diff --git a/test/cases/compile_errors/comptime_unreachable.zig b/test/cases/compile_errors/comptime_unreachable.zig
new file mode 100644
index 0000000000000000000000000000000000000000..74b35165854f2bfa0bb9552b67da998ef0251b39
--- /dev/null
+++ b/test/cases/compile_errors/comptime_unreachable.zig
@@ -0,0 +1,9 @@
+pub export fn entry() void {
+    comptime unreachable;
+}
+
+// error
+// target=native
+// backend=stage2
+//
+// :2:14: error: reached unreachable code
diff --git a/test/cases/compile_errors/constant_inside_comptime_function_has_compile_error.zig b/test/cases/compile_errors/constant_inside_comptime_function_has_compile_error.zig
new file mode 100644
index 0000000000000000000000000000000000000000..2b67390b05b2ec7e22608045d5e658810a4b596d
--- /dev/null
+++ b/test/cases/compile_errors/constant_inside_comptime_function_has_compile_error.zig
@@ -0,0 +1,21 @@
+const ContextAllocator = MemoryPool(usize);
+
+pub fn MemoryPool(comptime T: type) type {
+    const free_list_t = @compileError("aoeu",);
+    _ = T;
+
+    return struct {
+        free_list: free_list_t,
+    };
+}
+
+export fn entry() void {
+    var allocator: ContextAllocator = undefined;
+    _ = allocator;
+}
+
+// error
+// target=native
+//
+// :4:5: error: unreachable code
+// :4:25: note: control flow is diverted here
diff --git a/test/cases/compile_errors/duplicate-unused_labels.zig b/test/cases/compile_errors/duplicate-unused_labels.zig
new file mode 100644
index 0000000000000000000000000000000000000000..4bfc6c596012082af8e971d5ab932f86a01c8c5c
--- /dev/null
+++ b/test/cases/compile_errors/duplicate-unused_labels.zig
@@ -0,0 +1,31 @@
+comptime {
+    blk: { blk: while (false) {} }
+}
+comptime {
+    blk: while (false) { blk: for (@as([0]void, undefined)) |_| {} }
+}
+comptime {
+    blk: for (@as([0]void, undefined)) |_| { blk: {} }
+}
+comptime {
+    blk: {}
+}
+comptime {
+    blk: while(false) {}
+}
+comptime {
+    blk: for(@as([0]void, undefined)) |_| {}
+}
+
+// error
+// target=native
+//
+// :2:12: error: redefinition of label 'blk'
+// :2:5: note: previous definition here
+// :5:26: error: redefinition of label 'blk'
+// :5:5: note: previous definition here
+// :8:46: error: redefinition of label 'blk'
+// :8:5: note: previous definition here
+// :11:5: error: unused block label
+// :14:5: error: unused while loop label
+// :17:5: error: unused for loop label
diff --git a/test/cases/compile_errors/embed_outside_package.zig b/test/cases/compile_errors/embed_outside_package.zig
new file mode 100644
index 0000000000000000000000000000000000000000..2003adb06199e8df8136ea6941d4ac346219f6bb
--- /dev/null
+++ b/test/cases/compile_errors/embed_outside_package.zig
@@ -0,0 +1,8 @@
+export fn a() usize {
+    return @embedFile("/root/foo").len;
+}
+
+// error
+// target=native
+//
+//:2:23: error: embed of file outside package path: '/root/foo'
diff --git a/test/cases/compile_errors/import_outside_package.zig b/test/cases/compile_errors/import_outside_package.zig
new file mode 100644
index 0000000000000000000000000000000000000000..59a75e2745a22d2f1b84d40d0555c4e7dc1ae881
--- /dev/null
+++ b/test/cases/compile_errors/import_outside_package.zig
@@ -0,0 +1,8 @@
+export fn a() usize {
+    return @import("../../above.zig").len;
+}
+
+// error
+// target=native
+//
+// :2:20: error: import of file outside package path: '../../above.zig'
diff --git a/test/cases/compile_errors/out_of_bounds_index.zig b/test/cases/compile_errors/out_of_bounds_index.zig
new file mode 100644
index 0000000000000000000000000000000000000000..3f5b71d530fdbe6f29ba8f2435a13a57f3e7b504
--- /dev/null
+++ b/test/cases/compile_errors/out_of_bounds_index.zig
@@ -0,0 +1,29 @@
+comptime {
+    var array = [_:0]u8{ 1, 2, 3, 4 };
+    var src_slice: [:0]u8 = &array;
+    var slice = src_slice[2..6];
+    _ = slice;
+}
+comptime {
+    var array = [_:0]u8{ 1, 2, 3, 4 };
+    var slice = array[2..6];
+    _ = slice;
+}
+comptime {
+    var array = [_]u8{ 1, 2, 3, 4 };
+    var slice = array[2..5];
+    _ = slice;
+}
+comptime {
+    var array = [_:0]u8{ 1, 2, 3, 4 };
+    var slice = array[3..2];
+    _ = slice;
+}
+
+// error
+// target=native
+//
+// :4:30: error: end index 6 out of bounds for slice of length 4 +1 (sentinel)
+// :9:26: error: end index 6 out of bounds for array of length 4 +1 (sentinel)
+// :14:26: error: end index 5 out of bounds for array of length 4
+// :19:23: error: start index 3 is larger than end index 2
diff --git a/test/cases/compile_errors/reified_enum_field_value_overflow.zig b/test/cases/compile_errors/reified_enum_field_value_overflow.zig
new file mode 100644
index 0000000000000000000000000000000000000000..ad8596ebccd724074f8222b4543984d4faf98929
--- /dev/null
+++ b/test/cases/compile_errors/reified_enum_field_value_overflow.zig
@@ -0,0 +1,20 @@
+comptime {
+    const E = @Type(.{ .Enum = .{
+        .layout = .Auto,
+        .tag_type = u1,
+        .fields = &.{
+            .{ .name = "f0", .value = 0 },
+            .{ .name = "f1", .value = 1 },
+            .{ .name = "f2", .value = 2 },
+        },
+        .decls = &.{},
+        .is_exhaustive = true,
+    } });
+    _ = E;
+}
+
+// error
+// target=native
+// backend=stage2
+//
+// :2:15: error: field 'f2' with enumeration value '2' is too large for backing int type 'u1'
diff --git a/test/cases/compile_errors/slice_of_null_pointer.zig b/test/cases/compile_errors/slice_of_null_pointer.zig
new file mode 100644
index 0000000000000000000000000000000000000000..7f2c74a8a62bfc65116889043afdcd75e1d04ddd
--- /dev/null
+++ b/test/cases/compile_errors/slice_of_null_pointer.zig
@@ -0,0 +1,11 @@
+comptime {
+    var x: [*c]u8 = null;
+    var runtime_len: usize = 0;
+    var y = x[0..runtime_len];
+    _ = y;
+}
+
+// error
+// target=native
+//
+// :4:14: error: slice of null pointer
diff --git a/test/cases/compile_errors/stage2/comptime_unreachable.zig b/test/cases/compile_errors/stage2/comptime_unreachable.zig
deleted file mode 100644
index 74b35165854f2bfa0bb9552b67da998ef0251b39..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/comptime_unreachable.zig
+++ /dev/null
@@ -1,9 +0,0 @@
-pub export fn entry() void {
-    comptime unreachable;
-}
-
-// error
-// target=native
-// backend=stage2
-//
-// :2:14: error: reached unreachable code
diff --git a/test/cases/compile_errors/stage2/constant_inside_comptime_function_has_compile_error.zig b/test/cases/compile_errors/stage2/constant_inside_comptime_function_has_compile_error.zig
deleted file mode 100644
index 2b67390b05b2ec7e22608045d5e658810a4b596d..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/constant_inside_comptime_function_has_compile_error.zig
+++ /dev/null
@@ -1,21 +0,0 @@
-const ContextAllocator = MemoryPool(usize);
-
-pub fn MemoryPool(comptime T: type) type {
-    const free_list_t = @compileError("aoeu",);
-    _ = T;
-
-    return struct {
-        free_list: free_list_t,
-    };
-}
-
-export fn entry() void {
-    var allocator: ContextAllocator = undefined;
-    _ = allocator;
-}
-
-// error
-// target=native
-//
-// :4:5: error: unreachable code
-// :4:25: note: control flow is diverted here
diff --git a/test/cases/compile_errors/stage2/duplicate-unused_labels.zig b/test/cases/compile_errors/stage2/duplicate-unused_labels.zig
deleted file mode 100644
index 4bfc6c596012082af8e971d5ab932f86a01c8c5c..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/duplicate-unused_labels.zig
+++ /dev/null
@@ -1,31 +0,0 @@
-comptime {
-    blk: { blk: while (false) {} }
-}
-comptime {
-    blk: while (false) { blk: for (@as([0]void, undefined)) |_| {} }
-}
-comptime {
-    blk: for (@as([0]void, undefined)) |_| { blk: {} }
-}
-comptime {
-    blk: {}
-}
-comptime {
-    blk: while(false) {}
-}
-comptime {
-    blk: for(@as([0]void, undefined)) |_| {}
-}
-
-// error
-// target=native
-//
-// :2:12: error: redefinition of label 'blk'
-// :2:5: note: previous definition here
-// :5:26: error: redefinition of label 'blk'
-// :5:5: note: previous definition here
-// :8:46: error: redefinition of label 'blk'
-// :8:5: note: previous definition here
-// :11:5: error: unused block label
-// :14:5: error: unused while loop label
-// :17:5: error: unused for loop label
diff --git a/test/cases/compile_errors/stage2/embed_outside_package.zig b/test/cases/compile_errors/stage2/embed_outside_package.zig
deleted file mode 100644
index 2003adb06199e8df8136ea6941d4ac346219f6bb..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/embed_outside_package.zig
+++ /dev/null
@@ -1,8 +0,0 @@
-export fn a() usize {
-    return @embedFile("/root/foo").len;
-}
-
-// error
-// target=native
-//
-//:2:23: error: embed of file outside package path: '/root/foo'
diff --git a/test/cases/compile_errors/stage2/import_outside_package.zig b/test/cases/compile_errors/stage2/import_outside_package.zig
deleted file mode 100644
index 59a75e2745a22d2f1b84d40d0555c4e7dc1ae881..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/import_outside_package.zig
+++ /dev/null
@@ -1,8 +0,0 @@
-export fn a() usize {
-    return @import("../../above.zig").len;
-}
-
-// error
-// target=native
-//
-// :2:20: error: import of file outside package path: '../../above.zig'
diff --git a/test/cases/compile_errors/stage2/out_of_bounds_index.zig b/test/cases/compile_errors/stage2/out_of_bounds_index.zig
deleted file mode 100644
index 3f5b71d530fdbe6f29ba8f2435a13a57f3e7b504..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/out_of_bounds_index.zig
+++ /dev/null
@@ -1,29 +0,0 @@
-comptime {
-    var array = [_:0]u8{ 1, 2, 3, 4 };
-    var src_slice: [:0]u8 = &array;
-    var slice = src_slice[2..6];
-    _ = slice;
-}
-comptime {
-    var array = [_:0]u8{ 1, 2, 3, 4 };
-    var slice = array[2..6];
-    _ = slice;
-}
-comptime {
-    var array = [_]u8{ 1, 2, 3, 4 };
-    var slice = array[2..5];
-    _ = slice;
-}
-comptime {
-    var array = [_:0]u8{ 1, 2, 3, 4 };
-    var slice = array[3..2];
-    _ = slice;
-}
-
-// error
-// target=native
-//
-// :4:30: error: end index 6 out of bounds for slice of length 4 +1 (sentinel)
-// :9:26: error: end index 6 out of bounds for array of length 4 +1 (sentinel)
-// :14:26: error: end index 5 out of bounds for array of length 4
-// :19:23: error: start index 3 is larger than end index 2
diff --git a/test/cases/compile_errors/stage2/reified_enum_field_value_overflow.zig b/test/cases/compile_errors/stage2/reified_enum_field_value_overflow.zig
deleted file mode 100644
index ad8596ebccd724074f8222b4543984d4faf98929..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/reified_enum_field_value_overflow.zig
+++ /dev/null
@@ -1,20 +0,0 @@
-comptime {
-    const E = @Type(.{ .Enum = .{
-        .layout = .Auto,
-        .tag_type = u1,
-        .fields = &.{
-            .{ .name = "f0", .value = 0 },
-            .{ .name = "f1", .value = 1 },
-            .{ .name = "f2", .value = 2 },
-        },
-        .decls = &.{},
-        .is_exhaustive = true,
-    } });
-    _ = E;
-}
-
-// error
-// target=native
-// backend=stage2
-//
-// :2:15: error: field 'f2' with enumeration value '2' is too large for backing int type 'u1'
diff --git a/test/cases/compile_errors/stage2/slice_of_null_pointer.zig b/test/cases/compile_errors/stage2/slice_of_null_pointer.zig
deleted file mode 100644
index 7f2c74a8a62bfc65116889043afdcd75e1d04ddd..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/slice_of_null_pointer.zig
+++ /dev/null
@@ -1,11 +0,0 @@
-comptime {
-    var x: [*c]u8 = null;
-    var runtime_len: usize = 0;
-    var y = x[0..runtime_len];
-    _ = y;
-}
-
-// error
-// target=native
-//
-// :4:14: error: slice of null pointer
diff --git a/test/cases/compile_errors/stage2/struct_duplicate_field_name.zig b/test/cases/compile_errors/stage2/struct_duplicate_field_name.zig
deleted file mode 100644
index 7e4434f1d92fa353d9fccff5f2c403fae90c9978..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/struct_duplicate_field_name.zig
+++ /dev/null
@@ -1,16 +0,0 @@
-const S = struct {
-    foo: u32,
-    foo: u32,
-};
-
-export fn entry() void {
-    const s: S = .{ .foo = 100 };
-    _ = s;
-}
-
-// error
-// target=native
-//
-// :3:5: error: duplicate struct field: 'foo'
-// :2:5: note: other field here
-// :1:11: note: struct declared here
diff --git a/test/cases/compile_errors/stage2/tuple_ptr_to_mut_slice.zig b/test/cases/compile_errors/stage2/tuple_ptr_to_mut_slice.zig
deleted file mode 100644
index 24e4753563aa0d067c94c47fb5ea5260f5ff747c..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/tuple_ptr_to_mut_slice.zig
+++ /dev/null
@@ -1,32 +0,0 @@
-export fn entry1() void {
-    var a = .{ 1, 2, 3 };
-    _ = @as([]u8, &a);
-}
-export fn entry2() void {
-    var a = .{ @as(u8, 1), @as(u8, 2), @as(u8, 3) };
-    _ = @as([]u8, &a);
-}
-
-// runtime values
-var vals = [_]u7{ 4, 5, 6 };
-export fn entry3() void {
-    var a = .{ vals[0], vals[1], vals[2] };
-    _ = @as([]u8, &a);
-}
-export fn entry4() void {
-    var a = .{ @as(u8, vals[0]), @as(u8, vals[1]), @as(u8, vals[2]) };
-    _ = @as([]u8, &a);
-}
-
-// error
-// backend=stage2
-// target=native
-//
-// :3:19: error: cannot cast pointer to tuple to '[]u8'
-// :3:19: note: pointers to tuples can only coerce to constant pointers
-// :7:19: error: cannot cast pointer to tuple to '[]u8'
-// :7:19: note: pointers to tuples can only coerce to constant pointers
-// :14:19: error: cannot cast pointer to tuple to '[]u8'
-// :14:19: note: pointers to tuples can only coerce to constant pointers
-// :18:19: error: cannot cast pointer to tuple to '[]u8'
-// :18:19: note: pointers to tuples can only coerce to constant pointers
diff --git a/test/cases/compile_errors/stage2/union_access_of_inactive_field.zig b/test/cases/compile_errors/stage2/union_access_of_inactive_field.zig
deleted file mode 100644
index 4f72914216fce157fc689d84d177add5ade64fcc..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_access_of_inactive_field.zig
+++ /dev/null
@@ -1,15 +0,0 @@
-const U = union {
-    a: void,
-    b: u64,
-};
-comptime {
-    var u: U = .{ .a = {} };
-    const v = u.b;
-    _ = v;
-}
-
-// error
-// target=native
-//
-// :7:16: error: access of union field 'b' while field 'a' is active
-// :1:11: note: union declared here
diff --git a/test/cases/compile_errors/stage2/union_duplicate_enum_field.zig b/test/cases/compile_errors/stage2/union_duplicate_enum_field.zig
deleted file mode 100644
index 44eb58e01449d22d53bf6382c8e61d0cc69b9cb9..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_duplicate_enum_field.zig
+++ /dev/null
@@ -1,17 +0,0 @@
-const E = enum { a, b };
-const U = union(E) {
-    a: u32,
-    a: u32,
-};
-
-export fn foo() void {
-    var u: U = .{ .a = 123 };
-    _ = u;
-}
-
-// error
-// target=native
-//
-// :4:5: error: duplicate union field: 'a'
-// :3:5: note: other field here
-// :2:11: note: union declared here
diff --git a/test/cases/compile_errors/stage2/union_duplicate_field_definition.zig b/test/cases/compile_errors/stage2/union_duplicate_field_definition.zig
deleted file mode 100644
index 7993f27141f54f163bc29e32dfe0ed46054c67c4..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_duplicate_field_definition.zig
+++ /dev/null
@@ -1,16 +0,0 @@
-const U = union {
-    foo: u32,
-    foo: u32,
-};
-
-export fn entry() void {
-    const u: U = .{ .foo = 100 };
-    _ = u;
-}
-
-// error
-// target=native
-//
-// :3:5: error: duplicate union field: 'foo'
-// :2:5: note: other field here
-// :1:11: note: union declared here
diff --git a/test/cases/compile_errors/stage2/union_enum_field_missing.zig b/test/cases/compile_errors/stage2/union_enum_field_missing.zig
deleted file mode 100644
index 81bc83cf181d959f9519e9900650eb0110c49812..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_enum_field_missing.zig
+++ /dev/null
@@ -1,21 +0,0 @@
-const E = enum {
-    a,
-    b,
-    c,
-};
-
-const U = union(E) {
-    a: i32,
-    b: f64,
-};
-
-export fn entry() usize {
-    return @sizeOf(U);
-}
-
-// error
-// target=native
-//
-// :7:11: error: enum field(s) missing in union
-// :4:5: note: field 'c' missing, declared here
-// :1:11: note: enum declared here
diff --git a/test/cases/compile_errors/stage2/union_extra_field.zig b/test/cases/compile_errors/stage2/union_extra_field.zig
deleted file mode 100644
index 6d1c644bc6888e64140a2ce870d2b68c8b076982..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_extra_field.zig
+++ /dev/null
@@ -1,20 +0,0 @@
-const E = enum {
-    a,
-    b,
-    c,
-};
-const U = union(E) {
-    a: i32,
-    b: f64,
-    c: f64,
-    d: f64,
-};
-export fn entry() usize {
-    return @sizeOf(U);
-}
-
-// error
-// target=native
-//
-// :10:5: error: no field named 'd' in enum 'tmp.E'
-// :1:11: note: enum declared here
diff --git a/test/cases/compile_errors/stage2/union_runtime_coercion_from_enum.zig b/test/cases/compile_errors/stage2/union_runtime_coercion_from_enum.zig
deleted file mode 100644
index 9020e9d5d7d202ef14c9c2660bee33df59508901..0000000000000000000000000000000000000000
--- a/test/cases/compile_errors/stage2/union_runtime_coercion_from_enum.zig
+++ /dev/null
@@ -1,23 +0,0 @@
-const E = enum {
-    a,
-    b,
-};
-const U = union(E) {
-    a: u32,
-    b: u64,
-};
-fn foo() E {
-    return E.b;
-}
-export fn doTheTest() u64 {
-    var u: U = foo();
-    return u.b;
-}
-
-// error
-// target=native
-//
-// :13:19: error: runtime coercion from enum 'tmp.E' to union 'tmp.U' which has non-void fields
-// :6:5: note: field 'a' has type 'u32'
-// :7:5: note: field 'b' has type 'u64'
-// :5:11: note: union declared here
diff --git a/test/cases/compile_errors/struct_duplicate_field_name.zig b/test/cases/compile_errors/struct_duplicate_field_name.zig
new file mode 100644
index 0000000000000000000000000000000000000000..7e4434f1d92fa353d9fccff5f2c403fae90c9978
--- /dev/null
+++ b/test/cases/compile_errors/struct_duplicate_field_name.zig
@@ -0,0 +1,16 @@
+const S = struct {
+    foo: u32,
+    foo: u32,
+};
+
+export fn entry() void {
+    const s: S = .{ .foo = 100 };
+    _ = s;
+}
+
+// error
+// target=native
+//
+// :3:5: error: duplicate struct field: 'foo'
+// :2:5: note: other field here
+// :1:11: note: struct declared here
diff --git a/test/cases/compile_errors/tuple_ptr_to_mut_slice.zig b/test/cases/compile_errors/tuple_ptr_to_mut_slice.zig
new file mode 100644
index 0000000000000000000000000000000000000000..24e4753563aa0d067c94c47fb5ea5260f5ff747c
--- /dev/null
+++ b/test/cases/compile_errors/tuple_ptr_to_mut_slice.zig
@@ -0,0 +1,32 @@
+export fn entry1() void {
+    var a = .{ 1, 2, 3 };
+    _ = @as([]u8, &a);
+}
+export fn entry2() void {
+    var a = .{ @as(u8, 1), @as(u8, 2), @as(u8, 3) };
+    _ = @as([]u8, &a);
+}
+
+// runtime values
+var vals = [_]u7{ 4, 5, 6 };
+export fn entry3() void {
+    var a = .{ vals[0], vals[1], vals[2] };
+    _ = @as([]u8, &a);
+}
+export fn entry4() void {
+    var a = .{ @as(u8, vals[0]), @as(u8, vals[1]), @as(u8, vals[2]) };
+    _ = @as([]u8, &a);
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:19: error: cannot cast pointer to tuple to '[]u8'
+// :3:19: note: pointers to tuples can only coerce to constant pointers
+// :7:19: error: cannot cast pointer to tuple to '[]u8'
+// :7:19: note: pointers to tuples can only coerce to constant pointers
+// :14:19: error: cannot cast pointer to tuple to '[]u8'
+// :14:19: note: pointers to tuples can only coerce to constant pointers
+// :18:19: error: cannot cast pointer to tuple to '[]u8'
+// :18:19: note: pointers to tuples can only coerce to constant pointers
diff --git a/test/cases/compile_errors/union_access_of_inactive_field.zig b/test/cases/compile_errors/union_access_of_inactive_field.zig
new file mode 100644
index 0000000000000000000000000000000000000000..4f72914216fce157fc689d84d177add5ade64fcc
--- /dev/null
+++ b/test/cases/compile_errors/union_access_of_inactive_field.zig
@@ -0,0 +1,15 @@
+const U = union {
+    a: void,
+    b: u64,
+};
+comptime {
+    var u: U = .{ .a = {} };
+    const v = u.b;
+    _ = v;
+}
+
+// error
+// target=native
+//
+// :7:16: error: access of union field 'b' while field 'a' is active
+// :1:11: note: union declared here
diff --git a/test/cases/compile_errors/union_duplicate_enum_field.zig b/test/cases/compile_errors/union_duplicate_enum_field.zig
new file mode 100644
index 0000000000000000000000000000000000000000..44eb58e01449d22d53bf6382c8e61d0cc69b9cb9
--- /dev/null
+++ b/test/cases/compile_errors/union_duplicate_enum_field.zig
@@ -0,0 +1,17 @@
+const E = enum { a, b };
+const U = union(E) {
+    a: u32,
+    a: u32,
+};
+
+export fn foo() void {
+    var u: U = .{ .a = 123 };
+    _ = u;
+}
+
+// error
+// target=native
+//
+// :4:5: error: duplicate union field: 'a'
+// :3:5: note: other field here
+// :2:11: note: union declared here
diff --git a/test/cases/compile_errors/union_duplicate_field_definition.zig b/test/cases/compile_errors/union_duplicate_field_definition.zig
new file mode 100644
index 0000000000000000000000000000000000000000..7993f27141f54f163bc29e32dfe0ed46054c67c4
--- /dev/null
+++ b/test/cases/compile_errors/union_duplicate_field_definition.zig
@@ -0,0 +1,16 @@
+const U = union {
+    foo: u32,
+    foo: u32,
+};
+
+export fn entry() void {
+    const u: U = .{ .foo = 100 };
+    _ = u;
+}
+
+// error
+// target=native
+//
+// :3:5: error: duplicate union field: 'foo'
+// :2:5: note: other field here
+// :1:11: note: union declared here
diff --git a/test/cases/compile_errors/union_enum_field_missing.zig b/test/cases/compile_errors/union_enum_field_missing.zig
new file mode 100644
index 0000000000000000000000000000000000000000..81bc83cf181d959f9519e9900650eb0110c49812
--- /dev/null
+++ b/test/cases/compile_errors/union_enum_field_missing.zig
@@ -0,0 +1,21 @@
+const E = enum {
+    a,
+    b,
+    c,
+};
+
+const U = union(E) {
+    a: i32,
+    b: f64,
+};
+
+export fn entry() usize {
+    return @sizeOf(U);
+}
+
+// error
+// target=native
+//
+// :7:11: error: enum field(s) missing in union
+// :4:5: note: field 'c' missing, declared here
+// :1:11: note: enum declared here
diff --git a/test/cases/compile_errors/union_extra_field.zig b/test/cases/compile_errors/union_extra_field.zig
new file mode 100644
index 0000000000000000000000000000000000000000..6d1c644bc6888e64140a2ce870d2b68c8b076982
--- /dev/null
+++ b/test/cases/compile_errors/union_extra_field.zig
@@ -0,0 +1,20 @@
+const E = enum {
+    a,
+    b,
+    c,
+};
+const U = union(E) {
+    a: i32,
+    b: f64,
+    c: f64,
+    d: f64,
+};
+export fn entry() usize {
+    return @sizeOf(U);
+}
+
+// error
+// target=native
+//
+// :10:5: error: no field named 'd' in enum 'tmp.E'
+// :1:11: note: enum declared here
diff --git a/test/cases/compile_errors/union_runtime_coercion_from_enum.zig b/test/cases/compile_errors/union_runtime_coercion_from_enum.zig
new file mode 100644
index 0000000000000000000000000000000000000000..9020e9d5d7d202ef14c9c2660bee33df59508901
--- /dev/null
+++ b/test/cases/compile_errors/union_runtime_coercion_from_enum.zig
@@ -0,0 +1,23 @@
+const E = enum {
+    a,
+    b,
+};
+const U = union(E) {
+    a: u32,
+    b: u64,
+};
+fn foo() E {
+    return E.b;
+}
+export fn doTheTest() u64 {
+    var u: U = foo();
+    return u.b;
+}
+
+// error
+// target=native
+//
+// :13:19: error: runtime coercion from enum 'tmp.E' to union 'tmp.U' which has non-void fields
+// :6:5: note: field 'a' has type 'u32'
+// :7:5: note: field 'b' has type 'u64'
+// :5:11: note: union declared here