Add workaround for MaybeUninit::uninit and bless tests

Author: fee1-dead

crates/rustc_codegen_spirv/src/builder/builder_methods.rs

@@ -3383,6 +3383,12 @@ impl<'a, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'tcx> {
             }
         }
 
+        // HACK(fee1-dead): `MaybeUninit` uses a union which we don't have very good support yet. Replacing all calls to it
+        // with an `Undef` serves the same purpose and fixes compiler errors 
+        if instance_def_id.is_some_and(|did| self.tcx.is_diagnostic_item(rustc_span::sym::maybe_uninit_uninit, did)) {
+            return self.undef(result_type);
+        }
+
         // Default: emit a regular function call
         let args = args.iter().map(|arg| arg.def(self)).collect::<Vec<_>>();
         self.emit()

tests/compiletests/ui/arch/subgroup/subgroup_composite_enum_err.stderr

@@ -43,7 +43,7 @@ LL + #[repr(crate::NoFrom)]
 LL - #[repr(C)]
 LL + #[repr(crate::NoRepr)]
     |
-     and 2 other candidates
+    = and 2 other candidates
 help: a type parameter with a similar name exists
     |
 LL - #[repr(C)]

tests/compiletests/ui/lang/core/unwrap_or.stderr

@@ -1,23 +1,20 @@
 %1 = OpFunction  %2  None %3
 %4 = OpLabel
-OpLine %5 13 11
-%6 = OpCompositeInsert  %7  %8 %9 0
-%10 = OpCompositeExtract  %11  %6 1
-OpLine %12 1026 14
-%13 = OpBitcast  %14  %8
-OpLine %12 1026 8
-%15 = OpINotEqual  %16  %13 %17
+OpLine %5 1035 14
+%6 = OpBitcast  %7  %8
+OpLine %5 1035 8
+%9 = OpINotEqual  %10  %6 %11
 OpNoLine
-OpSelectionMerge %18 None
-OpBranchConditional %15 %19 %20
-%19 = OpLabel
-OpBranch %18
-%20 = OpLabel
-OpBranch %18
-%18 = OpLabel
-%21 = OpPhi  %11  %10 %19 %22 %20
-OpLine %5 13 4
-OpStore %23 %21
+OpSelectionMerge %12 None
+OpBranchConditional %9 %13 %14
+%13 = OpLabel
+OpBranch %12
+%14 = OpLabel
+OpBranch %12
+%12 = OpLabel
+%15 = OpPhi  %16  %17 %13 %18 %14
+OpLine %19 13 4
+OpStore %20 %15
 OpNoLine
 OpReturn
 OpFunctionEnd