x/tools/go/ssa: stop using deprecated x/tools/go/loader in unit tests

[timothy-king]

ssa - @timothy-king
go/ssa/ssautil/switch_test.go
go/ssa/ssautil/load.go
go/ssa/example_test.go
go/ssa/interp/interp_test.go
go/ssa/builder_generic_test.go
go/ssa/builder_test.go

refactor/rename - these are deprecated anyway - see https://github.com/golang/go/issues/69538
refactor/rename/rename.go
refactor/rename/mvpkg.go
refactor/rename/spec.go
refactor/rename/check.go

eg - in progress https://go.dev/cl/616215
refactor/eg/eg_test.go

gcimporter - in progress https://go.dev/cl/614676
internal/gcimporter/iexport_test.go

objectpath - in progress https://go.dev/cl/614678 
go/types/objectpath/objectpath_test.go
go/types/objectpath/objectpath_go118_test.go

callgraph - https://go.dev/cl/614679
go/callgraph/cha/cha_test.go
go/callgraph/vta/helpers_test.go
go/callgraph/callgraph_test.go
go/callgraph/static/static_test.go

[gopherbot]

Change https://go.dev/cl/614735 mentions this issue: go/ssa: add test utility for building a single file

[gopherbot]

Change https://go.dev/cl/614717 mentions this issue: go/ssa: remove loader utility functions

[gopherbot]

Change https://go.dev/cl/614116 mentions this issue: go/ssa: migrate source_test.go away from loader

[gopherbot]

Change https://go.dev/cl/614676 mentions this issue: internal/gcimporter: rewrite TestIExportData_stdlib using go/packages

[gopherbot]

Change https://go.dev/cl/614678 mentions this issue: go/types/objectpath: use go/packages instead of go/loader in tests

[gopherbot]

Change https://go.dev/cl/614679 mentions this issue: go/callgraph: rewrite tests to use go/packages not go/loader

[adonovan]

Once we're done here we should step back and study all calls to go/packages from within tests and try to come up with some good testing abstractions (perhaps making greater use of txtar). There's a lot of ad hoc intermediate abstractions (like loadFile and loadPackages) that could perhaps be smoothed out, making future tests easier to write.

[gopherbot]

Change https://go.dev/cl/614895 mentions this issue: cmd/{callgraph,ssadump}, gopackages: make -tags flags work

[gopherbot]

Change https://go.dev/cl/614955 mentions this issue: go/ssa: migrate some tests in build_test.go away from loader

[xieyuschen]

Hi @adonovan @timothy-king , currently the goMod in go/ssa testutil_test.go receives a pkgname instead of a typical module name. This approach makes the test case of instantiated functions ambiguous.

For example, if the module name is example.com and the package name is p, the instantiated function of Lambda will be Lambda[example.com.A](qualified identifier) instead of Lambda[p.A]. You can see a lot of this kind of testing cases in the previous CL. I abandoned it because it mixes too many changes together. Another active CL is: https://go-review.googlesource.com/c/tools/+/614995.

package p

type I interface {
	Foo()
}

type A int
func (a A) Foo() {}

func Lambda[T I]() func() func(T) {
	return func() func(T) {
		return T.Foo
	}
}

func entry(i int, a A) int {
	Lambda[A]()()(a)

}

Current testing doesn't reflect this differences between module name and package name in instantiated functions. I believe it's worth doing to reflect such differences. hdyt?

The possible changes are:

• use hard-coded example.com or golang.org/x/tools as fixed module name when calling goMod in buildPackage
• change all related instantiated test cases from <package_name>.Ident to <module_name>.Ident.

[gopherbot]

Change https://go.dev/cl/614975 mentions this issue: go/ssa: migrate TestTypeparamTest away from loader

[gopherbot]

Change https://go.dev/cl/615015 mentions this issue: go/ssa: migrate TestGenericAliases away from loader

[gopherbot]

Change https://go.dev/cl/615035 mentions this issue: go/ssa/ssautil: migrate switch_test.go away from loader

[gopherbot]

Change https://go.dev/cl/615016 mentions this issue: go/ssa/interp: migrate interp_test.go away from loader

[gopherbot]

Change https://go.dev/cl/614995 mentions this issue: go/ssa: migrate TestGenericFunctionSelector away from loader

[gopherbot]

Change https://go.dev/cl/616215 mentions this issue: refactor/eg: rewrite test without go/loader