Fix crash in MLIR opaque attribute parser

[mehdi_amini]

Summary

An assertion is triggered with the dialect is malformed.

[rriddle]

mlir/lib/Parser/AttributeParser.cpp

844

Accident?

863

Would the crash be fixed by using getChecked here?

[mehdi_amini]

Remove spurious change

[mehdi_amini]

Don't use stringref, the API returns a string

[mehdi_amini]

mlir/lib/Parser/AttributeParser.cpp

863

Yes, but the error would be: elements literal must be a ranked tensor or vector type instead of invalid dialect namespace 'string with space'

[mehdi_amini]

mlir/lib/Parser/AttributeParser.cpp

863

Scratch that, it just works :)
Updated!

[mehdi_amini]

Use getChecked

[rriddle]

Nice

mlir/lib/Parser/AttributeParser.cpp

Attribute Parser::parseOpaqueElementsAttr(Type attrType) {
   consumeToken(Token::kw_opaque);
   if (parseToken(Token::less, "expected '<' after 'opaque'"))
     return nullptr;
 
   if (getToken().isNot(Token::string))
     return (emitError("expected dialect namespace"), nullptr);
 
   std::string name = getToken().getStringValue();
+  if (!Dialect::isValidNamespace(name))
+    return (emitError() << "invalid dialect namespace '" << name << "'",
+            nullptr);
   consumeToken(Token::string);
 
   if (parseToken(Token::comma, "expected ','"))
     return nullptr;
 
   Token hexTok = getToken();
   if (parseToken(Token::string, "elements hex string should start with '0x'") ||
       parseToken(Token::greater, "expected '>'"))
     return nullptr;
   auto type = parseElementsLiteralType(attrType);
   if (!type)
     return nullptr;
 
   std::string data;
   if (parseElementAttrHexValues(*this, hexTok, data))
     return nullptr;
   return OpaqueElementsAttr::get(builder.getStringAttr(name), type, data);
 }
 
 /// Shaped type for elements attribute.
 ///
 ///   elements-literal-type ::= vector-type | ranked-tensor-type
 ///
 /// This method also checks the type has static shape.
 ShapedType Parser::parseElementsLiteralType(Type type) {

mlir/test/IR/attribute.mlir

 // -----
 
 func @erroneous_fields() {
   // expected-error @+1 {{failed to satisfy constraint: DictionaryAttr with field(s): 'some_field', 'some_other_field' (each field having its own constraints)}}
   "test.struct_attr"() {the_struct_attr = {some_field = 1 : i8, some_other_field = 1}} : () -> ()
   return
 }
 
+// -----
+
+// expected-error @+1 {{invalid dialect namespace 'string with space'}}
+#invalid_dialect = opaque<"string with space", "0xDEADBEEF"> : i32