Fix re-mangling of function specialization constant strings which start with a digit.

Author: eeckstein

lib/Basic/Remangler.cpp

@@ -830,9 +830,17 @@ void Remangler::mangleFunctionSignatureSpecialization(Node *node) {
         case FunctionSigSpecializationParamKind::ConstantPropGlobal:
           mangleIdentifier(Param->getChild(1).get());
           break;
-        case FunctionSigSpecializationParamKind::ConstantPropString:
-          mangleIdentifier(Param->getChild(2).get());
+        case FunctionSigSpecializationParamKind::ConstantPropString: {
+          NodePointer TextNd = Param->getChild(2);
+          StringRef Text = TextNd->getText();
+          if (Text.size() > 0 && (isDigit(Text[0]) || Text[0] == '_')) {
+            std::string Buffer = "_";
+            Buffer.append(Text.data(), Text.size());
+            TextNd = NodeFactory::create(Node::Kind::Identifier, Buffer);
+          }
+          mangleIdentifier(TextNd.get());
           break;
+        }
         case FunctionSigSpecializationParamKind::ClosureProp:
           mangleIdentifier(Param->getChild(1).get());
           for (unsigned i = 2, e = Param->getNumChildren(); i != e; ++i) {

test/Demangle/Inputs/manglings.txt

@@ -239,5 +239,6 @@ _TFVFE15nested_genericsSS3fooFT_T_L_6CheeseCfT8materialx_GS0_x_ ---> (extension
 _TTWOE5imojiCSo5Imoji14ImojiMatchRankS_9RankValueS_FS2_g9rankValueqq_Ss16RawRepresentable8RawValue ---> _TTWOE5imojiCSo5Imoji14ImojiMatchRankS_9RankValueS_FS2_g9rankValueqq_Ss16RawRepresentable8RawValue
 _TtFzas4VoidGC16FusionXBaseUtils6FutureQq_ZFVS_7Futures6futureurFFzT_GS0_x_GS0_x__ ---> _TtFzas4VoidGC16FusionXBaseUtils6FutureQq_ZFVS_7Futures6futureurFFzT_GS0_x_GS0_x__
 _T0s17MutableCollectionP1asAARzs012RandomAccessB0RzsAA11SubSequences013BidirectionalB0PRpzsAdHRQlE06rotatecD05Indexs01_A9IndexablePQzAM15shiftingToStart_tFAJs01_J4BasePQzAQcfU_ ---> (extension in a):Swift.MutableCollection<A where A: Swift.MutableCollection, A: Swift.RandomAccessCollection, A.SubSequence: Swift.MutableCollection, A.SubSequence: Swift.RandomAccessCollection>.(rotateRandomAccess (shiftingToStart : A.Index) -> A.Index).(closure #1)
+_T03foo4_123ABTf3psbpsb_n ---> function signature specialization <Arg[0] = [Constant Propagated String : u8'123'], Arg[1] = [Constant Propagated String : u8'123']> of foo
 _T04main5innerys5Int32Vz_yADctF25closure_with_box_argumentxz_Bi32__lXXTf1nc_n ---> function signature specialization <Arg[1] = [Closure Propagated : closure_with_box_argument, Argument Types : [<A> { var A } <Builtin.Int32>]> of main.inner (inout Swift.Int32, (Swift.Int32) -> ()) -> ()