go/types: clean up asT converters (step 2 of 2)

This is a clean port of CL 358774 to go/types.

Change-Id: Icba54336de2b8de7c2002d2a44cac856907178c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/360754
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/go/types/assignments.go

@@ -71,7 +71,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 	}
 
 	// A generic (non-instantiated) function value cannot be assigned to a variable.
-	if sig := toSignature(x.typ); sig != nil && sig.TypeParams().Len() > 0 {
+	if sig := asSignature(x.typ); sig != nil && sig.TypeParams().Len() > 0 {
 		check.errorf(x, _Todo, "cannot use generic function %s without instantiation in %s", x, context)
 	}
 

src/go/types/builtins.go

@@ -299,7 +299,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// (applyTypeFunc never calls f with a type parameter)
 		f := func(typ Type) Type {
 			assert(asTypeParam(typ) == nil)
-			if t := toBasic(typ); t != nil {
+			if t := asBasic(typ); t != nil {
 				switch t.kind {
 				case Float32:
 					return Typ[Complex64]
@@ -423,7 +423,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// (applyTypeFunc never calls f with a type parameter)
 		f := func(typ Type) Type {
 			assert(asTypeParam(typ) == nil)
-			if t := toBasic(typ); t != nil {
+			if t := asBasic(typ); t != nil {
 				switch t.kind {
 				case Complex64:
 					return Typ[Float32]
@@ -713,7 +713,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 
-		typ := toPointer(x.typ)
+		typ := asPointer(x.typ)
 		if typ == nil {
 			check.invalidArg(x, _InvalidUnsafeSlice, "%s is not a pointer", x)
 			return
@@ -893,7 +893,7 @@ func makeSig(res Type, args ...Type) *Signature {
 // otherwise it returns typ.
 func arrayPtrDeref(typ Type) Type {
 	if p, ok := typ.(*Pointer); ok {
-		if a := toArray(p.base); a != nil {
+		if a := asArray(p.base); a != nil {
 			return a
 		}
 	}

src/go/types/call.go

@@ -141,7 +141,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 					check.errorf(call.Args[0], _BadDotDotDotSyntax, "invalid use of ... in conversion to %s", T)
 					break
 				}
-				if t := toInterface(T); t != nil {
+				if t := asInterface(T); t != nil {
 					if !t.IsMethodSet() {
 						check.errorf(call, _Todo, "cannot use interface %s in conversion (contains specific type constraints or is comparable)", T)
 						break

src/go/types/conversions.go

@@ -21,7 +21,7 @@ func (check *Checker) conversion(x *operand, T Type) {
 	switch {
 	case constArg && isConstType(T):
 		// constant conversion (T cannot be a type parameter)
-		switch t := toBasic(T); {
+		switch t := asBasic(T); {
 		case representableConst(x.val, check, t, &x.val):
 			ok = true
 		case isInteger(x.typ) && isString(t):
@@ -198,9 +198,9 @@ func convertibleToImpl(check *Checker, V, T Type, cause *string) bool {
 
 	// "V is a slice, T is a pointer-to-array type,
 	// and the slice and array types have identical element types."
-	if s := toSlice(V); s != nil {
-		if p := toPointer(T); p != nil {
-			if a := toArray(p.Elem()); a != nil {
+	if s := asSlice(V); s != nil {
+		if p := asPointer(T); p != nil {
+			if a := asArray(p.Elem()); a != nil {
 				if Identical(s.Elem(), a.Elem()) {
 					if check == nil || check.allowVersion(check.pkg, 1, 17) {
 						return true
@@ -221,26 +221,26 @@ func convertibleToImpl(check *Checker, V, T Type, cause *string) bool {
 // use the toT convenience converters in the predicates below.
 
 func isUintptr(typ Type) bool {
-	t := toBasic(typ)
+	t := asBasic(typ)
 	return t != nil && t.kind == Uintptr
 }
 
 func isUnsafePointer(typ Type) bool {
-	// TODO(gri): Is this toBasic(typ) instead of typ.(*Basic) correct?
+	// TODO(gri): Is this asBasic(typ) instead of typ.(*Basic) correct?
 	//            (The former calls under(), while the latter doesn't.)
 	//            The spec does not say so, but gc claims it is. See also
 	//            issue 6326.
-	t := toBasic(typ)
+	t := asBasic(typ)
 	return t != nil && t.kind == UnsafePointer
 }
 
 func isPointer(typ Type) bool {
-	return toPointer(typ) != nil
+	return asPointer(typ) != nil
 }
 
 func isBytesOrRunes(typ Type) bool {
-	if s := toSlice(typ); s != nil {
-		t := toBasic(s.elem)
+	if s := asSlice(typ); s != nil {
+		t := asBasic(s.elem)
 		return t != nil && (t.kind == Byte || t.kind == Rune)
 	}
 	return false

src/go/types/expr.go

@@ -103,7 +103,7 @@ func (check *Checker) overflow(x *operand, op token.Token, opPos token.Pos) {
 	// x.typ cannot be a type parameter (type
 	// parameters cannot be constant types).
 	if isTyped(x.typ) {
-		check.representable(x, toBasic(x.typ))
+		check.representable(x, asBasic(x.typ))
 		return
 	}
 
@@ -556,7 +556,7 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 	// If the new type is not final and still untyped, just
 	// update the recorded type.
 	if !final && isUntyped(typ) {
-		old.typ = toBasic(typ)
+		old.typ = asBasic(typ)
 		check.untyped[x] = old
 		return
 	}
@@ -1355,7 +1355,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 					duplicate := false
 					// if the key is of interface type, the type is also significant when checking for duplicates
 					xkey := keyVal(x.val)
-					if toInterface(utyp.key) != nil {
+					if asInterface(utyp.key) != nil {
 						for _, vtyp := range visited[xkey] {
 							if Identical(vtyp, x.typ) {
 								duplicate = true

src/go/types/index.go

@@ -35,7 +35,7 @@ func (check *Checker) indexExpr(x *operand, e *typeparams.IndexExpr) (isFuncInst
 		return false
 
 	case value:
-		if sig := toSignature(x.typ); sig != nil && sig.TypeParams().Len() > 0 {
+		if sig := asSignature(x.typ); sig != nil && sig.TypeParams().Len() > 0 {
 			// function instantiation
 			return true
 		}
@@ -72,7 +72,7 @@ func (check *Checker) indexExpr(x *operand, e *typeparams.IndexExpr) (isFuncInst
 		x.typ = typ.elem
 
 	case *Pointer:
-		if typ := toArray(typ.base); typ != nil {
+		if typ := asArray(typ.base); typ != nil {
 			valid = true
 			length = typ.len
 			x.mode = variable
@@ -242,7 +242,7 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 		x.typ = &Slice{elem: u.elem}
 
 	case *Pointer:
-		if u := toArray(u.base); u != nil {
+		if u := asArray(u.base); u != nil {
 			valid = true
 			length = u.len
 			x.typ = &Slice{elem: u.elem}

src/go/types/lookup.go

@@ -302,7 +302,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		return
 	}
 
-	if ityp := toInterface(V); ityp != nil {
+	if ityp := asInterface(V); ityp != nil {
 		// TODO(gri) the methods are sorted - could do this more efficiently
 		for _, m := range T.typeSet().methods {
 			_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
@@ -400,7 +400,7 @@ func (check *Checker) assertableTo(V *Interface, T Type) (method, wrongType *Fun
 	// no static check is required if T is an interface
 	// spec: "If T is an interface type, x.(T) asserts that the
 	//        dynamic type of x implements the interface T."
-	if toInterface(T) != nil && !forceStrict {
+	if asInterface(T) != nil && !forceStrict {
 		return
 	}
 	return check.missingMethod(T, V, false)
@@ -418,8 +418,8 @@ func deref(typ Type) (Type, bool) {
 // derefStructPtr dereferences typ if it is a (named or unnamed) pointer to a
 // (named or unnamed) struct and returns its base. Otherwise it returns typ.
 func derefStructPtr(typ Type) Type {
-	if p := toPointer(typ); p != nil {
-		if toStruct(p.base) != nil {
+	if p := asPointer(typ); p != nil {
+		if asStruct(p.base) != nil {
 			return p.base
 		}
 	}

src/go/types/predicates.go

@@ -58,7 +58,7 @@ func isNumericOrString(typ Type) bool { return is(typ, IsNumeric|IsString) }
 // are not fully set up.
 func isTyped(typ Type) bool {
 	// isTyped is called with types that are not fully
-	// set up. Must not call toBasic()!
+	// set up. Must not call asBasic()!
 	t, _ := typ.(*Basic)
 	return t == nil || t.info&IsUntyped == 0
 }
@@ -72,13 +72,13 @@ func isOrdered(typ Type) bool { return is(typ, IsOrdered) }
 
 func isConstType(typ Type) bool {
 	// Type parameters are never const types.
-	t := toBasic(typ)
+	t := asBasic(typ)
 	return t != nil && t.info&IsConstType != 0
 }
 
 // IsInterface reports whether typ is an interface type.
 func IsInterface(typ Type) bool {
-	return toInterface(typ) != nil
+	return asInterface(typ) != nil
 }
 
 // Comparable reports whether values of type T are comparable.

src/go/types/sizes.go

@@ -243,7 +243,7 @@ func (conf *Config) offsetsof(T *Struct) []int64 {
 func (conf *Config) offsetof(typ Type, index []int) int64 {
 	var o int64
 	for _, i := range index {
-		s := toStruct(typ)
+		s := asStruct(typ)
 		o += conf.offsetsof(s)[i]
 		typ = s.fields[i].typ
 	}

src/go/types/type.go

@@ -29,37 +29,37 @@ func under(t Type) Type {
 
 // Convenience converters
 
-func toBasic(t Type) *Basic {
+func asBasic(t Type) *Basic {
 	op, _ := under(t).(*Basic)
 	return op
 }
 
-func toArray(t Type) *Array {
+func asArray(t Type) *Array {
 	op, _ := under(t).(*Array)
 	return op
 }
 
-func toSlice(t Type) *Slice {
+func asSlice(t Type) *Slice {
 	op, _ := under(t).(*Slice)
 	return op
 }
 
-func toStruct(t Type) *Struct {
+func asStruct(t Type) *Struct {
 	op, _ := under(t).(*Struct)
 	return op
 }
 
-func toPointer(t Type) *Pointer {
+func asPointer(t Type) *Pointer {
 	op, _ := under(t).(*Pointer)
 	return op
 }
 
-func toSignature(t Type) *Signature {
+func asSignature(t Type) *Signature {
 	op, _ := under(t).(*Signature)
 	return op
 }
 
-func toInterface(t Type) *Interface {
+func asInterface(t Type) *Interface {
 	op, _ := under(t).(*Interface)
 	return op
 }

src/go/types/typestring.go

@@ -366,7 +366,7 @@ func (w *typeWriter) tuple(tup *Tuple, variadic bool) {
 				} else {
 					// special case:
 					// append(s, "foo"...) leads to signature func([]byte, string...)
-					if t := toBasic(typ); t == nil || t.kind != String {
+					if t := asBasic(typ); t == nil || t.kind != String {
 						w.error("expected string type")
 						continue
 					}

src/go/types/typexpr.go

@@ -145,7 +145,7 @@ func (check *Checker) varType(e ast.Expr) Type {
 	// are in the middle of type-checking parameter declarations that might belong to
 	// interface methods. Delay this check to the end of type-checking.
 	check.later(func() {
-		if t := toInterface(typ); t != nil {
+		if t := asInterface(typ); t != nil {
 			tset := computeInterfaceTypeSet(check, e.Pos(), t) // TODO(gri) is this the correct position?
 			if !tset.IsMethodSet() {
 				if tset.comparable {