Clang hits assertion when using virual consteval functions: VTableBuilder.cpp:2281 `I != MethodVTableIndices.end() && "Did not find index!"' failed.`

[ArXen42]

How to reproduce

struct Base
{
	consteval virtual int Get() const = 0;
};

struct Derived : Base
{
	consteval int Get() const override
	{
		return 42;
	}
};

int main()
{
	constexpr Derived a;

	auto val = a.Get();
	return 0;
}

Compiler explorer link (clang-14, -std=c++20, no optimizations or other options):
https://godbolt.org/z/vhqGqvf1z

Replacing 'consteval' with 'constexpr', moving a creation out of the function scope or removing inheritance seems to fix this compiler crash.

Attached cpp/sh crash reproduction files from my local compiler (clang 13.0.1-2 from Arch Linux repos):
main-fee9e9..zip

[llvmbot]

@llvm/issue-subscribers-clang-codegen

[fhahn]

Also crashes with current main: https://godbolt.org/z/7n78vf46T

[llvmbot]

@llvm/issue-subscribers-c-20

[nicolas17]

The assertion happens while generating debug info, so -g is required to reproduce (in godbolt, -g is the default, and -g0 makes it not assert).

Bisect pointed me at 51e4aa8, which is a re-land of 3bab88b which also causes the assert.