bugzilla 4003 The result changes only with the order of source files.

src/declaration.c

@@ -754,6 +754,9 @@ void VarDeclaration::semantic(Scope *sc)
         else
             type = init->inferType(sc);
 
+//printf("test2: %s, %s, %s\n", toChars(), type->toChars(), type->deco);
+//      type = type->semantic(loc, sc);
+
         inuse--;
         inferred = 1;
 

src/expression.c

@@ -5277,8 +5277,8 @@ Expression *IsExp::semantic(Scope *sc)
          * is(targ : tspec)
          */
         tspec = tspec->semantic(loc, sc);
-        //printf("targ  = %s\n", targ->toChars());
-        //printf("tspec = %s\n", tspec->toChars());
+        //printf("targ  = %s, %s\n", targ->toChars(), targ->deco);
+        //printf("tspec = %s, %s\n", tspec->toChars(), tspec->deco);
         if (tok == TOKcolon)
         {   if (targ->implicitConvTo(tspec))
                 goto Lyes;
@@ -5303,11 +5303,11 @@ Expression *IsExp::semantic(Scope *sc)
         if (sc->sd)
             s->addMember(sc, sc->sd, 1);
     }
-//printf("Lyes\n");
+    //printf("Lyes\n");
     return new IntegerExp(loc, 1, Type::tbool);
 
 Lno:
-//printf("Lno\n");
+    //printf("Lno\n");
     return new IntegerExp(loc, 0, Type::tbool);
 
 Lerr:
@@ -6429,7 +6429,27 @@ Expression *DotTemplateInstanceExp::semantic(Scope *sc)
         Dsymbol *s = ti->inst->toAlias();
         Declaration *v = s->isDeclaration();
         if (v)
-        {   e = new DotVarExp(loc, eleft, v);
+        {
+            /* Fix for Bugzilla 4003
+             * The problem is a class template member function v returning a reference to the same
+             * type as the enclosing template instantiation. This results in a nested instantiation,
+             * which of course gets short circuited. The return type then gets set to
+             * the template instance type before instantiation, rather than after.
+             * We can detect this by the deco not being set. If so, go ahead and retry
+             * the return type semantic.
+             * The offending code is the return type from std.typecons.Tuple.slice:
+             *    ref Tuple!(Types[from .. to]) slice(uint from, uint to)()
+             *    {
+             *        return *cast(typeof(return) *) &(field[from]);
+             *    }
+             * and this line from the following unittest:
+             *    auto s = a.slice!(1, 3);
+             * where s's type wound up not having semantic() run on it.
+             */
+            if (v->type && !v->type->deco)
+                v->type = v->type->semantic(v->loc, sc);
+
+            e = new DotVarExp(loc, eleft, v);
             e = e->semantic(sc);
             return e;
         }

src/func.c

@@ -137,7 +137,9 @@ void FuncDeclaration::semantic(Scope *sc)
     if (semanticRun >= PASSsemanticdone)
     {
         if (!parent->isClassDeclaration())
+        {
             return;
+        }
         // need to re-run semantic() in order to set the class's vtbl[]
     }
     else
@@ -2314,12 +2316,12 @@ AggregateDeclaration *FuncDeclaration::isMember2()
 //printf("\ts = '%s', parent = '%s', kind = %s\n", s->toChars(), s->parent->toChars(), s->parent->kind());
         ad = s->isMember();
         if (ad)
-{   //printf("test4\n");
+{
             break;
 }
         if (!s->parent ||
             (!s->parent->isTemplateInstance()))
-{   //printf("test5\n");
+{
             break;
 }
     }

src/mtype.c

@@ -7689,7 +7689,8 @@ Type *TypeSlice::semantic(Loc loc, Scope *sc)
         args->push(arg);
     }
 
-    return new TypeTuple(args);
+    Type *t = new TypeTuple(args)->semantic(loc, sc);
+    return t;
 }
 
 void TypeSlice::resolve(Loc loc, Scope *sc, Expression **pe, Type **pt, Dsymbol **ps)

src/template.c

@@ -3569,7 +3569,7 @@ void TemplateInstance::semantic(Scope *sc)
 
 void TemplateInstance::semantic(Scope *sc, Expressions *fargs)
 {
-    //printf("TemplateInstance::semantic('%s', this=%p)\n", toChars(), this);
+    //printf("TemplateInstance::semantic('%s', this=%p, gag = %d)\n", toChars(), this, global.gag);
     if (global.errors && name != Id::AssociativeArray)
     {
         //printf("not instantiating %s due to %d errors\n", toChars(), global.errors);