[abi] mangled name issues for requires-clauses.

[hokein]

Example 1:

template <typename T>
concept C = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<F>;
    }
  {}
};

void k() {
 // mangled name for the Foo<double>::Foo constructor: _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
 Foo<double> f(1);
}

The mangled name _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE is demangled incorrectly (note that TL0):

$ ./bin/llvm-cxxfilt _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
Foo<double>::Foo<int>(int) requires requires { requires C<TL0_>; }

Example 2:

template <typename T>
concept C = true;
template <typename T, typename U>
concept C2 = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<Foo>;
      requires C<T>;
      requires C2<F, F>;
    }
  {}
};

void k() {
   // mangled name is _ZN3FooIdEC2IiEET_QrqQ1CIS_IS2_EEQ1CIS2_EQ2C2ITL0__S5_EE
   Foo<double> f(1);
}

The mangled name can not be demangled by llvm-cxxfilt.

[llvmbot]

@llvm/issue-subscribers-tools-llvm-cxxfilt

Author: Haojian Wu (hokein)

Example 1:

template <typename T>
concept C = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<F>;
    }
  {}
};

void k() {
 // mangled name for the Foo<double>::Foo constructor: _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
 Foo<double> f(1);
}

The mangled name _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE is demangled incorrectly (note that TL0):

$ ./bin/llvm-cxxfilt _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
Foo<double>::Foo<int>(int) requires requires { requires C<TL0_>; }

Example 2:

template <typename T>
concept C = true;
template <typename T, typename U>
concept C2 = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<Foo>;
      requires C<T>;
      requires C2<F, F>;
    }
  {}
};

void k() {
   // mangled name is _ZN3FooIdEC2IiEET_QrqQ1CIS_IS2_EEQ1CIS2_EQ2C2ITL0__S5_EE
   Foo<double> f(1);
}

The mangled name can not be demangled by llvm-cxxfilt.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Haojian Wu (hokein)

Example 1:

template <typename T>
concept C = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<F>;
    }
  {}
};

void k() {
 // mangled name for the Foo<double>::Foo constructor: _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
 Foo<double> f(1);
}

The mangled name _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE is demangled incorrectly (note that TL0):

$ ./bin/llvm-cxxfilt _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE
Foo<double>::Foo<int>(int) requires requires { requires C<TL0_>; }

Example 2:

template <typename T>
concept C = true;
template <typename T, typename U>
concept C2 = true;

template <typename T>
struct Foo {
  template <typename F>
  explicit Foo(F f)
    requires requires {
      requires C<Foo>;
      requires C<T>;
      requires C2<F, F>;
    }
  {}
};

void k() {
   // mangled name is _ZN3FooIdEC2IiEET_QrqQ1CIS_IS2_EEQ1CIS2_EQ2C2ITL0__S5_EE
   Foo<double> f(1);
}

The mangled name can not be demangled by llvm-cxxfilt.

[hokein]

The mangled name _ZN3FooIdEC2IiEET_QrqQ1CITL0__EE is demangled incorrectly (note that TL0):

This is not fully supported by the demangler yet, there is a TODO at https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/Demangle/ItaniumDemangle.h#L5675-L5681

[hokein]

In example 2, _ZN3FooIdEC2IiEET_QrqQ1CIS_IS2_EEQ1CIS2_EQ2C2ITL0__S5_EE, the demangler fails when parsing the substitution S5 because it attempts to access Subs[5+1], which is out of bounds. The Subs array only has 6 elements:
[Foo, Foo<double>, Foo<double>::Foo<double>, int, Foo<int>, TL0_].

[shafik]

CC @rjmccall @zygoloid