llvm-project/clang/test/SemaCXX/designated-initializers-bas...

// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -Winitializer-overrides

struct B {
  int x;
};

struct D : B {
  int y;
};

void test() { D d = {1, .y = 2}; } // expected-warning {{C99 extension}} expected-note {{}}
[Sema] Fix bug in handling of designated initializer. CheckDesignatedInitializer wasn't taking into account the base classes when computing the index for the field in the derived class, which caused the test case to crash during IRGen because of a malformed AST. rdar://problem/26795040 Differential Revision: https://reviews.llvm.org/D28705 llvm-svn: 292245 2017-01-18 03:35:54 +08:00			`// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -Winitializer-overrides`

			`struct B {`
			`int x;`
			`};`

			`struct D : B {`
			`int y;`
			`};`

[c++20] Implement semantic restrictions for C++20 designated initializers. This has some interesting interactions with our existing extensions to support C99 designated initializers as an extension in C++. Those are resolved as follows: * We continue to permit the full breadth of C99 designated initializers in C++, with the exception that we disallow a partial overwrite of an initializer with a non-trivially-destructible type. (Full overwrite is OK, because we won't run the first initializer at all.) * The C99 extensions are disallowed in SFINAE contexts and during overload resolution, where they could change the meaning of valid programs. * C++20 disallows reordering of initializers. We only check for that for the simple cases that the C++20 rules permit (designators of the form '.field_name =' and continue to allow reordering in other cases). It would be nice to improve this behavior in future. * All C99 designated initializer extensions produce a warning by default in C++20 mode. People are going to learn the C++ rules based on what Clang diagnoses, so it's important we diagnose these properly by default. * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and so still diagnose C99 extensions as described above. We continue to accept designated C++20-compatible initializers in C++ <= 17 silently by default (but naturally still reject under -pedantic-errors). This is not a complete implementation of P0329R4. In particular, that paper introduces new non-C99-compatible syntax { .field { init } }, and we do not support that yet. This is based on a previous patch by Don Hinton, though I've made substantial changes when addressing the above interactions. Differential Revision: https://reviews.llvm.org/D59754 llvm-svn: 370544 2019-08-31 06:52:55 +08:00			`void test() { D d = {1, .y = 2}; } // expected-warning {{C99 extension}} expected-note {{}}`