Sema: preserve volatileness when constructing field pointers

Closes #12928

2 files changed, 27 insertions, 0 deletions

diff --git a/test/behavior.zig b/test/behavior.zig
index 2f1c609a55..552e68f1f7 100644
--- a/test/behavior.zig
+++ b/test/behavior.zig
@@ -93,6 +93,7 @@ test {
     _ = @import("behavior/bugs/12794.zig");
     _ = @import("behavior/bugs/12801-1.zig");
     _ = @import("behavior/bugs/12801-2.zig");
+    _ = @import("behavior/bugs/12928.zig");
     _ = @import("behavior/byteswap.zig");
     _ = @import("behavior/byval_arg_var.zig");
     _ = @import("behavior/call.zig");
diff --git a/test/behavior/bugs/12928.zig b/test/behavior/bugs/12928.zig
new file mode 100644
index 0000000000..56eca8cf60
--- /dev/null
+++ b/test/behavior/bugs/12928.zig
@@ -0,0 +1,26 @@
+const std = @import("std");
+const expect = std.testing.expect;
+const A = extern struct {
+    value: *volatile B,
+};
+const B = extern struct {
+    a: u32,
+    b: i32,
+};
+test {
+    var a: *A = undefined;
+    try expect(@TypeOf(&a.value.a) == *volatile u32);
+    try expect(@TypeOf(&a.value.b) == *volatile i32);
+}
+const C = extern struct {
+    value: *volatile D,
+};
+const D = extern union {
+    a: u32,
+    b: i32,
+};
+test {
+    var c: *C = undefined;
+    try expect(@TypeOf(&c.value.a) == *volatile u32);
+    try expect(@TypeOf(&c.value.b) == *volatile i32);
+}