internal/lsp/source: trim file very carefully
Apparently the AST will sometimes give us offsets past the end of the
file. Don't crash when it does.
Fixes golang/go#36610.
Change-Id: I3cfbf8645bfcea94a5d87bca5bef4236d657b2c0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/215119
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/internal/lsp/source/format.go b/internal/lsp/source/format.go
index 6d6dfbf..2149fea 100644
--- a/internal/lsp/source/format.go
+++ b/internal/lsp/source/format.go
@@ -245,8 +245,13 @@
tok := fset.File(f.Pos())
start := firstImport.Pos()
end := lastImport.End()
- if tok.LineCount() > fset.Position(end).Line {
- end = fset.File(f.Pos()).LineStart(fset.Position(lastImport.End()).Line + 1)
+ // The parser will happily feed us nonsense. See golang/go#36610.
+ tokStart, tokEnd := token.Pos(tok.Base()), token.Pos(tok.Base()+tok.Size())
+ if start < tokStart || start > tokEnd || end < tokStart || end > tokEnd {
+ return nil, 0
+ }
+ if nextLine := fset.Position(end).Line + 1; tok.LineCount() >= nextLine {
+ end = fset.File(f.Pos()).LineStart(nextLine)
}
startLineOffset := fset.Position(start).Line - 1 // lines are 1-indexed.
diff --git a/internal/lsp/source/format_test.go b/internal/lsp/source/format_test.go
new file mode 100644
index 0000000..678a672
--- /dev/null
+++ b/internal/lsp/source/format_test.go
@@ -0,0 +1,25 @@
+package source
+
+import (
+ "go/parser"
+ "go/token"
+ "testing"
+)
+
+func TestTrimToImports(t *testing.T) {
+ const input = `package source
+
+import (
+ m
+ "fmt"
+)
+
+func foo() {
+ fmt.Println("hi")
+}
+`
+
+ fs := token.NewFileSet()
+ f, _ := parser.ParseFile(fs, "foo.go", input, parser.ImportsOnly)
+ trimToImports(fs, f, []byte(input))
+}
