go/ast: CommentMap mishandles loose, trailing file comments #21755
Comments
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CC @griesemer |
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I also see that there even is a test that includes this: In that case, the trailing comment in the file is attached to an Another option would be to attach it to the whole |
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Closed by mistake in one of @josharian's private repos, I assume. |
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A couple of other weird cases: https://play.golang.org/p/d46URuVRTJ |
ianlancetaylor
added
the
NeedsInvestigation
Indeed. FWIW, here's the diff I used, which fixed it the way I wanted it fixed for my private purposes. I haven't thought about whether it is an appropriate fix for the diff --git a/astutil/commentmap.go b/astutil/commentmap.go
index c6f0d62..7c8170f 100644
--- a/astutil/commentmap.go
+++ b/astutil/commentmap.go
@@ -206,7 +206,8 @@ func NewCommentMap(fset *token.FileSet, node ast.Node, comments []*ast.CommentGr
switch {
case pg != nil &&
(pgend.Line == r.pos.Line ||
- pgend.Line+1 == r.pos.Line && r.end.Line+1 < qpos.Line):
+ pgend.Line+1 == r.pos.Line && r.end.Line+1 < qpos.Line ||
+ q == nil):
// 1) comment starts on same line as previous node group ends, or
// 2) comment starts on the line immediately after the
// previous node group and there is an empty line before
diff --git a/astutil/commentmap_test.go b/astutil/commentmap_test.go
index 3df0e65..a645032 100644
--- a/astutil/commentmap_test.go
+++ b/astutil/commentmap_test.go
@@ -92,9 +92,9 @@ var res = map[string]string{
"31: *ast.ExprStmt": " associated with s1\nalso associated with s1\n",
"37: *ast.ExprStmt": "associated with s2\nalso associated with s2\nline comment for s2\n",
"45: *ast.FuncDecl": "associated with f2\nf2\n",
+ "48: *ast.FuncDecl": "the very last comment\n",
"49: *ast.AssignStmt": "addition\n",
"49: *ast.BasicLit": " 1\n",
- "50: *ast.Ident": "the very last comment\n",
} |
go version devel +812b34efae Mon Sep 4 00:07:33 2017 +0000 linux/amd64Construct a comment map for:
The loose trailing comment is associated in the CommentMap with the
return statement inside f. It should probably be associated with f
instead, and the NewCommentMap docs updated with new rules.
Live proof: https://play.golang.org/p/XCktcSxYl8
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