cmd/compile: fix importing rewritten f(g()) calls

golang.org/cl/166983 started serializing the Ninit field of OCALL
nodes within function inline bodies (necessary to fix a regression in
building crypto/ecdsa with -gcflags=-l=4), but this means the Ninit
field needs to be typechecked when the imported function body is used.

It's unclear why this wasn't necessary for the crypto/ecdsa
regression.

Fixes #30907.

Change-Id: Id5f0bf3c4d17bbd6d5318913b859093c93a0a20c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168199
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/typecheck.go

@@ -1239,6 +1239,7 @@ func typecheck1(n *Node, top int) (res *Node) {
 
 	// call and call like
 	case OCALL:
+		typecheckslice(n.Ninit.Slice(), ctxStmt) // imported rewritten f(g()) calls (#30907)
 		n.Left = typecheck(n.Left, ctxExpr|Etype|ctxCallee)
 		if n.Left.Diag() {
 			n.SetDiag(true)

test/fixedbugs/issue30907.dir/a.go

@@ -0,0 +1,19 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type UUID string
+
+func New() UUID {
+	return Must(NewRandom())
+}
+
+func NewRandom() (UUID, error) {
+	return "", nil
+}
+
+func Must(uuid UUID, err error) UUID {
+	return uuid
+}

test/fixedbugs/issue30907.dir/b.go

@@ -0,0 +1,11 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+import "./a"
+
+func F() {
+	a.New()
+}

test/fixedbugs/issue30907.go

@@ -0,0 +1,7 @@
+// compiledir
+
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored