1 files changed, 49 insertions, 13 deletions

diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 130cd9f206..e81e0863b5 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2442,12 +2442,12 @@ void Parser::ParseSpecifierQualifierList(DeclSpec &DS, AccessSpecifier AS,
       Diag(DS.getInlineSpecLoc(), diag::err_typename_invalid_functionspec);
     if (DS.isVirtualSpecified())
       Diag(DS.getVirtualSpecLoc(), diag::err_typename_invalid_functionspec);
-    if (DS.isExplicitSpecified())
+    if (DS.hasExplicitSpecifier())
       Diag(DS.getExplicitSpecLoc(), diag::err_typename_invalid_functionspec);
     DS.ClearFunctionSpecs();
   }
 
-  // Issue diagnostic and remove constexpr specfier if present.
+  // Issue diagnostic and remove constexpr specifier if present.
   if (DS.isConstexprSpecified() && DSC != DeclSpecContext::DSC_condition) {
     Diag(DS.getConstexprSpecLoc(), diag::err_typename_invalid_constexpr);
     DS.ClearConstexprSpec();
@@ -2962,9 +2962,13 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
   while (1) {
     bool isInvalid = false;
     bool isStorageClass = false;
+    bool isAlreadyConsumed = false;
     const char *PrevSpec = nullptr;
     unsigned DiagID = 0;
 
+    // This value need to be set when isAlreadyConsumed is set to true.
+    SourceLocation RangeEnd;
+
     // HACK: MSVC doesn't consider _Atomic to be a keyword and its STL
     // implementation for VS2013 uses _Atomic as an identifier for one of the
     // classes in <atomic>.
@@ -3515,9 +3519,34 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
         isInvalid = DS.setFunctionSpecVirtual(Loc, PrevSpec, DiagID);
       }
       break;
-    case tok::kw_explicit:
-      isInvalid = DS.setFunctionSpecExplicit(Loc, PrevSpec, DiagID);
+    case tok::kw_explicit: {
+      SourceLocation ExplicitLoc = Loc;
+      SourceLocation CloseParenLoc;
+      ExplicitSpecifier ExplicitSpec(nullptr, ExplicitSpecKind::ResolvedTrue);
+      isAlreadyConsumed = true;
+      RangeEnd = ExplicitLoc;
+      ConsumeToken(); // kw_explicit
+      if (Tok.is(tok::l_paren)) {
+        if (getLangOpts().CPlusPlus2a) {
+          ExprResult ExplicitExpr(static_cast<Expr *>(nullptr));
+          BalancedDelimiterTracker Tracker(*this, tok::l_paren);
+          Tracker.consumeOpen();
+          ExplicitExpr = ParseConstantExpression();
+          RangeEnd = Tok.getLocation();
+          if (ExplicitExpr.isUsable()) {
+            CloseParenLoc = Tok.getLocation();
+            Tracker.consumeClose();
+            ExplicitSpec =
+                Actions.ActOnExplicitBoolSpecifier(ExplicitExpr.get());
+          } else
+            Tracker.skipToEnd();
+        } else
+          Diag(Tok.getLocation(), diag::warn_cxx2a_compat_explicit_bool);
+      }
+      isInvalid = DS.setFunctionSpecExplicit(ExplicitLoc, PrevSpec, DiagID,
+                                             ExplicitSpec, CloseParenLoc);
       break;
+    }
     case tok::kw__Noreturn:
       if (!getLangOpts().C11)
         Diag(Loc, diag::ext_c11_noreturn);
@@ -3861,25 +3890,32 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       // If a type specifier follows, it will be diagnosed elsewhere.
       continue;
     }
+
+    assert(!isAlreadyConsumed || RangeEnd != SourceLocation() &&
+                                     "both or neither of isAlreadyConsumed and "
+                                     "RangeEnd needs to be set");
+    DS.SetRangeEnd(isAlreadyConsumed ? RangeEnd : Tok.getLocation());
+
     // If the specifier wasn't legal, issue a diagnostic.
     if (isInvalid) {
       assert(PrevSpec && "Method did not return previous specifier!");
       assert(DiagID);
 
       if (DiagID == diag::ext_duplicate_declspec ||
-          DiagID == diag::ext_warn_duplicate_declspec)
-        Diag(Tok, DiagID)
-          << PrevSpec << FixItHint::CreateRemoval(Tok.getLocation());
+          DiagID == diag::ext_warn_duplicate_declspec ||
+          DiagID == diag::err_duplicate_declspec)
+        Diag(Loc, DiagID) << PrevSpec
+                          << FixItHint::CreateRemoval(
+                                 SourceRange(Loc, DS.getEndLoc()));
       else if (DiagID == diag::err_opencl_unknown_type_specifier) {
-        Diag(Tok, DiagID) << getLangOpts().OpenCLCPlusPlus
-            << getLangOpts().getOpenCLVersionTuple().getAsString()
-            << PrevSpec << isStorageClass;
+        Diag(Loc, DiagID) << getLangOpts().OpenCLCPlusPlus
+                          << getLangOpts().getOpenCLVersionTuple().getAsString()
+                          << PrevSpec << isStorageClass;
       } else
-        Diag(Tok, DiagID) << PrevSpec;
+        Diag(Loc, DiagID) << PrevSpec;
     }
 
-    DS.SetRangeEnd(Tok.getLocation());
-    if (DiagID != diag::err_bool_redeclaration)
+    if (DiagID != diag::err_bool_redeclaration && !isAlreadyConsumed)
       // After an error the next token can be an annotation token.
       ConsumeAnyToken();