gopls/internal/cache/parsego: new test case for fixed syntax

This CL adds a new test case to verify the fixed syntax in
parsego.Parse, which helps us better understand its behavior.

Updates: golang/go#64335
Change-Id: I8bf93e43a1bb67853ca02e32232aef48159295d7
Reviewed-on: https://go-review.googlesource.com/c/tools/+/664095
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>

Author: xieyuschen

gopls/internal/cache/parsego/parse.go

@@ -49,7 +49,7 @@ const (
 // Parse parses a buffer of Go source, repairing the tree if necessary.
 //
 // The provided ctx is used only for logging.
-func Parse(ctx context.Context, fset *token.FileSet, uri protocol.DocumentURI, src []byte, mode parser.Mode, purgeFuncBodies bool) (res *File, fixes []fixType) {
+func Parse(ctx context.Context, fset *token.FileSet, uri protocol.DocumentURI, src []byte, mode parser.Mode, purgeFuncBodies bool) (res *File, fixes []FixType) {
 	if purgeFuncBodies {
 		src = astutil.PurgeFuncBodies(src)
 	}
@@ -147,13 +147,13 @@ func Parse(ctx context.Context, fset *token.FileSet, uri protocol.DocumentURI, s
 //
 // If fixAST returns true, the resulting AST is considered "fixed", meaning
 // positions have been mangled, and type checker errors may not make sense.
-func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []fixType) {
+func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []FixType) {
 	var err error
 	walkASTWithParent(n, func(n, parent ast.Node) bool {
 		switch n := n.(type) {
 		case *ast.BadStmt:
 			if fixDeferOrGoStmt(n, parent, tok, src) {
-				fixes = append(fixes, fixedDeferOrGo)
+				fixes = append(fixes, FixedDeferOrGo)
 				// Recursively fix in our fixed node.
 				moreFixes := fixAST(parent, tok, src)
 				fixes = append(fixes, moreFixes...)
@@ -163,7 +163,7 @@ func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []fixType) {
 			return false
 		case *ast.BadExpr:
 			if fixArrayType(n, parent, tok, src) {
-				fixes = append(fixes, fixedArrayType)
+				fixes = append(fixes, FixedArrayType)
 				// Recursively fix in our fixed node.
 				moreFixes := fixAST(parent, tok, src)
 				fixes = append(fixes, moreFixes...)
@@ -177,7 +177,7 @@ func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []fixType) {
 			//   for i := foo
 			//
 			if fixInitStmt(n, parent, tok, src) {
-				fixes = append(fixes, fixedInit)
+				fixes = append(fixes, FixedInit)
 			}
 			return false
 		case *ast.SelectorExpr:
@@ -186,7 +186,7 @@ func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []fixType) {
 			//   foo.var<> // want to complete to "foo.variance"
 			//
 			if fixPhantomSelector(n, tok, src) {
-				fixes = append(fixes, fixedPhantomSelector)
+				fixes = append(fixes, FixedPhantomSelector)
 			}
 			return true
 
@@ -196,7 +196,7 @@ func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []fixType) {
 				// Adjust closing curly brace of empty switch/select
 				// statements so we can complete inside them.
 				if fixEmptySwitch(n, tok, src) {
-					fixes = append(fixes, fixedEmptySwitch)
+					fixes = append(fixes, FixedEmptySwitch)
 				}
 			}
 
@@ -235,24 +235,24 @@ func walkASTWithParent(n ast.Node, f func(n ast.Node, parent ast.Node) bool) {
 
 // TODO(rfindley): revert this intrumentation once we're certain the crash in
 // #59097 is fixed.
-type fixType int
+type FixType int
 
 const (
-	noFix fixType = iota
-	fixedCurlies
-	fixedDanglingSelector
-	fixedDeferOrGo
-	fixedArrayType
-	fixedInit
-	fixedPhantomSelector
-	fixedEmptySwitch
+	noFix FixType = iota
+	FixedCurlies
+	FixedDanglingSelector
+	FixedDeferOrGo
+	FixedArrayType
+	FixedInit
+	FixedPhantomSelector
+	FixedEmptySwitch
 )
 
 // fixSrc attempts to modify the file's source code to fix certain
 // syntax errors that leave the rest of the file unparsed.
 //
 // fixSrc returns a non-nil result if and only if a fix was applied.
-func fixSrc(f *ast.File, tf *token.File, src []byte) (newSrc []byte, fix fixType) {
+func fixSrc(f *ast.File, tf *token.File, src []byte) (newSrc []byte, fix FixType) {
 	walkASTWithParent(f, func(n, parent ast.Node) bool {
 		if newSrc != nil {
 			return false
@@ -262,12 +262,12 @@ func fixSrc(f *ast.File, tf *token.File, src []byte) (newSrc []byte, fix fixType
 		case *ast.BlockStmt:
 			newSrc = fixMissingCurlies(f, n, parent, tf, src)
 			if newSrc != nil {
-				fix = fixedCurlies
+				fix = FixedCurlies
 			}
 		case *ast.SelectorExpr:
 			newSrc = fixDanglingSelector(n, tf, src)
 			if newSrc != nil {
-				fix = fixedDanglingSelector
+				fix = FixedDanglingSelector
 			}
 		}
 

gopls/internal/cache/parsego/parse_test.go

@@ -6,12 +6,15 @@ package parsego_test
 
 import (
 	"context"
+	"fmt"
 	"go/ast"
 	"go/token"
+	"slices"
 	"testing"
 
 	"golang.org/x/tools/gopls/internal/cache/parsego"
 	"golang.org/x/tools/gopls/internal/util/safetoken"
+	"golang.org/x/tools/internal/analysisinternal"
 	"golang.org/x/tools/internal/tokeninternal"
 )
 
@@ -44,3 +47,87 @@ func _() {
 		return true
 	})
 }
+
+func TestFixGoAndDefer_GoStmt(t *testing.T) {
+	var testCases = []struct {
+		source  string
+		fixes   []parsego.FixType
+		wantFix string
+	}{
+		{source: "g", fixes: nil},
+		{source: "go", fixes: nil},
+		{source: "go a.b(", fixes: nil},
+		{source: "go a.b()", fixes: nil},
+		{source: "go func {", fixes: nil},
+		{
+			source:  "go f",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go f()",
+		},
+		{
+			source:  "go func",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go (func())()",
+		},
+		{
+			source:  "go func {}",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go (func())()",
+		},
+		{
+			source:  "go func {}(",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go (func())()",
+		},
+		{
+			source:  "go func {}()",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go (func())()",
+		},
+		{
+			source:  "go a.",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo, parsego.FixedDanglingSelector, parsego.FixedDeferOrGo},
+			wantFix: "go a._()",
+		},
+		{
+			source:  "go a.b",
+			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
+			wantFix: "go a.b()",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.source, func(t *testing.T) {
+			src := filesrc(tc.source)
+			pgf, fixes := parsego.Parse(context.Background(), token.NewFileSet(), "file://foo.go", src, parsego.Full, false)
+			if !slices.Equal(fixes, tc.fixes) {
+				t.Fatalf("TestFixGoAndDefer_GoStmt(): got %v want %v", fixes, tc.fixes)
+			}
+			fset := tokeninternal.FileSetFor(pgf.Tok)
+			check := func(n ast.Node) bool {
+				if n != nil {
+					posn := safetoken.StartPosition(fset, n.Pos())
+					if !posn.IsValid() {
+						t.Fatalf("invalid position for %T (%v): %v not in [%d, %d]", n, n, n.Pos(), pgf.Tok.Base(), pgf.Tok.Base()+pgf.Tok.Size())
+					}
+					if deferStmt, ok := n.(*ast.GoStmt); ok && tc.fixes != nil {
+						if got, want := fmt.Sprintf("go %s", analysisinternal.Format(fset, deferStmt.Call)), tc.wantFix; got != want {
+							t.Fatalf("TestFixGoAndDefer_GoStmt(): got %v want %v", got, want)
+						}
+					}
+				}
+				return true
+			}
+			ast.Inspect(pgf.File, check)
+		})
+	}
+}
+
+func filesrc(expressions string) []byte {
+	const srcTmpl = `package foo
+
+func _() {
+	%s
+}`
+	return fmt.Appendf(nil, srcTmpl, expressions)
+}