1 files changed, 46 insertions, 38 deletions

diff --git a/src/go/types/check.go b/src/go/types/check.go
index d1672837b8..69e9466a8b 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -8,6 +8,7 @@ package types
 
 import (
 	"errors"
+	"fmt"
 	"go/ast"
 	"go/constant"
 	"go/token"
@@ -69,6 +70,12 @@ type importKey struct {
 	path, dir string
 }
 
+// A dotImportKey describes a dot-imported object in the given scope.
+type dotImportKey struct {
+	scope *Scope
+	obj   Object
+}
+
 // A Checker maintains the state of the type checker.
 // It must be created with NewChecker.
 type Checker struct {
@@ -78,18 +85,20 @@ type Checker struct {
 	fset *token.FileSet
 	pkg  *Package
 	*Info
-	nextId uint64                     // unique Id for type parameters (first valid Id is 1)
-	objMap map[Object]*declInfo       // maps package-level objects and (non-interface) methods to declaration info
-	impMap map[importKey]*Package     // maps (import path, source directory) to (complete or fake) package
-	posMap map[*Interface][]token.Pos // maps interface types to lists of embedded interface positions
-	typMap map[string]*Named          // maps an instantiated named type hash to a *Named type
-	pkgCnt map[string]int             // counts number of imported packages with a given name (for better error messages)
+	version version                    // accepted language version
+	nextId  uint64                     // unique Id for type parameters (first valid Id is 1)
+	objMap  map[Object]*declInfo       // maps package-level objects and (non-interface) methods to declaration info
+	impMap  map[importKey]*Package     // maps (import path, source directory) to (complete or fake) package
+	posMap  map[*Interface][]token.Pos // maps interface types to lists of embedded interface positions
+	typMap  map[string]*Named          // maps an instantiated named type hash to a *Named type
+	pkgCnt  map[string]int             // counts number of imported packages with a given name (for better error messages)
 
 	// information collected during type-checking of a set of package files
 	// (initialized by Files, valid only for the duration of check.Files;
 	// maps and lists are allocated on demand)
-	files            []*ast.File                             // package files
-	unusedDotImports map[*Scope]map[*Package]*ast.ImportSpec // unused dot-imported packages
+	files        []*ast.File               // package files
+	imports      []*PkgName                // list of imported packages
+	dotImportMap map[dotImportKey]*PkgName // maps dot-imported objects to the package they were dot-imported through
 
 	firstErr error                 // first error encountered
 	methods  map[*TypeName][]*Func // maps package scope type names to associated non-blank (non-interface) methods
@@ -106,22 +115,6 @@ type Checker struct {
 	indent int // indentation for tracing
 }
 
-// addUnusedImport adds the position of a dot-imported package
-// pkg to the map of dot imports for the given file scope.
-func (check *Checker) addUnusedDotImport(scope *Scope, pkg *Package, spec *ast.ImportSpec) {
-	mm := check.unusedDotImports
-	if mm == nil {
-		mm = make(map[*Scope]map[*Package]*ast.ImportSpec)
-		check.unusedDotImports = mm
-	}
-	m := mm[scope]
-	if m == nil {
-		m = make(map[*Package]*ast.ImportSpec)
-		mm[scope] = m
-	}
-	m[pkg] = spec
-}
-
 // addDeclDep adds the dependency edge (check.decl -> to) if check.decl exists
 func (check *Checker) addDeclDep(to Object) {
 	from := check.decl
@@ -187,17 +180,23 @@ func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Ch
 		info = new(Info)
 	}
 
+	version, err := parseGoVersion(conf.GoVersion)
+	if err != nil {
+		panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
+	}
+
 	return &Checker{
-		conf:   conf,
-		fset:   fset,
-		pkg:    pkg,
-		Info:   info,
-		nextId: 1,
-		objMap: make(map[Object]*declInfo),
-		impMap: make(map[importKey]*Package),
-		posMap: make(map[*Interface][]token.Pos),
-		typMap: make(map[string]*Named),
-		pkgCnt: make(map[string]int),
+		conf:    conf,
+		fset:    fset,
+		pkg:     pkg,
+		Info:    info,
+		version: version,
+		nextId:  1,
+		objMap:  make(map[Object]*declInfo),
+		impMap:  make(map[importKey]*Package),
+		posMap:  make(map[*Interface][]token.Pos),
+		typMap:  make(map[string]*Named),
+		pkgCnt:  make(map[string]int),
 	}
 }
 
@@ -206,7 +205,8 @@ func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Ch
 func (check *Checker) initFiles(files []*ast.File) {
 	// start with a clean slate (check.Files may be called multiple times)
 	check.files = nil
-	check.unusedDotImports = nil
+	check.imports = nil
+	check.dotImportMap = nil
 
 	check.firstErr = nil
 	check.methods = nil
@@ -276,6 +276,9 @@ func (check *Checker) checkFiles(files []*ast.File) (err error) {
 	if !check.conf.DisableUnusedImportCheck {
 		check.unusedImports()
 	}
+	// no longer needed - release memory
+	check.imports = nil
+	check.dotImportMap = nil
 
 	check.recordUntyped()
 
@@ -284,6 +287,9 @@ func (check *Checker) checkFiles(files []*ast.File) (err error) {
 	}
 
 	check.pkg.complete = true
+
+	// TODO(rFindley) There's more memory we should release at this point.
+
 	return
 }
 
@@ -334,7 +340,9 @@ func (check *Checker) recordTypeAndValue(x ast.Expr, mode operandMode, typ Type,
 	}
 	if mode == constant_ {
 		assert(val != nil)
-		assert(typ == Typ[Invalid] || isConstType(typ))
+		// We check is(typ, IsConstType) here as constant expressions may be
+		// recorded as type parameters.
+		assert(typ == Typ[Invalid] || is(typ, IsConstType))
 	}
 	if m := check.Types; m != nil {
 		m[x] = TypeAndValue{mode, typ, val}
@@ -388,8 +396,8 @@ func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
 func (check *Checker) recordInferred(call ast.Expr, targs []Type, sig *Signature) {
 	assert(call != nil)
 	assert(sig != nil)
-	if m := check.Inferred; m != nil {
-		m[call] = Inferred{targs, sig}
+	if m := check._Inferred; m != nil {
+		m[call] = _Inferred{targs, sig}
 	}
 }