librustc_codegen_ssa: exported entry function symbol is hardcoded as "main"

[Xanewok]

Seems suspicious as observed by @Zoxc here.

Could we have in theory something like (or anything else):

#[no_mangle]
#[main]
fn awesome_main() { ... }

which would make this logic wrong?

[michaelwoerister]

Yes, seems like an oversight.

[steveklabnik]

Triage; the "here" doesn't link to anything. It's not clear to me what this ticket is about, to be honest.

[Mark-Simulacrum]

This is about

rust/src/librustc_codegen_ssa/back/symbol_export.rs

Lines 178 to 182 in d20113d

	if tcx.entry_fn(LOCAL_CRATE).is_some() {
	let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new("main"));
	symbols.push((exported_symbol, SymbolExportLevel::C));
	}

-- specifically, we presume that if the crate we're compiling has a entry function then we should export the "main" symbol (which might not be what main is actually called).

But I think this is requires-nightly, since you can't rename main on stable AFAIK.

[jonas-schievink]

I wonder if #[main] should be removed in favor of using the export system for this. Then users could use my_custom_main as main; instead.

[Mark-Simulacrum]

I don't really know why you'd want main to not be called main, seems like an odd thing to allow -- and we don't on stable, so there's probably approximately zero users anyway?

Edit: basically I'd be up for removing #[main] entirely personally