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| author | Marek Polacek <polacek@redhat.com> | 2021-07-07 20:02:18 -0400 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2021-07-08 17:38:49 -0400 |
| commit | dee00bf6894be0cabb8f263c993357a6f8444f8b (patch) | |
| tree | 28900c25657b1c8193f3d6491c7b58a5c57806b2 | |
| parent | b14ac7b29c9a05c94f62fe065c219bbaa83653db (diff) | |
| download | gcc-dee00bf6894be0cabb8f263c993357a6f8444f8b.zip gcc-dee00bf6894be0cabb8f263c993357a6f8444f8b.tar.gz gcc-dee00bf6894be0cabb8f263c993357a6f8444f8b.tar.bz2 | |
c++: Fix noexcept with unevaluated operand [PR101087]
It sounds plausible that this assert
int f();
static_assert(noexcept(sizeof(f())));
should pass: sizeof produces a std::size_t and its operand is not
evaluated, so it can't throw. noexcept should only evaluate to
false for potentially evaluated operands. Therefore I think that
check_noexcept_r shouldn't walk into operands of sizeof/decltype/
alignof/typeof.
PR c++/101087
gcc/cp/ChangeLog:
* cp-tree.h (unevaluated_p): New.
* except.c (check_noexcept_r): Use it. Don't walk into
unevaluated operands.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept70.C: New test.
| -rw-r--r-- | gcc/cp/cp-tree.h | 13 | ||||
| -rw-r--r-- | gcc/cp/except.c | 9 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp0x/noexcept70.C | 5 |
3 files changed, 24 insertions, 3 deletions
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index b450157..d4810c0 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -8465,6 +8465,19 @@ is_constrained_auto (const_tree t) return is_auto (t) && PLACEHOLDER_TYPE_CONSTRAINTS_INFO (t); } +/* True if CODE, a tree code, denotes a tree whose operand is not evaluated + as per [expr.context], i.e., an operand to sizeof, typeof, decltype, or + alignof. */ + +inline bool +unevaluated_p (tree_code code) +{ + return (code == DECLTYPE_TYPE + || code == ALIGNOF_EXPR + || code == SIZEOF_EXPR + || code == NOEXCEPT_EXPR); +} + /* RAII class to push/pop the access scope for T. */ struct push_access_scope_guard diff --git a/gcc/cp/except.c b/gcc/cp/except.c index a8cea53..a8acbc4 100644 --- a/gcc/cp/except.c +++ b/gcc/cp/except.c @@ -1033,12 +1033,15 @@ check_handlers (tree handlers) expression whose type is a polymorphic class type (10.3). */ static tree -check_noexcept_r (tree *tp, int * /*walk_subtrees*/, void * /*data*/) +check_noexcept_r (tree *tp, int *walk_subtrees, void *) { tree t = *tp; enum tree_code code = TREE_CODE (t); - if ((code == CALL_EXPR && CALL_EXPR_FN (t)) - || code == AGGR_INIT_EXPR) + + if (unevaluated_p (code)) + *walk_subtrees = false; + else if ((code == CALL_EXPR && CALL_EXPR_FN (t)) + || code == AGGR_INIT_EXPR) { /* We can only use the exception specification of the called function for determining the value of a noexcept expression; we can't use diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept70.C b/gcc/testsuite/g++.dg/cpp0x/noexcept70.C new file mode 100644 index 0000000..45a6137 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept70.C @@ -0,0 +1,5 @@ +// PR c++/101087 +// { dg-do compile { target c++11 } } + +int f(); +static_assert(noexcept(sizeof(f())), ""); |