Fix mangling of @in_cxx

'C' is already taken by @convention(c).

Author: ahatanaka

docs/ABI/Mangling.rst

@@ -867,7 +867,7 @@ mangled in to disambiguate.
   PARAM-CONVENTION ::= 'l'                   // indirect inout
   PARAM-CONVENTION ::= 'b'                   // indirect inout aliasable
   PARAM-CONVENTION ::= 'n'                   // indirect in guaranteed
-  PARAM-CONVENTION ::= 'C'                   // indirect in C++
+  PARAM-CONVENTION ::= 'X'                   // indirect in C++
   PARAM-CONVENTION ::= 'x'                   // direct owned
   PARAM-CONVENTION ::= 'y'                   // direct unowned
   PARAM-CONVENTION ::= 'g'                   // direct guaranteed

lib/AST/ASTMangler.cpp

@@ -1137,7 +1137,7 @@ static char getParamConvention(ParameterConvention conv) {
     case ParameterConvention::Indirect_Inout: return 'l';
     case ParameterConvention::Indirect_InoutAliasable: return 'b';
     case ParameterConvention::Indirect_In_Guaranteed: return 'n';
-    case ParameterConvention::Indirect_In_CXX: return 'C';
+    case ParameterConvention::Indirect_In_CXX: return 'X';
     case ParameterConvention::Direct_Owned: return 'x';
     case ParameterConvention::Direct_Unowned: return 'y';
     case ParameterConvention::Direct_Guaranteed: return 'g';

lib/Demangling/Demangler.cpp

@@ -2160,7 +2160,7 @@ NodePointer Demangler::demangleImplParamConvention(Node::Kind ConvKind) {
     case 'l': attr = "@inout"; break;
     case 'b': attr = "@inout_aliasable"; break;
     case 'n': attr = "@in_guaranteed"; break;
-    case 'C': attr = "@in_cxx"; break;
+    case 'X': attr = "@in_cxx"; break;
     case 'x': attr = "@owned"; break;
     case 'g': attr = "@guaranteed"; break;
     case 'e': attr = "@deallocating"; break;

lib/Demangling/Remangler.cpp

@@ -2106,7 +2106,7 @@ ManglingError Remangler::mangleImplFunctionType(Node *node, unsigned depth) {
                 .Case("@inout", 'l')
                 .Case("@inout_aliasable", 'b')
                 .Case("@in_guaranteed", 'n')
-                .Case("@in_cxx", 'C')
+                .Case("@in_cxx", 'X')
                 .Case("@in_constant", 'c')
                 .Case("@owned", 'x')
                 .Case("@guaranteed", 'g')

test/Demangle/Inputs/manglings.txt

@@ -473,3 +473,4 @@ $sSRyxG15Synchronization19AtomicRepresentableABRi0_zrlMc ---> protocol conforman
 $sSRyxG15Synchronization19AtomicRepresentableABRi1_zrlMc ---> protocol conformance descriptor for < where A: ~Swift.<bit 2>> Swift.UnsafeBufferPointer<A> : Synchronization.AtomicRepresentable in Synchronization
 
 $s23variadic_generic_opaque2G2VyAA2S1V_AA2S2VQPGAA1PHPAeA1QHPyHC_AgaJHPyHCHX_HC ---> concrete protocol conformance variadic_generic_opaque.G2<Pack{variadic_generic_opaque.S1, variadic_generic_opaque.S2}> to protocol conformance ref (type's module) variadic_generic_opaque.P with conditional requirements: (pack protocol conformance (concrete protocol conformance variadic_generic_opaque.S1 to protocol conformance ref (type's module) variadic_generic_opaque.Q, concrete protocol conformance variadic_generic_opaque.S2 to protocol conformance ref (type's module) variadic_generic_opaque.Q))
+$sxq_IyXd_D ---> @callee_unowned (@in_cxx A) -> (@unowned B)