Allow unbracketed logical constant in IF and WHILE statementsbenbrewer/if-logical-const

2 files changed, 37 insertions, 25 deletions

diff --git a/include/flang/Parse/Parser.h b/include/flang/Parse/Parser.h
index b498f6054d..eb6156808c 100644
--- a/include/flang/Parse/Parser.h
+++ b/include/flang/Parse/Parser.h
@@ -484,7 +484,7 @@ private:
   StmtResult ParseElseIfStmt();
   StmtResult ParseElseStmt();
   StmtResult ParseEndIfStmt();
-  ExprResult ParseExpectedConditionExpression(const char *DiagAfter);
+  ExprResult ParseExpectedConditionExpression(const char *DiagAfter, bool *Failed = NULL);
 
   StmtResult ParseDoStmt();
   StmtResult ParseDoWhileStmt(bool isDo);
diff --git a/lib/Parse/ParseExec.cpp b/lib/Parse/ParseExec.cpp
index 7ac3e1afdf..9d070f2814 100644
--- a/lib/Parse/ParseExec.cpp
+++ b/lib/Parse/ParseExec.cpp
@@ -336,29 +336,44 @@ Parser::StmtResult Parser::ParseGotoStmt() {
 ///     if-stmt :=
 ///       IF(scalar-logic-expr) action-stmt
 
-ExprResult Parser::ParseExpectedConditionExpression(const char *DiagAfter) {
-  if (!ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after,
-      DiagAfter))
-    return ExprError();
-  ExprResult Condition = ParseExpectedFollowupExpression("(");
-  if(Condition.isInvalid()) return Condition;
-  if (!ExpectAndConsume(tok::r_paren))
-    return ExprError();
+ExprResult Parser::ParseExpectedConditionExpression(const char *DiagAfter, bool *Failed) {
+  ExprResult Condition;
+  if (IsPresent(tok::logical_literal_constant)) {
+    Condition = ParseExpectedFollowupExpression(DiagAfter);
+  } else {
+    if (!ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after,
+        DiagAfter)) {
+      if (Failed)
+        *Failed = true;
+      return ExprError();
+    }
+
+    Condition = ParseExpectedFollowupExpression("(");
+    if(Condition.isInvalid() && !SkipUntil(tok::r_paren, true, true)) {
+      if (Failed)
+        *Failed = true;
+      return Condition;
+    }
+
+    if (!ExpectAndConsume(tok::r_paren)) {
+      if (Failed)
+        *Failed = true;
+      return ExprError();
+    }
+  }
+
+  if (Failed)
+    *Failed = false;
   return Condition;
 }
 
 Parser::StmtResult Parser::ParseIfStmt() {
   auto Loc = ConsumeToken();
 
-  ExprResult Condition;
-  if (!ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after, "IF"))
+  bool BadCondition = false;
+  ExprResult Condition = ParseExpectedConditionExpression("IF", &BadCondition);
+  if (BadCondition)
     goto error;
-  Condition = ParseExpectedFollowupExpression("(");
-  if(Condition.isInvalid()) {
-    if(!SkipUntil(tok::r_paren, true, true))
-      goto error;
-  }
-  if (!ExpectAndConsume(tok::r_paren)) goto error;
 
   if(Features.FixedForm && !Tok.isAtStartOfStatement())
     ReLexAmbiguousIdentifier(FixedFormAmbiguities.getMatcherForKeywordsAfterIF());
@@ -387,15 +402,12 @@ error:
 // FIXME: fixed-form THENconstructname
 Parser::StmtResult Parser::ParseElseIfStmt() {
   auto Loc = ConsumeToken();
-  ExprResult Condition;
-  if (!ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after, "ELSE IF"))
+
+  bool BadCondition = false;
+  ExprResult Condition = ParseExpectedConditionExpression("ELSE IF", &BadCondition);
+  if (BadCondition)
     goto error;
-  Condition = ParseExpectedFollowupExpression("(");
-  if(Condition.isInvalid()) {
-    if(!SkipUntil(tok::r_paren, true, true))
-      goto error;
-  }
-  if (!ExpectAndConsume(tok::r_paren)) goto error;
+
   if (!ExpectAndConsumeFixedFormAmbiguous(tok::kw_THEN, diag::err_expected_kw, "THEN"))
     goto error;
   ParseTrailingConstructName();