| 1 | // RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify -Wc++17-extensions %s |
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| 2 | // RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT -Wc++17-extensions %s |
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| 3 | |
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| 4 | struct [[nodiscard]] S {}; |
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| 5 | S get_s(); |
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| 6 | S& get_s_ref(); |
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| 7 | |
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| 8 | enum [[nodiscard]] E {}; |
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| 9 | E get_e(); |
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| 10 | |
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| 11 | [[nodiscard]] int get_i(); |
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| 12 | [[nodiscard]] volatile int &get_vi(); |
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| 13 | |
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| 14 | void f() { |
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| 15 | get_s(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 16 | get_i(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 17 | get_vi(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 18 | get_e(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 19 | |
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| 20 | // Okay, warnings are not encouraged |
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| 21 | get_s_ref(); |
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| 22 | (void)get_s(); |
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| 23 | (void)get_i(); |
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| 24 | (void)get_vi(); |
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| 25 | (void)get_e(); |
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| 26 | } |
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| 27 | |
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| 28 | [[nodiscard]] volatile char &(*fp)(); |
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| 29 | void g() { |
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| 30 | fp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 31 | |
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| 32 | // OK, warning suppressed. |
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| 33 | (void)fp(); |
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| 34 | } |
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| 35 | |
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| 36 | namespace PR31526 { |
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| 37 | typedef E (*fp1)(); |
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| 38 | typedef S (*fp2)(); |
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| 39 | |
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| 40 | typedef S S_alias; |
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| 41 | typedef S_alias (*fp3)(); |
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| 42 | |
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| 43 | typedef fp2 fp2_alias; |
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| 44 | |
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| 45 | void f() { |
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| 46 | fp1 one; |
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| 47 | fp2 two; |
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| 48 | fp3 three; |
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| 49 | fp2_alias four; |
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| 50 | |
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| 51 | one(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 52 | two(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 53 | three(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 54 | four(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} |
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| 55 | |
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| 56 | // These are all okay because of the explicit cast to void. |
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| 57 | (void)one(); |
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| 58 | (void)two(); |
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| 59 | (void)three(); |
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| 60 | (void)four(); |
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| 61 | } |
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| 62 | } // namespace PR31526 |
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| 63 | |
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| 64 | #ifdef EXT |
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| 65 | // expected-warning@4 {{use of the 'nodiscard' attribute is a C++17 extension}} |
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| 66 | // expected-warning@8 {{use of the 'nodiscard' attribute is a C++17 extension}} |
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| 67 | // expected-warning@11 {{use of the 'nodiscard' attribute is a C++17 extension}} |
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| 68 | // expected-warning@12 {{use of the 'nodiscard' attribute is a C++17 extension}} |
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| 69 | // expected-warning@28 {{use of the 'nodiscard' attribute is a C++17 extension}} |
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| 70 | #endif |
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| 71 | |
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