go.tools/go/types: towards permitting adding additional package files incrementally

Another small step towards resolving issue 7114.

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/72230043

go/types/check.go

@@ -26,6 +26,14 @@ type exprInfo struct {
 	val   exact.Value // constant value; or nil (if not a constant)
 }
 
+// funcInfo stores the information required for type-checking a function.
+type funcInfo struct {
+	name string    // for debugging/tracing only
+	decl *declInfo // for cycle detection
+	sig  *Signature
+	body *ast.BlockStmt
+}
+
 // A context represents the context within which an object is type-checked.
 type context struct {
 	decl          *declInfo   // package-level declaration whose init expression/function body is checked
@@ -83,6 +91,10 @@ func (check *checker) rememberUntyped(e ast.Expr, lhs bool, typ *Basic, val exac
 	m[e] = exprInfo{lhs, typ, val}
 }
 
+func (check *checker) later(name string, decl *declInfo, sig *Signature, body *ast.BlockStmt) {
+	check.funcs = append(check.funcs, funcInfo{name, decl, sig, body})
+}
+
 func (check *checker) delay(f func()) {
 	check.delayed = append(check.delayed, f)
 }
@@ -175,12 +187,6 @@ func (check *checker) files(files []*ast.File) (err error) {
 		}
 	}
 
-	// copy check.InitOrder back to incoming *info if necessary
-	// (In case of early (error) bailout, this is not done, but we don't care in that case.)
-	// if info != nil {
-	// 	info.InitOrder = check.InitOrder
-	// }
-
 	pkg.complete = true
 	return
 }

go/types/decl.go

@@ -265,13 +265,6 @@ func (check *checker) typeDecl(obj *TypeName, typ ast.Expr, def *Named, path []*
 	delete(check.methods, obj.name) // we don't need them anymore
 }
 
-type funcInfo struct {
-	name string    // for debugging/tracing only
-	decl *declInfo // for cycle detection
-	sig  *Signature
-	body *ast.BlockStmt
-}
-
 func (check *checker) funcDecl(obj *Func, decl *declInfo) {
 	assert(obj.typ == nil)
 
@@ -290,7 +283,7 @@ func (check *checker) funcDecl(obj *Func, decl *declInfo) {
 	// function body must be type-checked after global declarations
 	// (functions implemented elsewhere have no body)
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
-		check.funcs = append(check.funcs, funcInfo{obj.name, decl, sig, fdecl.Body})
+		check.later(obj.name, decl, sig, fdecl.Body)
 	}
 }
 

go/types/resolver.go

@@ -116,8 +116,15 @@ func (check *checker) resolveFiles(files []*ast.File) {
 		importer = DefaultImport
 	}
 
+	// pkgImports is the set of packages already imported by any package file seen
+	// so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
+	// it (pkg.imports may not be empty if we are checking test files incrementally).
+	var pkgImports = make(map[*Package]bool)
+	for _, imp := range pkg.imports {
+		pkgImports[imp] = true
+	}
+
 	var (
-		seenPkgs   = make(map[*Package]bool) // imported packages that have been seen already
 		fileScopes []*Scope                 // file scope for each file
 		dotImports []map[*Package]token.Pos // positions of dot-imports for each file
 	)
@@ -168,8 +175,8 @@ func (check *checker) resolveFiles(files []*ast.File) {
 						// add package to list of explicit imports
 						// (this functionality is provided as a convenience
 						// for clients; it is not needed for type-checking)
-						if !seenPkgs[imp] {
-							seenPkgs[imp] = true
+						if !pkgImports[imp] {
+							pkgImports[imp] = true
 							if imp != Unsafe {
 								pkg.imports = append(pkg.imports, imp)
 							}
@@ -343,7 +350,7 @@ func (check *checker) resolveFiles(files []*ast.File) {
 			}
 		}
 	}
-	seenPkgs = nil // not needed anymore
+	pkgImports = nil // not needed anymore
 
 	// Phase 2: Verify that objects in package and file scopes have different names.