[Issue 24101] New: Incorrect mangling for parameter of template member function

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24101

          Issue ID: 24101
           Summary: Incorrect mangling for parameter of template member
                    function
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: snarwin+bugzilla at gmail.com

Example program:

--- test.d
extern(C++)
struct S
{
    void fun(T)(T t) {}
    alias fun_int = fun!int;
}
--- main.cpp
struct S
{
    template<typename T>
    void fun(T t);
};

int main()
{
    S s;
    s.fun<int>(0);
    return 0;
}
---

When compiling test.d with DMD 2.104.0 and main.cpp with either gcc or clang,
the resulting program fails to link. The cause is inconsistent mangling of the
member function S::fun<int>.

---
$ nm main.o test.o | grep fun
                 U _ZN1S3funIiEEvT_
0000000000000000 W _ZN1S3funIiEEvi
---

GCC and clang correctly mangle the parameter type of S::fun<int> as `T_` (first
template argument), but DMD incorrectly mangles it as `i` (int).

--