gopls: initial support for godebug directive in go.mod and go.work

For now, incorporate godebug support by just updating x/mod and write
some tests. Diagnostics are mispositioned due to golang/go#67623.

While writing tests, I realized that the expect package still did not
support go.work files. Add this missing support. Also, remove a stale
comment from go.mod comment extraction, and simplify.

Fixes golang/go#67583

Change-Id: I9d9bb53824b8c817ee18f51a0cfca63842565513
Reviewed-on: https://go-review.googlesource.com/c/tools/+/588055
Reviewed-by: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: findleyr

go/expect/expect.go

@@ -4,7 +4,7 @@
 
 /*
 Package expect provides support for interpreting structured comments in Go
-source code as test expectations.
+source code (including go.mod and go.work files) as test expectations.
 
 This is primarily intended for writing tests of things that process Go source
 files, although it does not directly depend on the testing package.

go/expect/expect_test.go

@@ -50,6 +50,14 @@ func TestMarker(t *testing.T) {
 				"βMarker": "require golang.org/modfile v0.0.0",
 			},
 		},
+		{
+			filename:    "testdata/go.fake.work",
+			expectNotes: 2,
+			expectMarkers: map[string]string{
+				"αMarker": "1.23.0",
+				"βMarker": "αβ",
+			},
+		},
 	} {
 		t.Run(tt.filename, func(t *testing.T) {
 			content, err := os.ReadFile(tt.filename)

go/expect/extract.go

@@ -54,7 +54,7 @@ func Parse(fset *token.FileSet, filename string, content []byte) ([]*Note, error
 		}
 		f := fset.AddFile(filename, -1, len(content))
 		f.SetLinesForContent(content)
-		notes, err := extractMod(fset, file)
+		notes, err := extractModWork(fset, file.Syntax.Stmt)
 		if err != nil {
 			return nil, err
 		}
@@ -64,39 +64,45 @@ func Parse(fset *token.FileSet, filename string, content []byte) ([]*Note, error
 			note.Pos += token.Pos(f.Base())
 		}
 		return notes, nil
+	case ".work":
+		file, err := modfile.ParseWork(filename, content, nil)
+		if err != nil {
+			return nil, err
+		}
+		f := fset.AddFile(filename, -1, len(content))
+		f.SetLinesForContent(content)
+		notes, err := extractModWork(fset, file.Syntax.Stmt)
+		if err != nil {
+			return nil, err
+		}
+		// As with go.mod files, we need to compute a synthetic token.Pos.
+		for _, note := range notes {
+			note.Pos += token.Pos(f.Base())
+		}
+		return notes, nil
 	}
 	return nil, nil
 }
 
-// extractMod collects all the notes present in a go.mod file.
+// extractModWork collects all the notes present in a go.mod file or go.work
+// file, by way of the shared modfile.Expr statement node.
+//
 // Each comment whose text starts with @ is parsed as a comma-separated
 // sequence of notes.
 // See the package documentation for details about the syntax of those
 // notes.
 // Only allow notes to appear with the following format: "//@mark()" or // @mark()
-func extractMod(fset *token.FileSet, file *modfile.File) ([]*Note, error) {
+func extractModWork(fset *token.FileSet, exprs []modfile.Expr) ([]*Note, error) {
 	var notes []*Note
-	for _, stmt := range file.Syntax.Stmt {
+	for _, stmt := range exprs {
 		comment := stmt.Comment()
 		if comment == nil {
 			continue
 		}
-		// Handle the case for markers of `// indirect` to be on the line before
-		// the require statement.
-		// TODO(golang/go#36894): have a more intuitive approach for // indirect
-		for _, cmt := range comment.Before {
-			text, adjust := getAdjustedNote(cmt.Token)
-			if text == "" {
-				continue
-			}
-			parsed, err := parse(fset, token.Pos(int(cmt.Start.Byte)+adjust), text)
-			if err != nil {
-				return nil, err
-			}
-			notes = append(notes, parsed...)
-		}
-		// Handle the normal case for markers on the same line.
-		for _, cmt := range comment.Suffix {
+		var allComments []modfile.Comment
+		allComments = append(allComments, comment.Before...)
+		allComments = append(allComments, comment.Suffix...)
+		for _, cmt := range allComments {
 			text, adjust := getAdjustedNote(cmt.Token)
 			if text == "" {
 				continue

go/expect/testdata/go.fake.work

@@ -0,0 +1,7 @@
+// This file is named go.fake.mod so it does not define a real module, which
+// would make the contents of this directory unavailable to the test when run
+// from outside the repository.
+
+go 1.23.0 //@mark(αMarker, "1.23.0")
+
+use ./αβ //@mark(βMarker, "αβ")

gopls/go.mod

@@ -5,7 +5,7 @@ go 1.19 // => default GODEBUG has gotypesalias=0
 require (
 	github.com/google/go-cmp v0.6.0
 	github.com/jba/templatecheck v0.7.0
-	golang.org/x/mod v0.17.0
+	golang.org/x/mod v0.17.1-0.20240514174713-c0bdc7bd01c9
 	golang.org/x/sync v0.7.0
 	golang.org/x/telemetry v0.0.0-20240521205824-bda55230c457
 	golang.org/x/text v0.15.0

gopls/go.sum

@@ -16,8 +16,9 @@ golang.org/x/crypto v0.23.0/go.mod h1:CKFgDieR+mRhux2Lsu27y0fO304Db0wZe70UKqHu0v
 golang.org/x/exp/typeparams v0.0.0-20221212164502-fae10dda9338 h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y=
 golang.org/x/exp/typeparams v0.0.0-20221212164502-fae10dda9338/go.mod h1:AbB0pIl9nAr9wVwH+Z2ZpaocVmF5I4GyWCDIsVjR0bk=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-golang.org/x/mod v0.17.0 h1:zY54UmvipHiNd+pm+m0x9KhZ9hl1/7QNMyxXbc6ICqA=
 golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/mod v0.17.1-0.20240514174713-c0bdc7bd01c9 h1:EfMABMgrJ8+hRjLvhUzJkLKgFv3lYAglGXczg5ggNyk=
+golang.org/x/mod v0.17.1-0.20240514174713-c0bdc7bd01c9/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=

gopls/internal/test/marker/testdata/modfile/godebug.txt

@@ -0,0 +1,43 @@
+This test basic gopls functionality in a workspace with a godebug
+directive in its modfile.
+
+-- flags --
+-min_go=go1.23
+
+-- go.mod --
+module example.com/m
+
+go 1.23
+
+godebug (
+	gotypesalias=0
+)
+godebug gotypesalias=1
+
+-- a/a.go --
+package a
+
+import "example.com/m/b"
+
+const A = b.B //@def("B", B)
+
+-- b/b.go --
+package b
+
+const B = 42 //@loc(B, "B")
+
+-- format/go.mod --
+module example.com/m/format //@format(formatted)
+
+godebug (
+gotypesalias=0
+)
+godebug      gotypesalias=1
+-- @formatted --
+module example.com/m/format //@format(formatted)
+
+godebug (
+	gotypesalias=0
+)
+
+godebug gotypesalias=1

gopls/internal/test/marker/testdata/modfile/godebug_bad.txt

@@ -0,0 +1,17 @@
+This test checks that we surface the error for unexpected godebug values.
+
+TODO(golang/go#67623): the diagnostic should be on the bad godebug value.
+
+-- flags --
+-min_go=go1.23
+-errors_ok
+
+-- go.mod --
+module example.com/m //@diag("module", re`unknown godebug "gotypealias"`)
+
+go 1.23
+
+godebug (
+	gotypealias=0 // misspelled
+)
+godebug gotypesalias=1

gopls/internal/test/marker/testdata/workfile/godebug.txt

@@ -0,0 +1,60 @@
+This test basic gopls functionality in a workspace with a godebug
+directive in its modfile.
+
+-- flags --
+-min_go=go1.23
+
+-- a/go.work --
+go 1.23
+
+use .
+
+godebug (
+	gotypesalias=0
+)
+godebug gotypesalias=1
+
+-- a/go.mod --
+module example.com/a
+
+go 1.23
+
+-- a/a.go --
+package a
+
+import "example.com/a/b"
+
+const A = b.B //@def("B", B)
+
+-- a/b/b.go --
+package b
+
+const B = 42 //@loc(B, "B")
+
+-- format/go.work --
+go 1.23 //@format(formatted)
+
+use .
+
+godebug (
+gotypesalias=0
+)
+godebug     gotypesalias=1
+
+-- @formatted --
+go 1.23 //@format(formatted)
+
+use .
+
+godebug (
+	gotypesalias=0
+)
+
+godebug gotypesalias=1
+-- format/go.mod --
+module example.com/format
+
+go 1.23
+
+-- format/p.go --
+package format

gopls/internal/test/marker/testdata/workfile/godebug_bad.txt

@@ -0,0 +1,22 @@
+This test checks that we surface the error for unexpected godebug values.
+
+TODO(golang/go#67623): the diagnostic should be on the bad godebug value.
+
+-- flags --
+-min_go=go1.23
+-errors_ok
+
+-- go.work --
+go 1.23
+
+use .
+
+godebug (
+	gotypealias=0 // misspelled
+)
+godebug gotypesalias=1
+
+-- go.mod --
+module example.com/m //@diag("module", re`unknown godebug "gotypealias"`)
+
+go 1.23