More conservative fix for issue 12900 - Wrong code in IfStatement condition Expression

src/e2ir.c

@@ -3215,6 +3215,17 @@ elem *toElem(Expression *e, IRState *irs)
                 dve->error("%s is not a field, but a %s", dve->var->toChars(), dve->var->kind());
             }
 
+            // Bugzilla 12900
+            Type *txb = dve->type->toBasetype();
+            Type *tyb = v->type->toBasetype();
+            if (txb->ty == Tvector) txb = ((TypeVector *)txb)->basetype;
+            if (tyb->ty == Tvector) tyb = ((TypeVector *)tyb)->basetype;
+#if DEBUG
+            if (txb->ty != tyb->ty)
+                printf("[%s] dve = %s, dve->type = %s, v->type = %s\n", dve->loc.toChars(), dve->toChars(), dve->type->toChars(), v->type->toChars());
+#endif
+            assert(txb->ty == tyb->ty);
+
             elem *e = dve->e1->toElem(irs);
             Type *tb1 = dve->e1->type->toBasetype();
             if (tb1->ty != Tclass && tb1->ty != Tpointer)

src/optimize.c

@@ -322,7 +322,7 @@ Expression *Expression_optimize(Expression *e, int result, bool keepLvalue)
                 Expression *ex = ((PtrExp *)e->e1)->e1;
                 if (e->type->equals(ex->type))
                     ret = ex;
-                else
+                else if (e->type->toBasetype()->immutableOf()->equals(ex->type->toBasetype()->immutableOf()))
                 {
                     ret = ex->copy();
                     ret->type = e->type;
@@ -379,7 +379,7 @@ Expression *Expression_optimize(Expression *e, int result, bool keepLvalue)
                 Expression *ex = ((AddrExp *)e->e1)->e1;
                 if (e->type->equals(ex->type))
                     ret = ex;
-                else if (ex->type->implicitConvTo(e->type) >= MATCHconst)
+                else if (e->type->toBasetype()->immutableOf()->equals(ex->type->toBasetype()->immutableOf()))
                 {
                     ret = ex->copy();
                     ret->type = e->type;

src/s2ir.c

@@ -157,7 +157,7 @@ class S2irVisitor : public Visitor
         elem *e;
         Blockx *blx = irs->blx;
 
-        //printf("IfStatement::toIR('%s')\n", condition->toChars());
+        //printf("IfStatement::toIR('%s')\n", s->condition->toChars());
 
         IRState mystate(irs, s);
 

test/runnable/xtest46.d

@@ -6914,6 +6914,21 @@ void test12498()
     string x = t;
 }
 
+/***************************************************/
+// 12900
+
+struct A12900
+{
+    char[1] b;
+}
+
+void test12900()
+{
+    A12900 c;
+    if (*c.b.ptr)
+        return;
+}
+
 /***************************************************/
 // 12937