cmd/compile: fix width not calculated for imported type

The compiler currently has problem that some imported type is missing
size calculation. The problem is not triggered until CL 283313 merged,
due to the compiler can compile the functions immediately when it sees
them, so during SSA generation, size calculation is still ok.

CL 283313 makes the compiler always push functions to compile queue,
then drain from it for compiling function. During this process, the
types calculation size is disabled, so calculating size during SSA now
make the compiler crashes.

To fix this, we can just always calculate type size during typechecking,
when importing type from other packages.

Fixes #44732

Change-Id: I8d00ea0b5aadd432154908280e55d85c75f3ce92
Reviewed-on: https://go-review.googlesource.com/c/go/+/299689
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -508,6 +508,12 @@ func (p *iimporter) typAt(off uint64) *types.Type {
 			base.Fatalf("predeclared type missing from cache: %d", off)
 		}
 		t = p.newReader(off-predeclReserved, nil).typ1()
+		// Ensure size is calculated for imported types. Since CL 283313, the compiler
+		// does not compile the function immediately when it sees them. Instead, funtions
+		// are pushed to compile queue, then draining from the queue for compiling.
+		// During this process, the size calculation is disabled, so it is not safe for
+		// calculating size during SSA generation anymore. See issue #44732.
+		types.CheckSize(t)
 		p.typCache[off] = t
 	}
 	return t

test/fixedbugs/issue44732.dir/bar/bar.go

@@ -0,0 +1,11 @@
+// Copyright 2021 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 bar
+
+import "issue44732.dir/foo"
+
+type Bar struct {
+	Foo *foo.Foo
+}

test/fixedbugs/issue44732.dir/foo/foo.go

@@ -0,0 +1,13 @@
+// Copyright 2021 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 foo
+
+type Foo struct {
+	updatecb func()
+}
+
+func NewFoo() *Foo {
+	return &Foo{updatecb: nil}
+}

test/fixedbugs/issue44732.dir/main.go

@@ -0,0 +1,15 @@
+// Copyright 2021 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 main
+
+import (
+	"issue44732.dir/bar"
+	"issue44732.dir/foo"
+)
+
+func main() {
+	_ = bar.Bar{}
+	_ = foo.NewFoo()
+}

test/fixedbugs/issue44732.go

@@ -0,0 +1,7 @@
+// runindir
+
+// Copyright 2021 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