Only doing pattern matching if token is not a keywork or if is a possible identifier

Author: LucianoPAlmeida

lib/Parse/ParseDecl.cpp

@@ -5767,11 +5767,13 @@ Parser::parseDeclEnumCase(ParseDeclOptions Flags,
       SourceLoc TokLoc = Tok.getLoc();
       StringRef TokText = Tok.getText();
 
-      // For recovery, see if the user typed something resembling a switch
-      // "case" label.
-      llvm::SaveAndRestore<decltype(InVarOrLetPattern)>
-      T(InVarOrLetPattern, Parser::IVOLP_InMatchingPattern);
-      parseMatchingPattern(/*isExprBasic*/false);
+      if (!NameIsKeyword || Tok.isIdentifierOrUnderscore()) {
+        // For recovery, see if the user typed something resembling a switch
+        // "case" label.
+        llvm::SaveAndRestore<decltype(InVarOrLetPattern)>
+        T(InVarOrLetPattern, Parser::IVOLP_InMatchingPattern);
+        parseMatchingPattern(/*isExprBasic*/false);
+      }
 
       if (consumeIf(tok::colon)) {
         diagnose(CaseLoc, diag::case_outside_of_switch, "case");

test/Parse/enum.swift

@@ -115,8 +115,8 @@ enum Recovery2 {
 enum Recovery3 {
   case UE2(Void): // expected-error {{'case' label can only appear inside a 'switch' statement}}
 }
-enum Recovery4 { 
-  case Self Self // expected-error {{keyword 'Self' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{8-12=`Self`}}
+enum Recovery4 { // expected-note {{in declaration of 'Recovery4'}}
+  case Self Self // expected-error {{keyword 'Self' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{8-12=`Self`}} expected-error {{consecutive declarations on a line must be separated by ';'}} {{12-12=;}} expected-error {{expected declaration}}
 }
 enum Recovery5 {
   case .UE3 // expected-error {{extraneous '.' in enum 'case' declaration}} {{8-9=}}
@@ -556,10 +556,10 @@ enum SE0155 {
 // SR-11261
 enum SR11261 {
   case identifier
-  case operator // expected-error {{keyword 'operator' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{8-16=`operator`}} expected-error {{expected pattern}}
+  case operator // expected-error {{keyword 'operator' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{8-16=`operator`}}
   case identifier2
 }
 
 enum SR11261_1 {
-  case a, b, c, func, d // expected-error {{keyword 'func' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{17-21=`func`}} expected-error {{expected pattern}}
+  case a, b, c, func, d // expected-error {{keyword 'func' cannot be used as an identifier here}} expected-note {{if this name is unavoidable, use backticks to escape it}} {{17-21=`func`}}
 }