runtime: block signal_recv on targets without signal delivery (#5619)

main_test.go

@@ -81,6 +81,7 @@ func TestBuild(t *testing.T) {
 		"print.go",
 		"reflect.go",
 		"signal.go",
+		"signalnotify.go",
 		"slice.go",
 		"sort.go",
 		"stdlib.go",
@@ -440,7 +441,14 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 				continue
 			}
 		}
-		if isWebAssembly || isBaremetal || options.GOOS == "windows" {
+		if options.GOOS == "windows" {
+			switch name {
+			case "signal.go", "signalnotify.go":
+				// os/signal does not link on Windows.
+				continue
+			}
+		}
+		if isWebAssembly || isBaremetal {
 			switch name {
 			case "signal.go":
 				// Signals only work on POSIX-like systems.

src/runtime/signalstub.go

@@ -18,4 +18,9 @@ func signal_ignore(uint32) {}
 func signal_waitUntilIdle() {}
 
 //go:linkname signal_recv os/signal.signal_recv
-func signal_recv() uint32 { return ^uint32(0) }
+func signal_recv() uint32 {
+	// Block to prevent os/signal.loop from running continuously.
+	// See https://go.dev/src/os/signal/signal_unix.go.
+	deadlock()
+	return 0
+}

testdata/signalnotify.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"os"
+	"os/signal"
+	"time"
+)
+
+func main() {
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	time.Sleep(10 * time.Millisecond)
+	println("done")
+}

testdata/signalnotify.txt

@@ -0,0 +1 @@
+done