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This commit introduces a new attribute `called_once`. It can be applied to function-like parameters to signify that this parameter should be called exactly once. This concept is particularly widespread in asynchronous programs. Additionally, this commit introduce a new group of dataflow analysis-based warnings to check this property. It identifies and reports the following situations: * parameter is called twice * parameter is never called * parameter is not called on one of the paths Current implementation can also automatically infer `called_once` attribute for completion handler paramaters that should follow the same principle by convention. This behavior is OFF by default and can be turned on by using `-Wcompletion-handler`. Differential Revision: https://reviews.llvm.org/D92039 rdar://72812043
21 lines
958 B
Objective-C
21 lines
958 B
Objective-C
// RUN: %clang_cc1 -verify -fsyntax-only -fobjc-arc -fblocks %s
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#define CALLED_ONCE __attribute__((called_once))
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void test1(int x CALLED_ONCE); // expected-error{{'called_once' attribute only applies to function-like parameters}}
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void test2(double x CALLED_ONCE); // expected-error{{'called_once' attribute only applies to function-like parameters}}
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void test3(void (*foo)() CALLED_ONCE); // no-error
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void test4(int (^foo)(int) CALLED_ONCE); // no-error
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void test5(void (*foo)() __attribute__((called_once(1))));
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// expected-error@-1{{'called_once' attribute takes no arguments}}
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void test6(void (*foo)() __attribute__((called_once("str1", "str2"))));
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// expected-error@-1{{'called_once' attribute takes no arguments}}
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CALLED_ONCE void test7(); // expected-warning{{'called_once' attribute only applies to parameters}}
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void test8() {
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void (*foo)() CALLED_ONCE; // expected-warning{{'called_once' attribute only applies to parameters}}
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foo();
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}
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