[dev.typeparams] cmd/compile: add "check" field to noder.gcimports

The unified IR importer needs access to the *types2.Checker instance
to lazily construct objects and types. Eventually, maybe the
types2.Importer API can be extended to add the Checker as another
parameter (or more likely something like an ImportConfig struct), but
right now we can handle this ourselves as long as we forgo the
types2.(*Config).Check convenience wrapper.

Updates #46449.

Change-Id: I89c41d5d47c224a58841247cd236cd9f701a23a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/327053
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

src/cmd/compile/internal/noder/import.go

@@ -31,8 +31,8 @@ import (
 	"cmd/internal/src"
 )
 
-// Temporary import helper to get type2-based type-checking going.
 type gcimports struct {
+	check    *types2.Checker
 	packages map[string]*types2.Package
 }
 
@@ -45,7 +45,7 @@ func (m *gcimports) ImportFrom(path, srcDir string, mode types2.ImportMode) (*ty
 		panic("mode must be 0")
 	}
 
-	_, pkg, err := readImportFile(path, typecheck.Target, m.packages)
+	_, pkg, err := readImportFile(path, typecheck.Target, m.check, m.packages)
 	return pkg, err
 }
 
@@ -176,7 +176,7 @@ func importfile(decl *syntax.ImportDecl) *types.Pkg {
 		return nil
 	}
 
-	pkg, _, err := readImportFile(path, typecheck.Target, nil)
+	pkg, _, err := readImportFile(path, typecheck.Target, nil, nil)
 	if err != nil {
 		base.Errorf("%s", err)
 		return nil
@@ -208,7 +208,7 @@ func parseImportPath(pathLit *syntax.BasicLit) (string, error) {
 // readImportFile reads the import file for the given package path and
 // returns its types.Pkg representation. If packages is non-nil, the
 // types2.Package representation is also returned.
-func readImportFile(path string, target *ir.Package, packages map[string]*types2.Package) (pkg1 *types.Pkg, pkg2 *types2.Package, err error) {
+func readImportFile(path string, target *ir.Package, check *types2.Checker, packages map[string]*types2.Package) (pkg1 *types.Pkg, pkg2 *types2.Package, err error) {
 	path, err = resolveImportPath(path)
 	if err != nil {
 		return

src/cmd/compile/internal/noder/irgen.go

@@ -20,7 +20,7 @@ import (
 
 // checkFiles configures and runs the types2 checker on the given
 // parsed source files and then returns the result.
-func checkFiles(noders []*noder, importer types2.Importer) (posMap, *types2.Package, *types2.Info) {
+func checkFiles(noders []*noder) (posMap, *types2.Package, *types2.Info) {
 	if base.SyntaxErrors() != 0 {
 		base.ErrorExit()
 	}
@@ -34,6 +34,9 @@ func checkFiles(noders []*noder, importer types2.Importer) (posMap, *types2.Pack
 	}
 
 	// typechecking
+	importer := gcimports{
+		packages: make(map[string]*types2.Package),
+	}
 	conf := types2.Config{
 		GoVersion:             base.Flag.Lang,
 		IgnoreLabels:          true, // parser already checked via syntax.CheckBranches mode
@@ -43,7 +46,7 @@ func checkFiles(noders []*noder, importer types2.Importer) (posMap, *types2.Pack
 			terr := err.(types2.Error)
 			base.ErrorfAt(m.makeXPos(terr.Pos), "%s", terr.Msg)
 		},
-		Importer: importer,
+		Importer: &importer,
 		Sizes:    &gcSizes{},
 	}
 	info := &types2.Info{
@@ -57,7 +60,10 @@ func checkFiles(noders []*noder, importer types2.Importer) (posMap, *types2.Pack
 		// expand as needed
 	}
 
-	pkg, err := conf.Check(base.Ctxt.Pkgpath, files, info)
+	pkg := types2.NewPackage(base.Ctxt.Pkgpath, "")
+	importer.check = types2.NewChecker(&conf, pkg, info)
+	err := importer.check.Files(files)
+
 	base.ExitIfErrors()
 	if err != nil {
 		base.FatalfAt(src.NoXPos, "conf.Check error: %v", err)
@@ -69,11 +75,7 @@ func checkFiles(noders []*noder, importer types2.Importer) (posMap, *types2.Pack
 // check2 type checks a Go package using types2, and then generates IR
 // using the results.
 func check2(noders []*noder) {
-	importer := &gcimports{
+	m, pkg, info := checkFiles(noders)
-		packages: make(map[string]*types2.Package),
-	}
-
-	m, pkg, info := checkFiles(noders, importer)
 
 	if base.Flag.G < 2 {
 		os.Exit(0)