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| author | Jason Merrill <jason@redhat.com> | 2025-03-19 05:15:00 -0400 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2025-03-19 17:58:23 -0400 |
| commit | 80e1dac3849b134ebd5e0151e9c9e4b8b091de72 (patch) | |
| tree | 37343b646cff006767d99761f6905ad26a919d62 | |
| parent | e3b3290f7330a81176d3d5d7c77623cd6c4bc70c (diff) | |
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c++: mangling of array new [PR119316]
Because we build an array type to represent an array new, we hit a VLA
error in compute_array_index_type for a variable length array new. To avoid
this, let's build the MINUS_EXPR and index type directly.
I also noticed that the non-constant case in write_array_type was assuming
MINUS_EXPR without verifying it, so I added a checking_assert.
I also noticed that Clang doesn't mangle the length of an array new at all,
so I opened https://github.com/itanium-cxx-abi/cxx-abi/issues/199 to clarify
this.
PR c++/119316
gcc/cp/ChangeLog:
* mangle.cc (write_expression) [NEW_EXPR]: Avoid using
compute_array_index_type.
(write_array_type): Add checking_assert.
gcc/testsuite/ChangeLog:
* g++.dg/abi/mangle-new1.C: New test.
| -rw-r--r-- | gcc/cp/mangle.cc | 13 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/abi/mangle-new1.C | 10 |
2 files changed, 20 insertions, 3 deletions
diff --git a/gcc/cp/mangle.cc b/gcc/cp/mangle.cc index df61f2d..9ca5cf6 100644 --- a/gcc/cp/mangle.cc +++ b/gcc/cp/mangle.cc @@ -3642,10 +3642,15 @@ write_expression (tree expr) if (nelts) { - tree domain; ++processing_template_decl; - domain = compute_array_index_type (NULL_TREE, nelts, - tf_warning_or_error); + /* Avoid compute_array_index_type complaints about + non-constant nelts. */ + tree max = cp_build_binary_op (input_location, MINUS_EXPR, + fold_convert (sizetype, nelts), + size_one_node, + tf_warning_or_error); + max = maybe_constant_value (max); + tree domain = build_index_type (max); type = build_cplus_array_type (type, domain); --processing_template_decl; } @@ -4242,6 +4247,8 @@ write_array_type (const tree type) } else { + gcc_checking_assert (TREE_CODE (max) == MINUS_EXPR + && integer_onep (TREE_OPERAND (max, 1))); max = TREE_OPERAND (max, 0); write_expression (max); } diff --git a/gcc/testsuite/g++.dg/abi/mangle-new1.C b/gcc/testsuite/g++.dg/abi/mangle-new1.C new file mode 100644 index 0000000..bb3ea9b --- /dev/null +++ b/gcc/testsuite/g++.dg/abi/mangle-new1.C @@ -0,0 +1,10 @@ +// PR c++/119316 +// { dg-do compile { target c++11 } } + +template <unsigned> struct A { }; +template<typename T> +auto foo(unsigned n) -> A<sizeof(new T[n])> +{ return {}; } +int main() { foo<int>(5); } + +// { dg-final { scan-assembler {_Z3fooIiE1AIXszna_Afp__T_EEEj} } } |