Clang diagnostics issue: Candidate ignored without reason provided

[jeremy-rifkin]

Pardon the large demo, this came up when resting something with a library I've been writing.

In this example, https://godbolt.org/z/1o4nr958b, clang errors

<source>:1232:5: error: no matching function for call to 'foo'
    foo<bar(2)>();
    ^~~~~~~~~~~
<source>:1224:22: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'X'
template<int X> void foo() {}
                     ^

Without providing a reason why the explicitly-specified argument is invalid. GCC reports that the macro is expanding to have a problematic local static variable.

Similarly after removing the static qualifiers there are other problems with calling non-constexpr functions but clang still does not provide a diagnostic as to why the explicitly-specified argument is invalid https://godbolt.org/z/7xGrecxfe.

[jeremy-rifkin]

Here's another much smaller example showing a clear regression from clang 12 -> 13 https://godbolt.org/z/PeorTPdaz

[stellarpower]

I hit a similar situation here (obviously much more minimal than my real-world example or I'd have spotted it ;))

Current trunk output:

<source>:11:25: error: no matching function for call to 'f'
   11 | constexpr auto Result = f<List>();
      |                         ^~~~~~~
<source>:4:27: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'T'
    4 | template<typename T> auto f(){
      |                           ^
1 error generated.

What I'd like:

<source>:11:25: error: no matching function for call to 'f'
   11 | constexpr auto Result = f<List>();
      |                         ^~~~~~~
<source>:4:27: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'T'
    4 | template<typename T> auto f(){
      |                           ^
<source>:11:25: note: List is not a type but a (..., e.g. constexpr variable in namespace scope). Did you forget to use `decltype`?
   11 | constexpr auto Result = f<List>();
      |                           ^^^^

1 error generated.