Sema: implement else capture value

The ZIR instructions `switch_capture_else` and `switch_capture_ref` are
removed because they are not needed. Instead, the prong index is set to
max int for the special prong.

Else prong with error sets is not handled yet.

Adds a new behavior test because there was not a prior on to cover only
the capture value of else on a switch.

1 files changed, 17 insertions, 0 deletions

diff --git a/test/behavior/while.zig b/test/behavior/while.zig
index d86e061d17..15dd9ee54c 100644
--- a/test/behavior/while.zig
+++ b/test/behavior/while.zig
@@ -266,3 +266,20 @@ test "while optional 2 break statements and an else" {
     try S.entry(true, false);
     comptime try S.entry(true, false);
 }
+
+test "while error 2 break statements and an else" {
+    if (@import("builtin").zig_backend != .stage1) return error.SkipZigTest; // TODO
+
+    const S = struct {
+        fn entry(opt_t: anyerror!bool, f: bool) !void {
+            var ok = false;
+            ok = while (opt_t) |t| {
+                if (f) break false;
+                if (t) break true;
+            } else |_| false;
+            try expect(ok);
+        }
+    };
+    try S.entry(true, false);
+    comptime try S.entry(true, false);
+}