cmd/compile: restrict //go:notinheap to runtime/internal/sys

So it won't be visible outside of runtime package. There are changes to
make tests happy:

 - For test/directive*.go files, using "go:noinline" for testing misplaced
 directives instead.
 - Restrict test/fixedbugs/bug515.go for gccgo only.
 - For test/notinheap{2,3}.go, using runtime/cgo.Incomplete for marking
 the type as not-in-heap. Though it's somewhat clumsy, it's the easiest
 way to keep the test errors for not-in-heap types until we can cleanup
 further.
 - test/typeparam/mdempsky/11.go is about defined type in user code marked
 as go:notinheap, which can't happen after this CL, though.

Fixes #46731

Change-Id: I869f5b2230c8a2a363feeec042e7723bbc416e8e
Reviewed-on: https://go-review.googlesource.com/c/go/+/421882
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Joedian Reid <joedian@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/test/fixedbugs/bug515.go b/test/fixedbugs/bug515.go
index 186f46609a..80d426fd67 100644
--- a/test/fixedbugs/bug515.go
+++ b/test/fixedbugs/bug515.go
@@ -6,16 +6,18 @@
 
 // Caused a gofrontend crash.
 
+//go:build gccgo
+
 package p
 
 //go:notinheap
 type S1 struct{}
 
 type S2 struct {
-	r interface { Read([]byte) (int, error) }
+	r      interface{ Read([]byte) (int, error) }
 	s1, s2 []byte
-	p *S1
-	n uintptr
+	p      *S1
+	n      uintptr
 }
 
 var V any = S2{}