Additional tce tests

[Borgerr]

r? @oli-obk

Adds known-bug tests for LLVM emissions regarding indirect operands for TCE. Also includes a test, indexer.rs, referring to function_table behavior described by the RFC.

Depends on #144232

Closes #144293

[rustbot]

oli-obk is not on the review rotation at the moment.
They may take a while to respond.

[rustbot]

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

[oli-obk]

You're gonna need the kind of //@normalize-stderr attributes as other ICE tests have, or just add the test to tests/crashes

[WaffleLapkin]

What do you mean by "decision on verbiage"?.. What is this test even testing?

you can make the test pass (hopefully) by just replacing &dyn Fn(usize) with fn(usize)

[Borgerr]

"Decision on verbiage" was meant to indicate more discussion on examples given in that part of the RFC. From what I could see, nobody had tested that particular example of tail-calling something from a function table, and I was curious as to whether it'd work as desired, as it's kind of an operation. Didn't look too close in that regard though, admittedly.
I can indicate that better with a new comment, thanks for pointing that out.

Test also does pass with the described change. Push coming in a moment. However, it does feel a little silly to include now, so if input indicates I should remove it, I will.