Makefile: enforce formatting of sys files in presubmit

Makefile

@@ -10,6 +10,7 @@ endif
 	manager fuzzer executor \
 	ci hub \
 	execprog mutate prog2c stress repro upgrade db \
+	bin/syz-sysgen bin/syz-extract bin/syz-fmt \
 	extract generate \
 	android \
 	format tidy test arch presubmit clean
@@ -81,9 +82,12 @@ generate: bin/syz-sysgen
 bin/syz-sysgen:
 	go build $(GOFLAGS) -o $@ ./sys/syz-sysgen
 
-format:
+format: bin/syz-fmt
 	go fmt ./...
 	clang-format --style=file -i executor/*.cc executor/*.h tools/kcovtrace/*.c
+	bin/syz-fmt sys
+bin/syz-fmt:
+	go build $(GOFLAGS) -o $@ ./tools/syz-fmt
 
 tidy:
 	# A single check is enabled for now. But it's always fixable and proved to be useful.

pkg/ast/parser_test.go

@@ -42,12 +42,10 @@ func TestParseAll(t *testing.T) {
 		if len(top) != len(top2) {
 			t.Fatalf("formatting number of top level decls: %v/%v", len(top), len(top2))
 		}
-		if false {
-			// While sys files are not formatted, formatting in fact changes it.
-			for i := range top {
-				if !reflect.DeepEqual(top[i], top2[i]) {
-					t.Fatalf("formatting changed code:\n%#v\nvs:\n%#v", top[i], top2[i])
-				}
+		// While sys files are not formatted, formatting in fact changes it.
+		for i := range top {
+			if !reflect.DeepEqual(top[i], top2[i]) {
+				t.Fatalf("formatting changed code:\n%#v\nvs:\n%#v", top[i], top2[i])
 			}
 		}
 	}

tools/syz-fmt/syz-fmt.go

@@ -61,6 +61,7 @@ func processFile(file string, mode os.FileMode) {
 	if bytes.Equal(data, formatted) {
 		return
 	}
+	fmt.Printf("reformatting %v\n", file)
 	if err := os.Rename(file, file+"~"); err != nil {
 		fmt.Fprintf(os.Stderr, "%v\n", err)
 		os.Exit(1)