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| author | Marek Polacek <polacek@redhat.com> | 2024-04-01 12:55:46 -0400 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2024-04-02 14:32:29 -0400 |
| commit | 2f2924078ce51c2a0da3ad8f958f2d1de533969a (patch) | |
| tree | fec546799ef7887d73086b3eba1bd9cac80f7c78 /gcc | |
| parent | daa2e7c7ffe49b788357f7f2c9ef1c9b125c1f8c (diff) | |
| download | gcc-2f2924078ce51c2a0da3ad8f958f2d1de533969a.zip gcc-2f2924078ce51c2a0da3ad8f958f2d1de533969a.tar.gz gcc-2f2924078ce51c2a0da3ad8f958f2d1de533969a.tar.bz2 | |
c++: make __is_array return false for T[0] [PR114479]
When we switched to using the __is_array built-in trait to implement
std::is_array in r14-6623-g7fd9c349e45534, we started saying that
T[0] is an array. There are various opinions as to whether that is
the best answer, but it seems prudent to keep the GCC 13 result.
PR c++/114479
gcc/cp/ChangeLog:
* semantics.cc (trait_expr_value) <case CPTK_IS_ARRAY>: Return false
for zero-sized arrays.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_array.C: Extend.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/semantics.cc | 8 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/ext/is_array.C | 12 |
2 files changed, 19 insertions, 1 deletions
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc index 9838331..0015ff4 100644 --- a/gcc/cp/semantics.cc +++ b/gcc/cp/semantics.cc @@ -12439,7 +12439,13 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2) return CP_AGGREGATE_TYPE_P (type1); case CPTK_IS_ARRAY: - return type_code1 == ARRAY_TYPE; + return (type_code1 == ARRAY_TYPE + /* We don't want to report T[0] as being an array type. + This is for compatibility with an implementation of + std::is_array by template argument deduction, because + compute_array_index_type_loc rejects a zero-size array + in SFINAE context. */ + && !(TYPE_SIZE (type1) && integer_zerop (TYPE_SIZE (type1)))); case CPTK_IS_ASSIGNABLE: return is_xible (MODIFY_EXPR, type1, type2); diff --git a/gcc/testsuite/g++.dg/ext/is_array.C b/gcc/testsuite/g++.dg/ext/is_array.C index f1a6e08..8499326 100644 --- a/gcc/testsuite/g++.dg/ext/is_array.C +++ b/gcc/testsuite/g++.dg/ext/is_array.C @@ -1,4 +1,5 @@ // { dg-do compile { target c++11 } } +// { dg-options "" } #define SA(X) static_assert((X),#X) @@ -10,18 +11,29 @@ class ClassType { }; +constexpr int sz0 = 0; +constexpr int sz2 = 2; + SA_TEST_CATEGORY(__is_array, int[2], true); SA_TEST_CATEGORY(__is_array, int[], true); +SA_TEST_CATEGORY(__is_array, int[0], false); SA_TEST_CATEGORY(__is_array, int[2][3], true); SA_TEST_CATEGORY(__is_array, int[][3], true); +SA_TEST_CATEGORY(__is_array, int[0][3], false); +SA_TEST_CATEGORY(__is_array, int[3][0], false); SA_TEST_CATEGORY(__is_array, float*[2], true); SA_TEST_CATEGORY(__is_array, float*[], true); SA_TEST_CATEGORY(__is_array, float*[2][3], true); SA_TEST_CATEGORY(__is_array, float*[][3], true); SA_TEST_CATEGORY(__is_array, ClassType[2], true); SA_TEST_CATEGORY(__is_array, ClassType[], true); +SA_TEST_CATEGORY(__is_array, ClassType[0], false); SA_TEST_CATEGORY(__is_array, ClassType[2][3], true); SA_TEST_CATEGORY(__is_array, ClassType[][3], true); +SA_TEST_CATEGORY(__is_array, ClassType[0][3], false); +SA_TEST_CATEGORY(__is_array, ClassType[2][0], false); +SA_TEST_CATEGORY(__is_array, int[sz2], true); +SA_TEST_CATEGORY(__is_array, int[sz0], false); // Sanity check. SA_TEST_CATEGORY(__is_array, ClassType, false); |