Abbreviated function template in extern "C" block generates error with bad location (original) (raw)

Extended Description

When producing an error message about an abbreviated function template appearing in an extern "C" block, Clang does not appear to have a proper diagnostic location to refer to (notice the first line of the actual output listed below).

Note: The error message itself appears to stem from words in [temp.pre] that prohibit C language linkage for templates, although [dcl.link] doesn't apply C language linkage to templates in the first place.

Compiler Explorer link: https://godbolt.org/z/GPcoMe

SOURCE ():

extern "C" { void g(auto) {} void g(void) { g(42); } }

COMPILER INVOCATION:

clang++ -cc1 -fsyntax-only -std=c++20 -Wall -Wextra -pedantic-errors -xc++ -

ACTUAL OUTPUT:

error: templates must have C++ linkage
<stdin>:1:1: note: extern "C" language linkage specification begins here
extern "C" {
^
<stdin>:3:18: error: no matching function for call to 'g'
  void g(void) { g(42); }
                 ^
<stdin>:3:8: note: candidate function not viable: requires 0 arguments, but 1 was provided
  void g(void) { g(42); }
       ^
2 errors generated.

EXPECTED OUTPUT:

(first error should point to the declarator-id of the abbreviated function template)

COMPILER VERSION INFO (clang++ -v):

clang version 12.0.0 (https://github.com/llvm/llvm-project.git f92e0d9384763913a745cbe9c757fbb40691dcd1)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/wandbox/clang-head/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64