Ambiguity between symbol visibility and linkage type in cir.func assembly format

[sitio-couto]

The following cir.func is valid and can be either a function with private linkage or a function with private symbol visibility.

cir.func private @func() -> ()

Both linkage and visibility tags are optional. In the example, only one is specified, however, it is impossible to know if private refers to linkage or symbol visibility since the keyword private is a valid value for both of these attributes.

clangir/clang/lib/CIR/Dialect/IR/CIRDialect.cpp

Lines 1305 to 1317 in 855f623

	// Default to external linkage if no keyword is provided.
	state.addAttribute(getLinkageAttrNameString(),
	GlobalLinkageKindAttr::get(
	parser.getContext(),
	parseOptionalCIRKeyword<GlobalLinkageKind>(
	parser, GlobalLinkageKind::ExternalLinkage)));
	::llvm::StringRef visAttrStr;
	if (parser.parseOptionalKeyword(&visAttrStr, {"private", "public", "nested"})
	.succeeded()) {
	state.addAttribute(visNameAttr,
	parser.getBuilder().getStringAttr(visAttrStr));
	}

[bcardosolopes]

I fixed this Friday by changing the linkage one to always be cir_private, so it's not ambiguous anymore. I found it while trying to full circle on a emitted test case (which is a good practice when doing CIRGen).

In the future I would like to get rid of the MLIR one somehow and implement our own CIR symbol rules based on linkage instead.

[sitio-couto]

Fixed in 2ae0230