Don't crash on duplicate keys in dictionary attrs.

[silvas]

Summary

Fixes http://llvm.org/PR45704

[rriddle]

mlir/lib/Parser/Parser.cpp

1713

Do this during parsing above to give better error location and avoid the need to iterate.

[silvas]

Done.

[rriddle]

mlir/lib/Parser/Parser.cpp

1679

nit: uniquifier sounds weird, can we just do something like "usedNames"?

[silvas]

Update name.

mlir/lib/Parser/Parser.cpp

 ///                    | `{` attribute-entry (`,` attribute-entry)* `}`
 ///   attribute-entry ::= (bare-id | string-literal) `=` attribute-value
 ///
 ParseResult
 Parser::parseAttributeDict(SmallVectorImpl<NamedAttribute> &attributes) {
   if (parseToken(Token::l_brace, "expected '{' in attribute dictionary"))
     return failure();
 
+  llvm::SmallDenseSet<Identifier> seenKeys;
   auto parseElt = [&]() -> ParseResult {
     // The name of an attribute can either be a bare identifier, or a string.
     Optional<Identifier> nameId;
     if (getToken().is(Token::string))
       nameId = builder.getIdentifier(getToken().getStringValue());
     else if (getToken().isAny(Token::bare_identifier, Token::inttype) ||
              getToken().isKeyword())
       nameId = builder.getIdentifier(getTokenSpelling());
     else
       return emitError("expected attribute name");
+    if (!seenKeys.insert(*nameId).second)
+      return emitError("duplicate key in dictionary attribute");
     consumeToken();
 
     // Try to parse the '=' for the attribute value.
     if (!consumeIf(Token::equal)) {
       // If there is no '=', we treat this as a unit attribute.
       attributes.push_back({*nameId, builder.getUnitAttr()});
       return success();
     }
 
     auto attr = parseAttribute();
     if (!attr)
       return failure();
 
     attributes.push_back({*nameId, attr});
     return success();
   };
 
   if (parseCommaSeparatedListUntil(Token::r_brace, parseElt))
     return failure();
 
   return success();
 }
 
 /// Parse an extended attribute.
 ///
 ///   extended-attribute ::= (dialect-attribute | attribute-alias)
 ///   dialect-attribute  ::= `#` dialect-namespace `<` `"` attr-data `"` `>`
 ///   dialect-attribute  ::= `#` alias-name pretty-dialect-sym-body?
 ///   attribute-alias    ::= `#` alias-name
 ///

mlir/test/IR/invalid.mlir

 
 func @really_large_bound() {
   "test.out_of_range_attribute"() {
     // expected-error @+1 {{integer constant out of range for attribute}}
     attr = 39614081257132168796771975168 : si96
   } : () -> ()
   return
 }
+
+// -----
+
+func @duplicate_dictionary_attr_key() {
+  // expected-error @+1 {{duplicate key in dictionary attribute}}
+  "foo.op"() {a, a} : () -> ()
+}