5030928d60
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
50 lines
2.5 KiB
C
50 lines
2.5 KiB
C
// RUN: %clang_cc1 -std=c11 -fsyntax-only -verify %s
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// RUN: %clang_cc1 -std=c99 -pedantic -fsyntax-only -verify=expected,ext %s
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// RUN: %clang_cc1 -xc++ -std=c++11 -pedantic -fsyntax-only -verify=expected,ext,cxx %s
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_Static_assert("foo", "string is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
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#ifndef __cplusplus
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// expected-error@-2 {{static_assert expression is not an integral constant expression}}
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#endif
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_Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
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_Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
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// ext-warning {{'_Static_assert' is a C11 extension}}
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void foo(void) {
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_Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
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_Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
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// ext-warning {{'_Static_assert' is a C11 extension}}
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}
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_Static_assert(1, invalid); // expected-error {{expected string literal for diagnostic message in static_assert}} \
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// ext-warning {{'_Static_assert' is a C11 extension}}
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struct A {
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int a;
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_Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
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_Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
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// ext-warning {{'_Static_assert' is a C11 extension}}
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};
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#ifdef __cplusplus
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#define ASSERT_IS_TYPE(T) __is_same(T, T)
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#else
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#define ASSERT_IS_TYPE(T) __builtin_types_compatible_p(T, T)
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#endif
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#define UNION(T1, T2) union { \
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__typeof__(T1) one; \
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__typeof__(T2) two; \
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_Static_assert(ASSERT_IS_TYPE(T1), "T1 is not a type"); \
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_Static_assert(ASSERT_IS_TYPE(T2), "T2 is not a type"); \
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_Static_assert(sizeof(T1) == sizeof(T2), "type size mismatch"); \
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}
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typedef UNION(unsigned, struct A) U1; // ext-warning 3 {{'_Static_assert' is a C11 extension}}
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UNION(char[2], short) u2 = { .one = { 'a', 'b' } }; // ext-warning 3 {{'_Static_assert' is a C11 extension}} cxx-warning {{designated initializers are a C++20 extension}}
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typedef UNION(char, short) U3; // expected-error {{static_assert failed due to requirement 'sizeof(char) == sizeof(short)' "type size mismatch"}} \
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// ext-warning 3 {{'_Static_assert' is a C11 extension}}
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typedef UNION(float, 0.5f) U4; // expected-error {{expected a type}} \
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// ext-warning 3 {{'_Static_assert' is a C11 extension}}
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