From 38d8bcfa38af6494a92557425458dc19a8e204d4 Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Thu, 23 May 2019 12:08:20 -0400
Subject: [PATCH] internal/lsp: don't show diagnostics for mod files

The Go file changes didn't actually check the file extensions for the
files the Go extension is receiving. This error was not noticed because
the VSCode extension doesn't yet actually send mod files to gopls yet,
but it will in its next release.

Fixes golang/go#32178

Change-Id: Ia04d0a92ce7df13fcf4c601421bc000d69855f6d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/178679
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
---
 internal/lsp/cache/check.go        |  8 +-------
 internal/lsp/cache/view.go         | 21 ++++++++++++++++-----
 internal/lsp/source/diagnostics.go |  3 ++-
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/internal/lsp/cache/check.go b/internal/lsp/cache/check.go
index 67b92566..24933a5b 100644
--- a/internal/lsp/cache/check.go
+++ b/internal/lsp/cache/check.go
@@ -15,11 +15,10 @@ import (
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/packages"
-	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
 )
 
-func (v *view) parse(ctx context.Context, file source.File) ([]packages.Error, error) {
+func (v *view) parse(ctx context.Context, f *goFile) ([]packages.Error, error) {
 	v.mcache.mu.Lock()
 	defer v.mcache.mu.Unlock()
 
@@ -28,11 +27,6 @@ func (v *view) parse(ctx context.Context, file source.File) ([]packages.Error, e
 		return nil, err
 	}
 
-	f, ok := file.(*goFile)
-	if !ok {
-		return nil, fmt.Errorf("not a go file: %v", file.URI())
-	}
-
 	// If the package for the file has not been invalidated by the application
 	// of the pending changes, there is no need to continue.
 	if f.isPopulated() {
diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index f2573605..1cf37d0f 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -6,10 +6,12 @@ package cache
 
 import (
 	"context"
+	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/types"
 	"os"
+	"path/filepath"
 	"sync"
 
 	"golang.org/x/tools/go/packages"
@@ -327,12 +329,21 @@ func (v *view) getFile(uri span.URI) (viewFile, error) {
 	if err != nil {
 		return nil, err
 	}
-	f := &goFile{
-		fileBase: fileBase{
-			view:  v,
-			fname: filename,
-		},
+	var f *goFile
+	switch ext := filepath.Ext(filename); ext {
+	case ".go":
+		f = &goFile{
+			fileBase: fileBase{
+				view:  v,
+				fname: filename,
+			},
+		}
+	case ".mod":
+		return nil, fmt.Errorf("mod files are not yet supported")
+	default:
+		return nil, fmt.Errorf("unsupported file extension: %s", ext)
 	}
+
 	v.mapFile(uri, f)
 	return f, nil
 }
diff --git a/internal/lsp/source/diagnostics.go b/internal/lsp/source/diagnostics.go
index 5cbea3cc..2b4757ca 100644
--- a/internal/lsp/source/diagnostics.go
+++ b/internal/lsp/source/diagnostics.go
@@ -56,9 +56,10 @@ func Diagnostics(ctx context.Context, v View, uri span.URI) (map[span.URI][]Diag
 	if err != nil {
 		return singleDiagnostic(uri, "no file found for %s", uri), nil
 	}
+	// For non-Go files, don't return any diagnostics.
 	gof, ok := f.(GoFile)
 	if !ok {
-		return singleDiagnostic(uri, "%s is not a go file", uri), nil
+		return nil, nil
 	}
 	pkg := gof.GetPackage(ctx)
 	if pkg == nil {