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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
101 lines
2.8 KiB
C++
101 lines
2.8 KiB
C++
// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify %s
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// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify -std=c++98 %s
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// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify -std=c++11 %s
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// Test template instantiation for C99-specific features.
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// ---------------------------------------------------------------------
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// Designated initializers
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// ---------------------------------------------------------------------
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template<typename T, typename XType, typename YType>
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struct DesigInit0 {
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void f(XType x, YType y) {
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T agg = {
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#if __cplusplus <= 199711L
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.y = y, // expected-error{{does not refer}}
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.x = x // expected-error{{does not refer}}
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#else
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.y = static_cast<float>(y), // expected-error{{does not refer}}
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.x = static_cast<float>(x) // expected-error{{does not refer}}
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#endif
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};
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}
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};
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struct Point2D {
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float x, y;
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};
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template struct DesigInit0<Point2D, int, double>;
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struct Point3D {
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float x, y, z;
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};
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template struct DesigInit0<Point3D, int, double>;
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struct Color {
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unsigned char red, green, blue;
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};
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struct ColorPoint3D {
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Color color;
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float x, y, z;
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};
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template struct DesigInit0<ColorPoint3D, int, double>;
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template struct DesigInit0<Color, int, double>; // expected-note{{instantiation}}
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template<typename T, int Subscript1, int Subscript2,
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typename Val1, typename Val2>
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struct DesigArrayInit0 {
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void f(Val1 val1, Val2 val2) {
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T array = {
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#if __cplusplus <= 199711L
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[Subscript1] = val1,
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#else
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[Subscript1] = static_cast<int>(val1),
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#endif
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[Subscript2] = val2 // expected-error{{exceeds array bounds}}
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};
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int array2[10] = { [5] = 3 };
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}
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};
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template struct DesigArrayInit0<int[8], 5, 3, float, int>;
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template struct DesigArrayInit0<int[8], 5, 13, float, int>; // expected-note{{instantiation}}
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template<typename T, int Subscript1, int Subscript2,
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typename Val1>
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struct DesigArrayRangeInit0 {
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void f(Val1 val1) {
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T array = {
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#if __cplusplus <= 199711L
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[Subscript1...Subscript2] = val1 // expected-error{{exceeds}}
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#else
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[Subscript1...Subscript2] = static_cast<int>(val1) // expected-error{{exceeds}}
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#endif
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};
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}
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};
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template struct DesigArrayRangeInit0<int[8], 3, 5, float>;
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template struct DesigArrayRangeInit0<int[8], 5, 13, float>; // expected-note{{instantiation}}
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// ---------------------------------------------------------------------
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// Compound literals
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// ---------------------------------------------------------------------
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template<typename T, typename Arg1, typename Arg2>
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struct CompoundLiteral0 {
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T f(Arg1 a1, Arg2 a2) {
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#if __cplusplus <= 199711L
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return (T){a1, a2};
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#else
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return (T){static_cast<float>(a1), a2};
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#endif
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}
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};
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template struct CompoundLiteral0<Point2D, int, float>;
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