[tools] refactor/satisfy: fix panic on interface literals

[Madeline Kalil (Gerrit)]

Madeline Kalil submitted the change with unreviewed changes

Unreviewed changes

3 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: refactor/satisfy/find.go
Insertions: 4, Deletions: 5.

@@ -395,11 +395,10 @@
 		f.expr(e.X)
 
 	case *ast.SelectorExpr:
-		if _, ok := f.info.Selections[e]; ok {
-			if tv, ok := f.info.Types[e.X]; ok && tv.IsType() {
-				// If e.X is a type (e.g., e is interface{ m() }.m), don't visit it.
-			} else {
-				f.expr(e.X) // selection
+		if seln, ok := f.info.Selections[e]; ok {
+			// If e.X is a type (e.g., e is interface{ m() }.m), don't visit it.
+			if seln.Kind() != types.MethodExpr {
+				f.expr(e.X)
 			}
 		} else {
 			return f.info.Uses[e.Sel].Type() // qualified identifier
```

Change information

Commit message:

refactor/satisfy: fix panic on interface literals

The inspection of the AST in Find() results in a panic
when you have a method expression of an anonymous
interface, because it does not expect an
interface type literal to appear as an expression.

However, this is valid Go code:

// panics on interface{ m() } after visiting e.X in the SelectorExpr e
var _ = interface{ m() }.m

During the AST traversal, if we encounter a SelectorExpr e
where e.X is a type (like interface{Baz()}), we don't need
to visit e.X.

This also fixes a panic in the printf analyzer,
which uses Find to get interface/implementation relations.
Fixes golang/go#77625

Change-Id: I431b70e2c7e3cc9b2db655e99fdb25c223a1a082

Reviewed-on: https://go-review.googlesource.com/c/tools/+/746701

LUCI-TryBot-Result: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>

Reviewed-by: Mark Freeman <markf...@google.com>

Reviewed-by: Alan Donovan <adon...@google.com>

Files:

• M refactor/satisfy/find.go
• M refactor/satisfy/find_test.go

Change size: S

Delta: 2 files changed, 8 insertions(+), 2 deletions(-)

Branch: refs/heads/master

Submit Requirements:

• Code-Review: +2 by Alan Donovan, +2 by Mark Freeman
• TryBots-Pass: LUCI-TryBot-Result+1 by Go LUCI

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Gerrit

Gerrit-MessageType: merged

Gerrit-Project: tools

Gerrit-Branch: master

Gerrit-Change-Id: I431b70e2c7e3cc9b2db655e99fdb25c223a1a082

Gerrit-Change-Number: 746701

Gerrit-PatchSet: 6

Gerrit-Owner: Madeline Kalil <mka...@google.com>

Gerrit-Reviewer: Alan Donovan <adon...@google.com>

Gerrit-Reviewer: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>

Gerrit-Reviewer: Madeline Kalil <mka...@google.com>

Gerrit-Reviewer: Mark Freeman <markf...@google.com>