c (maybe_noexcept_warning): Add TODO comment.
* method.c (walk_field_subobs): Pass tf_none to expr_noexcept_p.
gcc/testsuite/ChangeLog:
PR c++/93805
* g++.dg/warn/Wnoexcept2.C: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/cp/except.c | 5 | ||||
| -rw-r--r-- | gcc/cp/method.c | 2 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/warn/Wnoexcept2.C | 15 |
5 files changed, 31 insertions, 2 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 3340f47..59db03c 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-03-23 Patrick Palka <ppalka@redhat.com> + + PR c++/93805 + * except.c (maybe_noexcept_warning): Add TODO. + * method.c (walk_field_subobs): Pass tf_none to expr_noexcept_p. + 2020-03-23 nathans <nathan@acm.org> PR c++/94044 diff --git a/gcc/cp/except.c b/gcc/cp/except.c index 262ba5d..7e93c51 100644 --- a/gcc/cp/except.c +++ b/gcc/cp/except.c @@ -1160,7 +1160,10 @@ struct GTY(()) pending_noexcept { static GTY(()) vec<pending_noexcept, va_gc> *pending_noexcept_checks; /* FN is a FUNCTION_DECL that caused a noexcept-expr to be false. Warn if - it can't throw. */ + it can't throw. + + TODO: Consider extending -Wnoexcept to do something like walk_subtrees in the + case of a defaulted function that obtained a noexcept(false) spec. */ static void maybe_noexcept_warning (tree fn) diff --git a/gcc/cp/method.c b/gcc/cp/method.c index c131fd4..41b9ff8 100644 --- a/gcc/cp/method.c +++ b/gcc/cp/method.c @@ -1988,7 +1988,7 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname, if (nsdmi == error_mark_node) *spec_p = error_mark_node; else if (*spec_p != error_mark_node - && !expr_noexcept_p (nsdmi, complain)) + && !expr_noexcept_p (nsdmi, tf_none)) *spec_p = noexcept_false_spec; } /* Don't do the normal processing. */ diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 1d053e0..5f079f1 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-03-23 Patrick Palka <ppalka@redhat.com> + + PR c++/93805 + * g++.dg/warn/Wnoexcept2.C: New test. + 2020-03-23 Jakub Jelinek <jakub@redhat.com> PR c++/91993 diff --git a/gcc/testsuite/g++.dg/warn/Wnoexcept2.C b/gcc/testsuite/g++.dg/warn/Wnoexcept2.C new file mode 100644 index 0000000..60541be --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wnoexcept2.C @@ -0,0 +1,15 @@ +// PR c++/93805 +// { dg-do compile { target c++11 } } +// { dg-additional-options "-Wnoexcept" } + +struct B +{ + B() {} +}; + +struct C +{ + B b = B(); +}; + +C c; // { dg-bogus "noexcept-expression" } |