internal/refactor/inline: fix condition for splice assignment strategy

In the assign statements strategy, if there are no nontrivial result
conversions, we can replace a call with its result expression regardless
of the AssignStmt.Tok.

For golang/go#70599

Change-Id: Ifa2b615c17d58e3bbc708b9ecf98530858915564
Reviewed-on: https://go-review.googlesource.com/c/tools/+/632937
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

gopls/internal/test/marker/testdata/codeaction/moveparam_issue70599.txt

@@ -1,7 +1,5 @@
-This test reproduces various bugs encountered while bug-bashing on the movement
-refactoring.
-
-TODO(rfindley): fix these bugs.
+This test checks the fixes for bugs encountered while bug-bashing on the
+movement refactoring.
 
 -- go.mod --
 module example.com
@@ -74,8 +72,7 @@ func Short(y, x int) (int, int) { //@codeaction("x", "refactor.rewrite.moveParam
 }
 
 func _() {
-	var x, y int
-	x, y = Short(1, 0)
+	x, y := Short(1, 0)
 	_, _ = x, y
 }
 

internal/refactor/inline/inline.go

@@ -3266,10 +3266,9 @@ func (st *state) assignStmts(callerStmt *ast.AssignStmt, returnOperands []ast.Ex
 	//
 	// This works as long as we don't need to write any additional type
 	// information.
-	if callerStmt.Tok == token.ASSIGN && // LHS types already determined before call
-		len(nonTrivial) == 0 { // no non-trivial conversions to worry about
+	if len(nonTrivial) == 0 { // no non-trivial conversions to worry about
 
-		logf("substrategy: slice assignment")
+		logf("substrategy: splice assignment")
 		return []ast.Stmt{&ast.AssignStmt{
 			Lhs:    lhs,
 			Tok:    callerStmt.Tok,

internal/refactor/inline/testdata/assignment-splice.txtar

@@ -0,0 +1,62 @@
+This test checks the splice assignment substrategy.
+
+-- go.mod --
+module testdata
+
+go 1.20
+
+-- a.go --
+package a
+
+func a() (int32, string) {
+	return b()
+}
+
+func b() (int32, string) {
+	return 0, "a"
+}
+
+func c() (int, chan<- int) {
+	return 0, make(chan int) // nontrivial conversion
+}
+
+-- a1.go --
+package a
+
+func _() {
+	x, y := a() //@ inline(re"a", a1)
+}
+-- a1 --
+package a
+
+func _() {
+	x, y := b() //@ inline(re"a", a1)
+}
+-- a2.go --
+package a
+
+func _() {
+	var x, y any
+	x, y = a() //@ inline(re"a", a2)
+}
+-- a2 --
+package a
+
+func _() {
+	var x, y any
+	x, y = b() //@ inline(re"a", a2)
+}
+-- a3.go --
+package a
+
+func _() {
+	var y chan<- int
+	x, y := c() //@ inline(re"c", a3)
+}
+-- a3 --
+package a
+
+func _() {
+	var y chan<- int
+	x, y := 0, make(chan int) //@ inline(re"c", a3)
+}

internal/refactor/inline/testdata/assignment.txtar

@@ -2,7 +2,8 @@ Basic tests of inlining a call on the RHS of an assignment.
 
 -- go.mod --
 module testdata
-go 1.12
+
+go 1.20
 
 -- a/a1.go --
 package a
@@ -104,13 +105,11 @@ package a
 
 import (
 	"testdata/b"
-	"testdata/c"
 )
 
 func _() {
 	var y int
-	var x c.C
-	x, y = b.B1() //@ inline(re"B", b2)
+	x, y := b.B1() //@ inline(re"B", b2)
 	_, _ = x, y
 }
 -- b3 --