Don't allocate front-end Strings on C++ heap

If the GC is enabled (-lowmem), it must know about those Array instances,
so that the GC-allocated array of pointers and referenced GC-allocated
strings are kept alive.

dmd/ldcbindings.d

@@ -9,6 +9,7 @@
 
 module dmd.ldcbindings;
 
+import dmd.arraytypes : Strings;
 import dmd.expression;
 import dmd.globals;
 import dmd.identifier;
@@ -72,3 +73,5 @@ mixin(factory!Expression);
 mixin(factory!InlineAsmStatement);
 mixin(factory!TypeDelegate);
 mixin(factory!TypeIdentifier);
+
+Strings* createStrings() { return new Strings(); }

dmd/ldcbindings.h

@@ -44,6 +44,8 @@ InlineAsmStatement *createInlineAsmStatement(const Loc &loc, Token *tokens);
 TypeDelegate *createTypeDelegate(Type *t);
 TypeIdentifier *createTypeIdentifier(const Loc &loc, Identifier *ident);
 
+Strings *createStrings();
+
 // Structs
 //Loc createLoc(const char * filename, uint linnum, uint charnum);
 

driver/main.cpp

@@ -14,6 +14,7 @@
 #include "dmd/identifier.h"
 #include "dmd/hdrgen.h"
 #include "dmd/json.h"
+#include "dmd/ldcbindings.h"
 #include "dmd/mars.h"
 #include "dmd/module.h"
 #include "dmd/mtype.h"
@@ -159,7 +160,7 @@ void processVersions(std::vector<std::string> &list, const char *type,
       char *cstr = mem.xstrdup(value);
       if (Identifier::isValidIdentifier(cstr)) {
         if (!globalIDs)
-          globalIDs = new Strings();
+          globalIDs = createStrings();
         globalIDs->push(cstr);
         continue;
       } else {

gen/cl_helpers.cpp

@@ -10,6 +10,7 @@
 #include "gen/cl_helpers.h"
 
 #include "dmd/errors.h"
+#include "dmd/ldcbindings.h"
 #include "dmd/root/rmem.h"
 #include "dmd/root/root.h"
 #include <algorithm>
@@ -65,7 +66,7 @@ void StringsAdapter::push_back(const char *cstr) {
   }
 
   if (!*arrp) {
-    *arrp = new Strings;
+    *arrp = createStrings();
   }
   (*arrp)->push(mem.xstrdup(cstr));
 }