From 1401890ed5194aff3469be0b6919fd8fe2614c7b Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Sun, 28 Aug 2022 13:11:33 +0300
Subject: [PATCH] Sema: add error for switch on slice

Closes #12651
---
 src/Sema.zig                                  |  3 +++
 test/cases/compile_errors/switch_on_slice.zig | 13 +++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 test/cases/compile_errors/switch_on_slice.zig

diff --git a/src/Sema.zig b/src/Sema.zig
index 047d3f84c2..17d3b02da3 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -9003,6 +9003,9 @@ fn zirSwitchCond(
         .ErrorSet,
         .Enum,
         => {
+            if (operand_ty.isSlice()) {
+                return sema.fail(block, src, "switch on type '{}'", .{operand_ty.fmt(sema.mod)});
+            }
             if ((try sema.typeHasOnePossibleValue(block, operand_src, operand_ty))) |opv| {
                 return sema.addConstant(operand_ty, opv);
             }
diff --git a/test/cases/compile_errors/switch_on_slice.zig b/test/cases/compile_errors/switch_on_slice.zig
new file mode 100644
index 0000000000..b4644b132c
--- /dev/null
+++ b/test/cases/compile_errors/switch_on_slice.zig
@@ -0,0 +1,13 @@
+pub export fn entry() void {
+    var a: [:0]const u8 = "foo";
+    switch (a) {
+        "--version", "version" => unreachable,
+        else => {},
+    }
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:13: error: switch on type '[:0]const u8'