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Should consteval constructor produce symbols? #82154

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ChuanqiXu9 opened this issue Feb 18, 2024 · 3 comments · Fixed by #82179
Closed

Should consteval constructor produce symbols? #82154

ChuanqiXu9 opened this issue Feb 18, 2024 · 3 comments · Fixed by #82179
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c++20 clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party consteval C++20 consteval

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@ChuanqiXu9
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(From #81745)

During the debugging process, I found the codegen will generate consteval constructor. It is surprising to me. In my memory, we shouldn't emit consteval functions at all.

Reproducer:

// test-main.cc
struct S1 { consteval S1(int) {} };
int main() {
    struct S2 { S1 s = 0; };
    S2 s;
}

$ clang++ -std=c++20 test-main.cc -c -o main.o
$nm -C main.o | grep S1
0000000000000000 W S1::S1(int)

We can double check the LLVM IR:

$ clang++ -std=c++20 test-main.cc -fmodule-file=M=test.pcm -S -emit-llvm -o -

We should be able to see the definition of @_ZN2S1C2Ei. And we can demangle it by:

$ llvm-cxxfilt _ZN2S1C2Ei
S1::S1(int)
@ChuanqiXu9 ChuanqiXu9 added c++20 consteval C++20 consteval labels Feb 18, 2024
@llvmbot
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llvmbot commented Feb 18, 2024

@llvm/issue-subscribers-c-20

Author: Chuanqi Xu (ChuanqiXu9)

(From https://github.com//issues/81745)

During the debugging process, I found the codegen will generate consteval constructor. It is surprising to me. In my memory, we shouldn't emit consteval functions at all.

Reproducer:

// test-main.cc
struct S1 { consteval S1(int) {} };
int main() {
    struct S2 { S1 s = 0; };
    S2 s;
}

$ clang++ -std=c++20 test-main.cc -c -o main.o
$nm -C main.o | grep S1
0000000000000000 W S1::S1(int)

We can double check the LLVM IR:

$ clang++ -std=c++20 test-main.cc -fmodule-file=M=test.pcm -S -emit-llvm -o -

We should be able to see the definition of @<!-- -->_ZN2S1C2Ei. And we can demangle it by:

$ llvm-cxxfilt _ZN2S1C2Ei
S1::S1(int)

@ChuanqiXu9 ChuanqiXu9 mentioned this issue Feb 18, 2024
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@ChuanqiXu9
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CC: @erichkeane @cor3ntin @tbaederr

@cor3ntin cor3ntin added the confirmed Verified by a second party label Feb 18, 2024
cor3ntin added a commit to cor3ntin/llvm-project that referenced this issue Feb 18, 2024
@cor3ntin
[Clang] CXXConstructExpr may be immediate calls.
c44bc36 
A CXXConstructExpr may refer to an immediate constructor,
in which case it should be substituted in the
enclosing default init expression.

Fixes llvm#82154
@cor3ntin cor3ntin mentioned this issue Feb 18, 2024
Merged
cor3ntin added a commit that referenced this issue Feb 19, 2024
@cor3ntin
[Clang] CXXConstructExpr may be immediate calls. (#82179)
9d3d6ec 
A CXXConstructExpr may refer to an immediate constructor, in which case
it should be substituted in the
enclosing default init expression.

Fixes #82154
@EugeneZelenko EugeneZelenko added the clang:frontend Language frontend issues, e.g. anything involving "Sema" label Feb 19, 2024
@llvmbot
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llvmbot commented Feb 19, 2024

@llvm/issue-subscribers-clang-frontend

Author: Chuanqi Xu (ChuanqiXu9)

(From https://github.com//issues/81745)

During the debugging process, I found the codegen will generate consteval constructor. It is surprising to me. In my memory, we shouldn't emit consteval functions at all.

Reproducer:

// test-main.cc
struct S1 { consteval S1(int) {} };
int main() {
    struct S2 { S1 s = 0; };
    S2 s;
}

$ clang++ -std=c++20 test-main.cc -c -o main.o
$nm -C main.o | grep S1
0000000000000000 W S1::S1(int)

We can double check the LLVM IR:

$ clang++ -std=c++20 test-main.cc -fmodule-file=M=test.pcm -S -emit-llvm -o -

We should be able to see the definition of @<!-- -->_ZN2S1C2Ei. And we can demangle it by:

$ llvm-cxxfilt _ZN2S1C2Ei
S1::S1(int)

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c++20 clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party consteval C++20 consteval
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[Clang] CXXConstructExpr may be immediate calls. cor3ntin/llvm-project
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@cor3ntin @EugeneZelenko @llvmbot @ChuanqiXu9