all: merge master into release-branch.go1.7

Change-Id: I177856ea2bc9943cbde28ca9afa145b6ea5b0942

5 files changed, 48 insertions, 11 deletions

diff --git a/src/cmd/doc/doc_test.go b/src/cmd/doc/doc_test.go
index 5cb1ec990e..453a3d53aa 100644
--- a/src/cmd/doc/doc_test.go
+++ b/src/cmd/doc/doc_test.go
@@ -61,6 +61,7 @@ var tests = []test{
 			`var ExportedVariable = 1`,                              // Simple variable.
 			`var VarOne = 1`,                                        // First entry in variable block.
 			`func ExportedFunc\(a int\) bool`,                       // Function.
+			`func ReturnUnexported\(\) unexportedType`,              // Function with unexported return type.
 			`type ExportedType struct { ... }`,                      // Exported type.
 			`const ExportedTypedConstant ExportedType = iota`,       // Typed constant.
 			`const ExportedTypedConstant_unexported unexportedType`, // Typed constant, exported for unexported type.
@@ -89,9 +90,10 @@ var tests = []test{
 		"full package with u",
 		[]string{`-u`, p},
 		[]string{
-			`const ExportedConstant = 1`,      // Simple constant.
-			`const internalConstant = 2`,      // Internal constants.
-			`func internalFunc\(a int\) bool`, // Internal functions.
+			`const ExportedConstant = 1`,               // Simple constant.
+			`const internalConstant = 2`,               // Internal constants.
+			`func internalFunc\(a int\) bool`,          // Internal functions.
+			`func ReturnUnexported\(\) unexportedType`, // Function with unexported return type.
 		},
 		[]string{
 			`Comment about exported constant`,  // No comment for simple constant.
@@ -221,6 +223,7 @@ var tests = []test{
 			`func \(ExportedType\) ExportedMethod\(a int\) bool`,
 			`const ExportedTypedConstant ExportedType = iota`, // Must include associated constant.
 			`func ExportedTypeConstructor\(\) \*ExportedType`, // Must include constructor.
+			`io.Reader.*Comment on line with embedded Reader.`,
 		},
 		[]string{
 			`unexportedField`,                // No unexported field.
@@ -228,6 +231,7 @@ var tests = []test{
 			`Comment about exported method.`, // No comment about exported method.
 			`unexportedMethod`,               // No unexported method.
 			`unexportedTypedConstant`,        // No unexported constant.
+			`error`,                          // No embedded error.
 		},
 	},
 	// Type -u with unexported fields.
@@ -243,6 +247,8 @@ var tests = []test{
 			`\*ExportedEmbeddedType.*Comment on line with exported embedded \*field.`,
 			`unexportedType.*Comment on line with unexported embedded field.`,
 			`\*unexportedType.*Comment on line with unexported embedded \*field.`,
+			`io.Reader.*Comment on line with embedded Reader.`,
+			`error.*Comment on line with embedded error.`,
 			`func \(ExportedType\) unexportedMethod\(a int\) bool`,
 			`unexportedTypedConstant`,
 		},
@@ -274,6 +280,8 @@ var tests = []test{
 			`type ExportedInterface interface`, // Interface definition.
 			`Comment before exported method.*\n.*ExportedMethod\(\)` +
 				`.*Comment on line with exported method`,
+			`io.Reader.*Comment on line with embedded Reader.`,
+			`error.*Comment on line with embedded error.`,
 			`Has unexported methods`,
 		},
 		[]string{
@@ -293,6 +301,8 @@ var tests = []test{
 			`Comment before exported method.*\n.*ExportedMethod\(\)` +
 				`.*Comment on line with exported method`,
 			`unexportedMethod\(\).*Comment on line with unexported method.`,
+			`io.Reader.*Comment on line with embedded Reader.`,
+			`error.*Comment on line with embedded error.`,
 		},
 		[]string{
 			`Has unexported methods`,
diff --git a/src/cmd/doc/pkg.go b/src/cmd/doc/pkg.go
index efd681d514..defddfd74a 100644
--- a/src/cmd/doc/pkg.go
+++ b/src/cmd/doc/pkg.go
@@ -317,7 +317,9 @@ func (pkg *Package) funcSummary(funcs []*doc.Func, showConstructors bool) {
 		isConstructor = make(map[*doc.Func]bool)
 		for _, typ := range pkg.doc.Types {
 			for _, constructor := range typ.Funcs {
-				isConstructor[constructor] = true
+				if isExported(typ.Name) {
+					isConstructor[constructor] = true
+				}
 			}
 		}
 	}
@@ -494,14 +496,19 @@ func trimUnexportedElems(spec *ast.TypeSpec) {
 	}
 	switch typ := spec.Type.(type) {
 	case *ast.StructType:
-		typ.Fields = trimUnexportedFields(typ.Fields, "fields")
+		typ.Fields = trimUnexportedFields(typ.Fields, false)
 	case *ast.InterfaceType:
-		typ.Methods = trimUnexportedFields(typ.Methods, "methods")
+		typ.Methods = trimUnexportedFields(typ.Methods, true)
 	}
 }
 
 // trimUnexportedFields returns the field list trimmed of unexported fields.
-func trimUnexportedFields(fields *ast.FieldList, what string) *ast.FieldList {
+func trimUnexportedFields(fields *ast.FieldList, isInterface bool) *ast.FieldList {
+	what := "methods"
+	if !isInterface {
+		what = "fields"
+	}
+
 	trimmed := false
 	list := make([]*ast.Field, 0, len(fields.List))
 	for _, field := range fields.List {
@@ -511,12 +518,23 @@ func trimUnexportedFields(fields *ast.FieldList, what string) *ast.FieldList {
 			// Nothing else is allowed.
 			switch ident := field.Type.(type) {
 			case *ast.Ident:
+				if isInterface && ident.Name == "error" && ident.Obj == nil {
+					// For documentation purposes, we consider the builtin error
+					// type special when embedded in an interface, such that it
+					// always gets shown publicly.
+					list = append(list, field)
+					continue
+				}
 				names = []*ast.Ident{ident}
 			case *ast.StarExpr:
 				// Must have the form *identifier.
-				if ident, ok := ident.X.(*ast.Ident); ok {
+				// This is only valid on embedded types in structs.
+				if ident, ok := ident.X.(*ast.Ident); ok && !isInterface {
 					names = []*ast.Ident{ident}
 				}
+			case *ast.SelectorExpr:
+				// An embedded type may refer to a type in another package.
+				names = []*ast.Ident{ident.Sel}
 			}
 			if names == nil {
 				// Can only happen if AST is incorrect. Safe to continue with a nil list.
diff --git a/src/cmd/doc/testdata/pkg.go b/src/cmd/doc/testdata/pkg.go
index 5f79414b33..6a52ac2f65 100644
--- a/src/cmd/doc/testdata/pkg.go
+++ b/src/cmd/doc/testdata/pkg.go
@@ -66,6 +66,8 @@ type ExportedType struct {
 	*ExportedEmbeddedType     // Comment on line with exported embedded *field.
 	unexportedType            // Comment on line with unexported embedded field.
 	*unexportedType           // Comment on line with unexported embedded *field.
+	io.Reader                 // Comment on line with embedded Reader.
+	error                     // Comment on line with embedded error.
 }
 
 // Comment about exported method.
@@ -96,6 +98,8 @@ type ExportedInterface interface {
 	// Comment before exported method.
 	ExportedMethod()   // Comment on line with exported method.
 	unexportedMethod() // Comment on line with unexported method.
+	io.Reader          // Comment on line with embedded Reader.
+	error              // Comment on line with embedded error.
 }
 
 // Comment about unexported type.
@@ -119,3 +123,6 @@ const unexportedTypedConstant unexportedType = 1 // In a separate section to tes
 // For case matching.
 const CaseMatch = 1
 const Casematch = 2
+
+func ReturnUnexported() unexportedType { return 0 }
+func ReturnExported() ExportedType     { return ExportedType{} }
diff --git a/src/runtime/sys_darwin_386.s b/src/runtime/sys_darwin_386.s
index 83f4709f38..b5e65e6869 100644
--- a/src/runtime/sys_darwin_386.s
+++ b/src/runtime/sys_darwin_386.s
@@ -196,15 +196,16 @@ timeloop:
 
 systime:
 	// Fall back to system call (usually first call in this thread)
-	LEAL	12(SP), AX	// must be non-nil, unused
+	LEAL	16(SP), AX	// must be non-nil, unused
 	MOVL	AX, 4(SP)
 	MOVL	$0, 8(SP)	// time zone pointer
+	MOVL	$0, 12(SP)	// required as of Sierra; Issue 16570
 	MOVL	$116, AX
 	INT	$0x80
 	CMPL	AX, $0
 	JNE	inreg
-	MOVL	12(SP), AX
-	MOVL	16(SP), DX
+	MOVL	16(SP), AX
+	MOVL	20(SP), DX
 inreg:
 	// sec is in AX, usec in DX
 	// convert to DX:AX nsec
diff --git a/src/runtime/sys_darwin_amd64.s b/src/runtime/sys_darwin_amd64.s
index e4837ce291..ea2cc068f6 100644
--- a/src/runtime/sys_darwin_amd64.s
+++ b/src/runtime/sys_darwin_amd64.s
@@ -157,6 +157,7 @@ systime:
 	// Fall back to system call (usually first call in this thread).
 	MOVQ	SP, DI
 	MOVQ	$0, SI
+	MOVQ	$0, DX  // required as of Sierra; Issue 16570
 	MOVL	$(0x2000000+116), AX
 	SYSCALL
 	CMPQ	AX, $0