为啥C++模板特化在g++编译错误但是clang++成功编译？

Question

class Widget {public:    template<typename T>    void processPointer(T* ptr)    { }private:    template<>    void processPointer<void>(void*);};int main(){    Widget w;    w.processPointer(new int());    return 0;}

补充clang++编译后的汇编代码：

    .text    .file    "private.cpp"    .globl    main                            # -- Begin function main    .p2align    4, 0x90    .type    main,@functionmain:                                   # @main    .cfi_startproc# %bb.0:    pushq    %rbp    .cfi_def_cfa_offset 16    .cfi_offset %rbp, -16    movq    %rsp, %rbp    .cfi_def_cfa_register %rbp    subq    $16, %rsp    movl    $0, -4(%rbp)    movl    $4, %edi    callq    _Znwm@PLT    movq    %rax, %rsi    movl    $0, (%rax)    leaq    -8(%rbp), %rdi    callq    _ZN6Widget14processPointerIiEEvPT_    xorl    %eax, %eax    addq    $16, %rsp    popq    %rbp    .cfi_def_cfa %rsp, 8    retq.Lfunc_end0:    .size    main, .Lfunc_end0-main    .cfi_endproc                                        # -- End function    .section    .text._ZN6Widget14processPointerIiEEvPT_,"axG",@progbits,_ZN6Widget14processPointerIiEEvPT_,comdat    .weak    _ZN6Widget14processPointerIiEEvPT_ # -- Begin function _ZN6Widget14processPointerIiEEvPT_    .p2align    4, 0x90    .type    _ZN6Widget14processPointerIiEEvPT_,@function_ZN6Widget14processPointerIiEEvPT_:     # @_ZN6Widget14processPointerIiEEvPT_    .cfi_startproc# %bb.0:    pushq    %rbp    .cfi_def_cfa_offset 16    .cfi_offset %rbp, -16    movq    %rsp, %rbp    .cfi_def_cfa_register %rbp    movq    %rdi, -8(%rbp)    movq    %rsi, -16(%rbp)    popq    %rbp    .cfi_def_cfa %rsp, 8    retq.Lfunc_end1:    .size    _ZN6Widget14processPointerIiEEvPT_, .Lfunc_end1-_ZN6Widget14processPointerIiEEvPT_    .cfi_endproc                                        # -- End function    .ident    "Ubuntu clang version 14.0.0-1ubuntu1.1"    .section    ".note.GNU-stack","",@progbits    .addrsig    .addrsig_sym _ZN6Widget14processPointerIiEEvPT_    .addrsig_sym _Znwm

编译结果：

Answer 1

gcc 的 bug。

c++17 开始标准决定支持在类里特化，然后就有了这个 bug report ，但是现在都还没有修复。