objc: Fix handling of break stmt inside of switch inside of ObjC foreach [PR103639]

The r11-3302-g3696a50beeb73f changes broke the following ObjC testcase.
in_statement is either 0 (not in a looping statement), various IN_* flags
for various kinds of looping statements (or OpenMP structured blocks) or
those flags ored with IN_SWITCH_STMT when a switch appears inside of those
contexts.  This is because break binds to switch in that last case, but
continue binds to the looping construct in that case.
The c_finish_bc_stmt function performs diagnostics on incorrect
break/continue uses and then checks if in_statement & IN_OBJC_FOREACH
and in that case jumps to the label provided by the caller, otherwise
emits a BREAK_STMT or CONTINUE_STMT.  This is incorrect if we have
ObjC foreach with switch nested in it and break inside of that,
in_statement in that case is IN_OBJC_FOREACH | IN_SWITCH_STMT and
is_break is true.  We want to handle it like other breaks inside of
switch, i.e. emit a BREAK_STMT.

The following patch fixes that.

2022-01-01  Jakub Jelinek  <jakub@redhat.com>

	PR objc/103639
	* c-typeck.c (c_finish_bc_stmt): For break inside of switch inside of
	ObjC foreach, emit normal BREAK_STMT rather than goto to label.

2022-01-01  Iain Sandoe  <iain@sandoe.co.uk>

	PR objc/103639
	* objc.dg/pr103639.m: New test.

gcc/c/c-typeck.c

@@ -11257,7 +11257,8 @@ c_finish_bc_stmt (location_t loc, tree label, bool is_break)
 
   if (skip)
     return NULL_TREE;
-  else if (in_statement & IN_OBJC_FOREACH)
+  else if ((in_statement & IN_OBJC_FOREACH)
+	   && !(is_break && (in_statement & IN_SWITCH_STMT)))
     {
       /* The foreach expander produces low-level code using gotos instead
 	 of a structured loop construct.  */

gcc/testsuite/objc.dg/pr103639.m

@@ -0,0 +1,101 @@
+/* PR objc/103639 */
+/* { dg-do run } */
+/* { dg-skip-if "No NeXT fast enum. pre-Darwin9" { *-*-darwin[5-8]* } { "-fnext-runtime" } { "" } } */
+/* { dg-xfail-run-if "Needs OBJC2 ABI" { *-*-darwin* && { lp64 && { ! objc2 } } } { "-fnext-runtime" } { "" } } */
+/* { dg-additional-sources "../objc-obj-c++-shared/nsconstantstring-class-impl.m" } */
+/* { dg-additional-options "-mno-constant-cfstrings" { target *-*-darwin* } } */
+/* { dg-additional-options "-Wno-objc-root-class" } */
+
+#import "../objc-obj-c++-shared/TestsuiteObject.m"
+#ifndef __NEXT_RUNTIME__
+#include <objc/NXConstStr.h>
+#else
+#include "../objc-obj-c++-shared/nsconstantstring-class.h"
+#endif
+
+extern int printf (const char *, ...);
+#include <stdlib.h>
+
+/* A mini-array implementation that can be used to test fast
+    enumeration.  You create the array with some objects; you can
+    mutate the array, and you can fast-enumerate it.
+ */
+@interface MyArray : TestsuiteObject
+{
+  unsigned int length;
+  id *objects;
+  unsigned long mutated;
+}
+- (id) initWithLength: (unsigned int)l  objects: (id *)o;
+- (void) mutate;
+- (unsigned long)countByEnumeratingWithState: (struct __objcFastEnumerationState *)state
+                                     objects:(id *)stackbuf 
+                                       count:(unsigned long)len;
+@end
+
+@implementation MyArray : TestsuiteObject
+- (id) initWithLength: (unsigned int)l
+	      objects: (id *)o
+{
+  length = l;
+  objects = o;
+  mutated = 0;
+  return self;
+}
+- (void) mutate
+{
+  mutated = 1;
+}
+- (unsigned long)countByEnumeratingWithState: (struct __objcFastEnumerationState*)state 
+		  		     objects: (id*)stackbuf
+			 	       count: (unsigned long)len
+{
+  unsigned long i, batch_size;
+
+  /* We keep how many objects we served in the state->state counter.  So the next batch
+     will contain up to length - state->state objects.  */
+  batch_size = length - state->state;
+
+  /* Make obvious adjustments.  */
+  if (batch_size < 0)
+    batch_size = 0;
+
+  if (batch_size > len)
+    batch_size = len;
+
+  /* Copy the objects.  */
+  for (i = 0; i < batch_size; i++)
+    stackbuf[i] = objects[i];
+
+  state->state += batch_size;
+  state->itemsPtr = stackbuf;
+  state->mutationsPtr = &mutated;
+
+  return batch_size;
+}
+@end
+
+int check = 0;
+
+int
+main()
+{
+  id *objects = malloc (sizeof (id) * 2);
+  objects[0] = @"a";
+  objects[1] = @"b";
+
+  MyArray *array = [[MyArray alloc] initWithLength: 2 objects: objects];
+
+  int someVar = 0;
+  for (id object in array) {
+    switch (someVar) {
+      case 0:
+	break;
+    }
+    ++check;
+  }
+
+  if (check != 2)
+    abort ();
+  return 0;
+}