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问题 Code example: struct A {}; struct B { using A = A; }; int main() { B b; } Clang compiles it. But GCC gives the following error (demo): declaration of 'using A = struct A' changes meaning of 'A' The C++ standard says: If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name ( excluding declarations made visible via using-directives ([basic.lookup.unqual])),

问题 Code example: struct A {}; struct B { using A = A; }; int main() { B b; } Clang compiles it. But GCC gives the following error (demo): declaration of 'using A = struct A' changes meaning of 'A' The C++ standard says: If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name ( excluding declarations made visible via using-directives ([basic.lookup.unqual])),

问题 Code example: struct A {}; struct B { using A = A; }; int main() { B b; } Clang compiles it. But GCC gives the following error (demo): declaration of 'using A = struct A' changes meaning of 'A' The C++ standard says: If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name ( excluding declarations made visible via using-directives ([basic.lookup.unqual])),

问题 Code example: struct A {}; struct B { using A = A; }; int main() { B b; } Clang compiles it. But GCC gives the following error (demo): declaration of 'using A = struct A' changes meaning of 'A' The C++ standard says: If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name ( excluding declarations made visible via using-directives ([basic.lookup.unqual])),

问题 Code example: struct A {}; struct B { using A = A; }; int main() { B b; } Clang compiles it. But GCC gives the following error (demo): declaration of 'using A = struct A' changes meaning of 'A' The C++ standard says: If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name ( excluding declarations made visible via using-directives ([basic.lookup.unqual])),

问题 This question already has answers here : Writing to a signed integer as if it is unsigned in C++ (2 answers) Efficient way to bit-copy a signed integer to an unsigned integer (4 answers) Closed 3 years ago . Compiler generates code assuming that an int can be aliased by an unsigned int . The folowing code: int f(int& a, unsigned int& b){ a=10; b=12; return a; } int f(int& a, double& b){ a=10; b=12; return a; } generates the folowing assembly, using Clang5 (similar code is produced by GCC or

问题 This question already has answers here : Writing to a signed integer as if it is unsigned in C++ (2 answers) Efficient way to bit-copy a signed integer to an unsigned integer (4 answers) Closed 3 years ago . Compiler generates code assuming that an int can be aliased by an unsigned int . The folowing code: int f(int& a, unsigned int& b){ a=10; b=12; return a; } int f(int& a, double& b){ a=10; b=12; return a; } generates the folowing assembly, using Clang5 (similar code is produced by GCC or

问题 This question already has answers here : Writing to a signed integer as if it is unsigned in C++ (2 answers) Efficient way to bit-copy a signed integer to an unsigned integer (4 answers) Closed 3 years ago . Compiler generates code assuming that an int can be aliased by an unsigned int . The folowing code: int f(int& a, unsigned int& b){ a=10; b=12; return a; } int f(int& a, double& b){ a=10; b=12; return a; } generates the folowing assembly, using Clang5 (similar code is produced by GCC or

问题 This question already has answers here : Writing to a signed integer as if it is unsigned in C++ (2 answers) Efficient way to bit-copy a signed integer to an unsigned integer (4 answers) Closed 3 years ago . Compiler generates code assuming that an int can be aliased by an unsigned int . The folowing code: int f(int& a, unsigned int& b){ a=10; b=12; return a; } int f(int& a, double& b){ a=10; b=12; return a; } generates the folowing assembly, using Clang5 (similar code is produced by GCC or

问题 (This question has been broken out from the discussion to this answer, which highlights CWG 1892) Some paragraphs of the standard applies specific rules to function declarators ; e.g. [dcl.spec.auto]/3 regarding placeholder types [ emphasis mine]: The placeholder type can appear with a function declarator in the decl-specifier-seq , type-specifier-seq , conversion-function-id , or trailing-return-type , in any context where such a declarator is valid. If the function declarator includes a