gc: remove func, map compare

R=ken, ken
CC=golang-dev
https://golang.org/cl/5373079

src/cmd/gc/align.c

@@ -491,12 +491,12 @@ typeinit(void)
 	okforeq[TPTR64] = 1;
 	okforeq[TUNSAFEPTR] = 1;
 	okforeq[TINTER] = 1;
-	okforeq[TMAP] = 1;
 	okforeq[TCHAN] = 1;
-	okforeq[TFUNC] = 1;
 	okforeq[TSTRING] = 1;
 	okforeq[TBOOL] = 1;
-	okforeq[TARRAY] = 1;	// refined in typecheck
+	okforeq[TMAP] = 1;	// nil only; refined in typecheck
+	okforeq[TFUNC] = 1;	// nil only; refined in typecheck
+	okforeq[TARRAY] = 1;	// nil slice only; refined in typecheck
 
 	okforcmp[TSTRING] = 1;
 

src/cmd/gc/subr.c

@@ -547,6 +547,8 @@ maptype(Type *key, Type *val)
 		switch(key->etype) {
 		case TARRAY:
 		case TSTRUCT:
+		case TMAP:
+		case TFUNC:
 			yyerror("invalid map key type %T", key);
 			break;
 		case TFORW:

src/cmd/gc/swt.c

@@ -811,6 +811,7 @@ void
 typecheckswitch(Node *n)
 {
 	int top, lno, ptr;
+	char *nilonly;
 	Type *t, *missing, *have;
 	NodeList *l, *ll;
 	Node *ncase, *nvar;
@@ -818,6 +819,7 @@ typecheckswitch(Node *n)
 
 	lno = lineno;
 	typechecklist(n->ninit, Etop);
+	nilonly = nil;
 
 	if(n->ntest != N && n->ntest->op == OTYPESW) {
 		// type switch
@@ -835,6 +837,16 @@ typecheckswitch(Node *n)
 			t = n->ntest->type;
 		} else
 			t = types[TBOOL];
+		if(t) {
+			if(!okforeq[t->etype] || isfixedarray(t))
+				yyerror("cannot switch on %lN", n->ntest);
+			else if(t->etype == TARRAY)
+				nilonly = "slice";
+			else if(t->etype == TFUNC)
+				nilonly = "func";
+			else if(t->etype == TMAP)
+				nilonly = "map";
+		}
 	}
 	n->type = t;
 
@@ -865,6 +877,8 @@ typecheckswitch(Node *n)
 							yyerror("invalid case %N in switch on %N (mismatched types %T and %T)", ll->n, n->ntest, ll->n->type, t);
 						else
 							yyerror("invalid case %N in switch (mismatched types %T and bool)", ll->n, n->ntest, ll->n->type, t);
+					} else if(nilonly && !isconst(ll->n, CTNIL)) {
+						yyerror("invalid case %N in switch (can only compare %s %N to nil)", ll->n, nilonly, n->ntest);
 					}
 					break;
 				case Etype:	// type switch

src/cmd/gc/typecheck.c

@@ -445,8 +445,8 @@ reswitch:
 			yyerror("invalid operation: %N (operator %O not defined on %s)", n, op, typekind(et));
 			goto error;
 		}
-		// okfor allows any array == array;
-		// restrict to slice == nil and nil == slice.
+		// okfor allows any array == array, map == map, func == func.
+		// restrict to slice/map/func == nil and nil == slice/map/func.
 		if(l->type->etype == TARRAY && !isslice(l->type))
 			goto notokfor;
 		if(r->type->etype == TARRAY && !isslice(r->type))
@@ -455,6 +455,15 @@ reswitch:
 			yyerror("invalid operation: %N (slice can only be compared to nil)", n);
 			goto error;
 		}
+		if(l->type->etype == TMAP && !isnil(l) && !isnil(r)) {
+			yyerror("invalid operation: %N (map can only be compared to nil)", n);
+			goto error;
+		}
+		if(l->type->etype == TFUNC && !isnil(l) && !isnil(r)) {
+			yyerror("invalid operation: %N (func can only be compared to nil)", n);
+			goto error;
+		}
+		
 		t = l->type;
 		if(iscmp[n->op]) {
 			evconst(n);

test/closure.go

@@ -76,7 +76,6 @@ func h() {
 
 func newfunc() func(int) int { return func(x int) int { return x } }
 
-
 func main() {
 	go f()
 	check([]int{1, 4, 5, 4})
@@ -90,10 +89,6 @@ func main() {
 	check([]int{100, 200, 101, 201, 500, 101, 201, 500})
 
 	x, y := newfunc(), newfunc()
-	if x == y {
-		println("newfunc returned same func")
-		panic("fail")
-	}
 	if x(1) != 1 || y(2) != 2 {
 		println("newfunc returned broken funcs")
 		panic("fail")

test/cmp6.go

@@ -11,7 +11,7 @@ func use(bool) {}
 type T1 *int
 type T2 *int
 
-type T3 struct {}
+type T3 struct{}
 
 var t3 T3
 
@@ -21,12 +21,12 @@ func main() {
 	// so chan int can be compared against
 	// directional channels but channel of different
 	// direction cannot be compared against each other.
-	var c1 chan <-int
+	var c1 chan<- int
 	var c2 <-chan int
 	var c3 chan int
 
-	use(c1 == c2)	// ERROR "invalid operation|incompatible"
-	use(c2 == c1)	// ERROR "invalid operation|incompatible"
+	use(c1 == c2) // ERROR "invalid operation|incompatible"
+	use(c2 == c1) // ERROR "invalid operation|incompatible"
 	use(c1 == c3)
 	use(c2 == c2)
 	use(c3 == c1)
@@ -37,13 +37,21 @@ func main() {
 	var p2 T2
 	var p3 *int
 
-	use(p1 == p2)	// ERROR "invalid operation|incompatible"
-	use(p2 == p1)	// ERROR "invalid operation|incompatible"
+	use(p1 == p2) // ERROR "invalid operation|incompatible"
+	use(p2 == p1) // ERROR "invalid operation|incompatible"
 	use(p1 == p3)
 	use(p2 == p2)
 	use(p3 == p1)
 	use(p3 == p2)
 
 	// Comparison of structs should have a good message
-	use(t3 == t3)	// ERROR "struct|expected"
+	use(t3 == t3) // ERROR "struct|expected"
+
+	// Slices, functions, and maps too.
+	var x []int
+	var f func()
+	var m map[int]int
+	use(x == x) // ERROR "slice can only be compared to nil"
+	use(f == f) // ERROR "func can only be compared to nil"
+	use(m == m) // ERROR "map can only be compared to nil"
 }

test/fixedbugs/bug285.go

@@ -45,20 +45,6 @@ func main() {
 	mp[p] = 42
 	mp[&T{7}] = 42
 
-	type F func(x int)
-	f := func(x int) {}
-	mf := make(map[F]int)
-	mf[nil] = 42
-	mf[f] = 42
-	mf[func(x int) {}] = 42
-
-	type M map[int]int
-	m := make(M)
-	mm := make(map[M]int)
-	mm[nil] = 42
-	mm[m] = 42
-	mm[make(M)] = 42
-
 	type C chan int
 	c := make(C)
 	mc := make(map[C]int)

test/map1.go

@@ -30,12 +30,12 @@ var (
 	_ map[bool]v
 	_ map[string]v
 	_ map[chan int]v
-	_ map[func()]v
 	_ map[*int]v
-	_ map[map[int]int]v
 
 	// invalid
-	_ map[struct{}]v // ERROR "invalid map key"
-	_ map[[]int]v  // ERROR "invalid map key"
-	_ map[[10]int]v // ERROR "invalid map key"
+	_ map[struct{}]v    // ERROR "invalid map key"
+	_ map[[]int]v       // ERROR "invalid map key"
+	_ map[[10]int]v     // ERROR "invalid map key"
+	_ map[func()]v      // ERROR "invalid map key"
+	_ map[map[int]int]v // ERROR "invalid map key"
 )

test/switch.go

@@ -19,48 +19,75 @@ func main() {
 	hello := "hello"
 
 	switch true {
-	case i5 < 5: assert(false, "<")
-	case i5 == 5: assert(true, "!")
-	case i5 > 5: assert(false, ">")
+	case i5 < 5:
+		assert(false, "<")
+	case i5 == 5:
+		assert(true, "!")
+	case i5 > 5:
+		assert(false, ">")
 	}
 
 	switch {
-	case i5 < 5: assert(false, "<")
-	case i5 == 5: assert(true, "!")
-	case i5 > 5: assert(false, ">")
+	case i5 < 5:
+		assert(false, "<")
+	case i5 == 5:
+		assert(true, "!")
+	case i5 > 5:
+		assert(false, ">")
 	}
 
 	switch x := 5; true {
-	case i5 < x: assert(false, "<")
-	case i5 == x: assert(true, "!")
-	case i5 > x: assert(false, ">")
+	case i5 < x:
+		assert(false, "<")
+	case i5 == x:
+		assert(true, "!")
+	case i5 > x:
+		assert(false, ">")
 	}
 
 	switch x := 5; true {
-	case i5 < x: assert(false, "<")
-	case i5 == x: assert(true, "!")
-	case i5 > x: assert(false, ">")
+	case i5 < x:
+		assert(false, "<")
+	case i5 == x:
+		assert(true, "!")
+	case i5 > x:
+		assert(false, ">")
 	}
 
 	switch i5 {
-	case 0: assert(false, "0")
-	case 1: assert(false, "1")
-	case 2: assert(false, "2")
-	case 3: assert(false, "3")
-	case 4: assert(false, "4")
-	case 5: assert(true, "5")
-	case 6: assert(false, "6")
-	case 7: assert(false, "7")
-	case 8: assert(false, "8")
-	case 9: assert(false, "9")
-	default: assert(false, "default")
+	case 0:
+		assert(false, "0")
+	case 1:
+		assert(false, "1")
+	case 2:
+		assert(false, "2")
+	case 3:
+		assert(false, "3")
+	case 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
+	case 6:
+		assert(false, "6")
+	case 7:
+		assert(false, "7")
+	case 8:
+		assert(false, "8")
+	case 9:
+		assert(false, "9")
+	default:
+		assert(false, "default")
 	}
 
 	switch i5 {
-	case 0,1,2,3,4: assert(false, "4")
-	case 5: assert(true, "5")
-	case 6,7,8,9: assert(false, "9")
-	default: assert(false, "default")
+	case 0, 1, 2, 3, 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
+	case 6, 7, 8, 9:
+		assert(false, "9")
+	default:
+		assert(false, "default")
 	}
 
 	switch i5 {
@@ -68,72 +95,188 @@ func main() {
 	case 1:
 	case 2:
 	case 3:
-	case 4: assert(false, "4")
-	case 5: assert(true, "5")
+	case 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
 	case 6:
 	case 7:
 	case 8:
 	case 9:
-	default: assert(i5 == 5, "good")
+	default:
+		assert(i5 == 5, "good")
 	}
 
 	switch i5 {
-	case 0: dummy := 0; _ = dummy; fallthrough
-	case 1: dummy := 0; _ = dummy; fallthrough
-	case 2: dummy := 0; _ = dummy; fallthrough
-	case 3: dummy := 0; _ = dummy; fallthrough
-	case 4: dummy := 0; _ = dummy; assert(false, "4")
-	case 5: dummy := 0; _ = dummy; fallthrough
-	case 6: dummy := 0; _ = dummy; fallthrough
-	case 7: dummy := 0; _ = dummy; fallthrough
-	case 8: dummy := 0; _ = dummy; fallthrough
-	case 9: dummy := 0; _ = dummy; fallthrough
-	default: dummy := 0; _ = dummy; assert(i5 == 5, "good")
+	case 0:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 1:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 2:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 3:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 4:
+		dummy := 0
+		_ = dummy
+		assert(false, "4")
+	case 5:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 6:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 7:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 8:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 9:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	default:
+		dummy := 0
+		_ = dummy
+		assert(i5 == 5, "good")
 	}
 
 	fired := false
 	switch i5 {
-	case 0: dummy := 0; _ = dummy; fallthrough;  // tests scoping of cases
-	case 1: dummy := 0; _ = dummy; fallthrough
-	case 2: dummy := 0; _ = dummy; fallthrough
-	case 3: dummy := 0; _ = dummy; fallthrough
-	case 4: dummy := 0; _ = dummy; assert(false, "4")
-	case 5: dummy := 0; _ = dummy; fallthrough
-	case 6: dummy := 0; _ = dummy; fallthrough
-	case 7: dummy := 0; _ = dummy; fallthrough
-	case 8: dummy := 0; _ = dummy; fallthrough
-	case 9: dummy := 0; _ = dummy; fallthrough
-	default: dummy := 0; _ = dummy; fired = !fired; assert(i5 == 5, "good")
+	case 0:
+		dummy := 0
+		_ = dummy
+		fallthrough // tests scoping of cases
+	case 1:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 2:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 3:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 4:
+		dummy := 0
+		_ = dummy
+		assert(false, "4")
+	case 5:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 6:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 7:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 8:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 9:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	default:
+		dummy := 0
+		_ = dummy
+		fired = !fired
+		assert(i5 == 5, "good")
 	}
 	assert(fired, "fired")
 
 	count := 0
 	switch i5 {
-	case 0: count = count + 1; fallthrough
-	case 1: count = count + 1; fallthrough
-	case 2: count = count + 1; fallthrough
-	case 3: count = count + 1; fallthrough
-	case 4: count = count + 1; assert(false, "4")
-	case 5: count = count + 1; fallthrough
-	case 6: count = count + 1; fallthrough
-	case 7: count = count + 1; fallthrough
-	case 8: count = count + 1; fallthrough
-	case 9: count = count + 1; fallthrough
-	default: assert(i5 == count, "good")
+	case 0:
+		count = count + 1
+		fallthrough
+	case 1:
+		count = count + 1
+		fallthrough
+	case 2:
+		count = count + 1
+		fallthrough
+	case 3:
+		count = count + 1
+		fallthrough
+	case 4:
+		count = count + 1
+		assert(false, "4")
+	case 5:
+		count = count + 1
+		fallthrough
+	case 6:
+		count = count + 1
+		fallthrough
+	case 7:
+		count = count + 1
+		fallthrough
+	case 8:
+		count = count + 1
+		fallthrough
+	case 9:
+		count = count + 1
+		fallthrough
+	default:
+		assert(i5 == count, "good")
 	}
 	assert(fired, "fired")
 
 	switch hello {
-	case "wowie": assert(false, "wowie")
-	case "hello": assert(true, "hello")
-	case "jumpn": assert(false, "jumpn")
-	default: assert(false, "default")
+	case "wowie":
+		assert(false, "wowie")
+	case "hello":
+		assert(true, "hello")
+	case "jumpn":
+		assert(false, "jumpn")
+	default:
+		assert(false, "default")
 	}
 
 	fired = false
 	switch i := i5 + 2; i {
-	case i7: fired = true
-	default: assert(false, "fail")
+	case i7:
+		fired = true
+	default:
+		assert(false, "fail")
 	}
 	assert(fired, "var")
+
+	// switch on nil-only comparison types
+	switch f := func() {}; f {
+	case nil:
+		assert(false, "f should not be nil")
+	default:
+	}
+
+	switch m := make(map[int]int); m {
+	case nil:
+		assert(false, "m should not be nil")
+	default:
+	}
+
+	switch a := make([]int, 1); a {
+	case nil:
+		assert(false, "m should not be nil")
+	default:
+	}
 }

test/switch3.go

@@ -6,9 +6,8 @@
 
 package main
 
-
 type I interface {
-       M()
+	M()
 }
 
 func bad() {
@@ -16,11 +15,32 @@ func bad() {
 	var s string
 
 	switch i {
-	case s:  // ERROR "mismatched types string and I"
+	case s: // ERROR "mismatched types string and I"
 	}
 
 	switch s {
-	case i:  // ERROR "mismatched types I and string"
+	case i: // ERROR "mismatched types I and string"
+	}
+
+	var m, m1 map[int]int
+	switch m {
+	case nil:
+	case m1: // ERROR "can only compare map m to nil"
+	default:
+	}
+
+	var a, a1 []int
+	switch a {
+	case nil:
+	case a1: // ERROR "can only compare slice a to nil"
+	default:
+	}
+
+	var f, f1 func()
+	switch f {
+	case nil:
+	case f1: // ERROR "can only compare func f to nil"
+	default:
 	}
 }
 

test/typeswitch.go

@@ -82,9 +82,9 @@ func main() {
 		case []int:
 			assert(x[3] == 3 && i == Array, "array")
 		case map[string]int:
-			assert(x == m && i == Map, "map")
+			assert(x != nil && i == Map, "map")
 		case func(i int) interface{}:
-			assert(x == f && i == Func, "fun")
+			assert(x != nil && i == Func, "fun")
 		default:
 			assert(false, "unknown")
 		}
@@ -111,5 +111,4 @@ func main() {
 	default:
 		assert(false, "switch 4 unknown")
 	}
-
 }