The IntelliSense process may crash if two template constexpr functions have the same name

[sean-mcmanus]

Use

template <typename T>
constexpr void func()
{
int i1 = 5;
int b;
}

template <typename T>
constexpr void func()
{
    // <-- Type i
}

Type i where indicted.

Bug: The IntelliSense process crashes. Other repros are possible that don't require edits and other crashes may happen when putting the cursor on an identifier (reference highlighting).

I originally reproed it on Mac with the clang 17 preprocessed system headers but without the proper defines set, which causes two system library functions with different overloads to be treated as "the same" due to one of the differentiating arguments being an "error type" (e.g. __find_end).

This repros with 1.26.3, but 1.27.0 might repro it with additional code samples/edits too.

The internal issue is 2528486.

[sean-mcmanus]

There were 3 different crash scenarios, the could repro when }} was added before system headers on Mac due to that causing certain definitions to be skipped resulting in IntelliSense incorrectly parsing function as duplicates.