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garble/testdata
Daniel Martí 2ee9cf7a43 support go:linkname directives pointing at methods
This is not common, but it is done by a few projects.
Namely, github.com/goccy/go-json reached into reflect's guts,
which included a number of methods:

	internal/runtime/rtype.go
	11://go:linkname rtype_Align reflect.(*rtype).Align
	19://go:linkname rtype_FieldAlign reflect.(*rtype).FieldAlign
	27://go:linkname rtype_Method reflect.(*rtype).Method
	35://go:linkname rtype_MethodByName reflect.(*rtype).MethodByName
	[...]

Add tests for such go:linkname directives pointing at methods.
Note that there are two possible symbol string variants;
"pkg/path.(*Receiver).method" for methods with pointer receivers,
and "pkg/path.Receiver.method" for the rest.

We can't assume that the presence of two dots means a method either.
For example, a package path may be "pkg/path.with.dots",
and so "pkg/path.with.dots.SomeFunc" is the function "SomeFunc"
rather than the method "SomeFunc" on a type "dots".
To account for this ambiguity, rather than splitting on the last dot
like we used to, try to find a package path prefix by splitting on an
increasing number of first dots.

This can in theory still be ambiguous. For example,
we could have the package "pkg/path" expose the method "foo.bar",
and the package "pkg/path.foo" expose the func "bar".
Then, the symbol string "pkg/path.foo.bar" could mean either of them.
However, this seems extremely unlikely to happen in practice,
and I'm not sure that Go's toolchain would support it either.

I also noticed that goccy/go-json still failed to build after the fix.
The reason was that the type reflect.rtype wasn't being obfuscated.
We could, and likely should, teach our assembly and linkname
transformers about which names we chose not to obfuscate due to the use
of reflection. However, in this particular case, reflect's own types
can be obfuscated safely, so just do that.

Fixes #656.
1 year ago
..
bench redesign benchmark to be more useful and realistic 2 years ago
mod Fix removing named imports and fix removing imports with init() methods 2 years ago
script support go:linkname directives pointing at methods 1 year ago