c: Fix bogus vector initialisation error [PR96377]
One of the problems in this PR was that if we had:
vector_type1 array[] = { vector_value1 };
process_init_element would only treat vector_value1 as initialising
a vector_type1 if they had the same TYPE_MAIN_VARIANT. This has
several problems:
(1) It gives confusing error messages if the vector types are
incompatible. (Tested by gcc.dg/pr96377-1.c.)
(2) It means that we reject code that should be valid with
-flax-vector-conversions. (Tested by gcc.dg/pr96377-2.c.)
(3) On arm and aarch64 targets, it means that we reject some
initializers that mix Advanced SIMD and standard GNU vectors.
These vectors have traditionally had different TYPE_MAIN_VARIANTs
because they have different mangling schemes. (Tested by
gcc.dg/pr96377-[3-6].c.)
(4) It means that we reject SVE initializers that should be valid.
(Tested by gcc.target/aarch64/sve/gnu_vectors_[34].c.)
(5) After r11-1741-g:
31427b974ed7b7dd54e2 we reject:
arm_neon_type1 array[] = { k ^ arm_neon_value1 };
because applying the binary operator to arm_neon_value1 strips
the "Advanced SIMD type" attributes that were added in that patch.
Stripping the attributes is problematic for other reasons though,
so that still needs to be fixed separately.
g++.target/aarch64/sve/gnu_vectors_[34].C already pass.
gcc/c/
PR c/96377
* c-typeck.c (process_init_element): Split test for whether to
recurse into a record, union or array into...
(initialize_elementwise_p): ...this new function. Don't recurse
into a vector type if the initialization value is also a vector.
gcc/testsuite/
PR c/96377
* gcc.dg/pr96377-1.c: New test.
* gcc.dg/pr96377-2.c: Likewise.
* gcc.dg/pr96377-3.c: Likewise.
* gcc.dg/pr96377-4.c: Likewise.
* gcc.dg/pr96377-5.c: Likewise.
* gcc.dg/pr96377-6.c: Likewise.
* gcc.target/aarch64/pr96377-1.c: Likewise.
* gcc.target/aarch64/sve/acle/general-c/gnu_vectors_3.c: Likewise.
* gcc.target/aarch64/sve/acle/general-c/gnu_vectors_4.c: Likewise.
* g++.target/aarch64/sve/acle/general-c++/gnu_vectors_3.C: Likewise.
* g++.target/aarch64/sve/acle/general-c++/gnu_vectors_4.C: Likewise.