[clang] [CIR] Upstream minimal support for structure types (PR #135105)

[Henrich Lauko via cfe-commits]

================
@@ -67,6 +72,166 @@ void CIRDialect::printType(Type type, DialectAsmPrinter &os) const {
   llvm::report_fatal_error("printer is missing a handler for this type");
 }
 
+//===----------------------------------------------------------------------===//
+// RecordType Definitions
+//===----------------------------------------------------------------------===//
+
+Type RecordType::parse(mlir::AsmParser &parser) {
+  FailureOr<AsmParser::CyclicParseReset> cyclicParseGuard;
+  const auto loc = parser.getCurrentLocation();
+  const auto eLoc = parser.getEncodedSourceLoc(loc);
+  RecordKind kind;
+  auto *context = parser.getContext();
+
+  if (parser.parseLess())
+    return {};
+
+  // TODO(cir): in the future we should probably separate types for different
+  // source language declarations such as cir.record and cir.union
+  if (parser.parseOptionalKeyword("struct").succeeded())
+    kind = RecordKind::Struct;
+  else if (parser.parseOptionalKeyword("union").succeeded())
+    kind = RecordKind::Union;
+  else {
+    parser.emitError(loc, "unknown record type");
+    return {};
+  }
+
+  mlir::StringAttr name;
+  parser.parseOptionalAttribute(name);
+
+  // Is a self reference: ensure referenced type was parsed.
+  if (name && parser.parseOptionalGreater().succeeded()) {
+    auto type = getChecked(eLoc, context, name, kind);
----------------
xlauko wrote:

```suggestion
    Type type = getChecked(eLoc, context, name, kind);
```

https://github.com/llvm/llvm-project/pull/135105