internal/refactor/inline: don't add same import PkgName twice

The logic to choose a fresh names checked for conflicts
in the caller and callee but not against the newly added
imports. This change adds a fix and a test.

Also, don't use "init" as a PkgName: it's reserved.

Fixes golang/go#63298

Change-Id: I7670fb841d6a4f521d567d39fef86c88f06e5c98
Reviewed-on: https://go-review.googlesource.com/c/tools/+/531698
Reviewed-by: Robert Findley <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: adonovan

internal/refactor/inline/inline.go

@@ -331,18 +331,29 @@ func inline(logf func(string, ...any), caller *Caller, callee *gobCallee) (*resu
 			}
 		}
 
+		newlyAdded := func(name string) bool {
+			for _, new := range newImports {
+				if new.Name.Name == name {
+					return true
+				}
+			}
+			return false
+		}
+
 		// import added by callee
 		//
 		// Choose local PkgName based on last segment of
 		// package path plus, if needed, a numeric suffix to
 		// ensure uniqueness.
 		//
+		// "init" is not a legal PkgName.
+		//
 		// TODO(adonovan): preserve the PkgName used
 		// in the original source, or, for a dot import,
 		// use the package's declared name.
 		base := pathpkg.Base(path)
 		name := base
-		for n := 0; shadows[name] || caller.lookup(name) != nil; n++ {
+		for n := 0; shadows[name] || caller.lookup(name) != nil || newlyAdded(name) || name == "init"; n++ {
 			name = fmt.Sprintf("%s%d", base, n)
 		}
 

internal/refactor/inline/testdata/issue63298.txtar

@@ -0,0 +1,52 @@
+Regression test for #63298: inlining a function that
+depends on two packages with the same name leads
+to duplicate PkgNames.
+
+-- go.mod --
+module testdata
+go 1.12
+
+-- a/a.go --
+package a
+
+func _() {
+	a2() //@ inline(re"a2", result)
+}
+
+-- a/a2.go --
+package a
+
+import "testdata/b"
+import anotherb "testdata/another/b"
+
+func a2() {
+	b.B()
+	anotherb.B()
+}
+
+-- b/b.go --
+package b
+
+func B() {}
+
+-- b/another/b.go --
+package b
+
+func B() {}
+
+-- result --
+package a
+
+import (
+	b "testdata/b"
+	b0 "testdata/another/b"
+
+	//@ inline(re"a2", result)
+)
+
+func _() {
+	{
+		b.B()
+		b0.B()
+	}
+}