09117b2189
For failed static assertions, try to take the expression apart and print useful information about why it failed. In particular, look at binary operators and print the compile-time evaluated value of the LHS/RHS. Differential Revision: https://reviews.llvm.org/D130894
50 lines
1.8 KiB
C++
50 lines
1.8 KiB
C++
// RUN: %clang_cc1 -std=c++2a -verify %s
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namespace p3 {
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void bar(...);
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template <typename... Args> void foo(Args... args) {
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(void)[... xs = args] {
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bar(xs...);
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};
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}
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void use() {
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foo();
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foo(1);
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}
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}
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template<typename ...T> void f(T ...t) {
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(void)[&...x = t] {
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x; // expected-error {{unexpanded parameter pack 'x'}}
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};
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// Not OK: can't expand 'x' outside its scope.
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weird((void)[&...x = t] {
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return &x; // expected-error {{unexpanded parameter pack 'x'}}
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}... // expected-error {{does not contain any unexpanded}}
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);
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// OK, capture only one 'slice' of 'x'.
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weird((void)[&x = t] {
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return &x;
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}...
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);
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// 'x' is not expanded by the outer '...', but 'T' is.
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weird((void)[&... x = t] {
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return T() + &x; // expected-error {{unexpanded parameter pack 'x'}}
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}... // expected-error {{does not contain any unexpanded}}
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);
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}
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template<int ...a> constexpr auto x = [...z = a] (auto F) { return F(z...); };
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static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 123);
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static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
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// expected-note {{evaluates to '123 == 124'}}
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template<int ...a> constexpr auto y = [z = a...] (auto F) { return F(z...); }; // expected-error {{must appear before the name of the capture}}
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static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 123);
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static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
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// expected-note {{evaluates to '123 == 124'}}
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