fix(libutil/posix-source-accessor.cc): get rid of use-after-move bug#11837
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Mic92 merged 1 commit intoNixOS:masterfrom Nov 8, 2024
xokdvium:dev/fix-use-after-move-posix-source
Merged
fix(libutil/posix-source-accessor.cc): get rid of use-after-move bug#11837Mic92 merged 1 commit intoNixOS:masterfrom xokdvium:dev/fix-use-after-move-posix-source
Mic92 merged 1 commit intoNixOS:masterfrom
xokdvium:dev/fix-use-after-move-posix-source
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Naming class member variables the same as constructor arguments is a very
slippery slope because of how member variable names get resolved. Compiler
is not very helpful here and we need static analysis to forbid this kind of
stuff.
The following example illustrates the cause quite well:
```cpp
struct B {
B(int) {}
};
struct A {
A(int b): b([&](){
return b;
static_assert(std::is_same_v<decltype(b), int>);
}()) {
static_assert(std::is_same_v<decltype(b), int>);
}
void member() {
static_assert(std::is_same_v<decltype(b), B>);
}
B b;
};
int main() {
A(1).member();
}
```
From N4861 6.5.1 Unqualified name lookup:
> In all the cases listed in [basic.lookup.unqual], the scopes are searched
> for a declaration in the order listed in each of the respective categories;
> name lookup ends as soon as a declaration is found for the name.
> If no declaration is found, the program is ill-formed.
In the affected code there was a use-after-move for all accesses in the constructor
body, but this UB wasn't triggered.
These types of errors are trivial to catch via clang-tidy's [clang-analyzer-cplusplus.Move].
Mic92
reviewed
Nov 8, 2024
| PosixSourceAccessor::PosixSourceAccessor(std::filesystem::path && root) | ||
| : root(std::move(root)) | ||
| PosixSourceAccessor::PosixSourceAccessor(std::filesystem::path && argRoot) | ||
| : root(std::move(argRoot)) |
Member
|
Adding clang-tidy should now be easier with meson because we get a |
Mic92
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Nov 8, 2024
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…1837 fix(libutil/posix-source-accessor.cc): get rid of use-after-move bug (backport #11837)
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Naming class member variables the same as constructor arguments is a very slippery slope because of how member variable names get resolved. Compiler is not very helpful here and we need static analysis to forbid this kind of stuff.
The following example illustrates the cause quite well:
From N4861 6.5.1 Unqualified name lookup:
In the affected code there was a use-after-move for all accessses in the constructor body, but this UB wasn't triggered.
These types of errors are trivial to catch via clang-tidy's [clang-analyzer-cplusplus.Move].
Motivation
UB is bad.
Context
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