27a972a699
(This relands 59337263ab45d7657e and makes sure comma operator diagnostics are suppressed in a SFINAE context.) While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator. This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96) Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D103938
52 lines
1.8 KiB
C++
52 lines
1.8 KiB
C++
// RUN: %clang_cc1 -std=c++1z -verify %s -Wno-vexing-parse
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int g, h;
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typedef int T;
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int f() {
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// init-statement declarations
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if (T n = 0; n != 0) {}
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if (T f(); f()) {}
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if (T(f()); f()) {}
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if (T(f()), g, h; f()) {}
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if (T f(); f()) {}
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if (T f(), g, h; f()) {}
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if (T(n) = 0; n) {}
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// init-statement expressions
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if (T{f()}; f()) {} // expected-warning {{expression result unused}}
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if (T{f()}, g, h; f()) {} // expected-warning 2{{left operand of comma operator has no effect}} expected-warning {{expression result unused}}
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if (T(f()), g, h + 1; f()) {} // expected-warning 2{{left operand of comma operator has no effect}} expected-warning {{expression result unused}}
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// condition declarations
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if (T(n){g}) {}
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if (T f()) {} // expected-error {{function type}}
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if (T f(), g, h) {} // expected-error {{function type}}
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if (T(n) = 0) {}
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// condition expressions
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if (T(f())) {}
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if (T{f()}) {}
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if (T(f()), g, h) {} // expected-warning 2{{left operand of comma operator has no effect}}
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if (T{f()}, g, h) {} // expected-warning 2{{left operand of comma operator has no effect}}
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// none of the above, disambiguated as expression (can't be a declaration)
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if (T(n)(g)) {} // expected-error {{undeclared identifier 'n'}}
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if (T(n)(int())) {} // expected-error {{undeclared identifier 'n'}}
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// Likewise for 'switch'
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switch (int n; n) {}
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switch (g; int g = 5) {} // expected-warning {{expression result unused}}
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if (int a, b; int c = a) { // expected-note 6{{previous}}
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int a; // expected-error {{redefinition}}
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int b; // expected-error {{redefinition}}
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int c; // expected-error {{redefinition}}
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} else {
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int a; // expected-error {{redefinition}}
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int b; // expected-error {{redefinition}}
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int c; // expected-error {{redefinition}}
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}
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return 0;
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}
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