d: Fix ICE in setValue, at d/dmd/dinterpret.c:7013

Backports ICE fix from upstream.  When casting null to integer or real,
instead of painting the type on the NullExp, we emplace an
IntegerExp/RealExp with the value zero.  Same as when casting from
NullExp to bool.

Reviewed-on: https://github.com/dlang/dmd/pull/13172

	PR d/110511

gcc/d/ChangeLog:

	* dmd/dinterpret.c (Interpreter::visit (CastExp *)): Handle casting
	null to int or float.

gcc/testsuite/ChangeLog:

	* gdc.test/compilable/test21794.d: New test.

(cherry picked from commit 066385c918485d4cef5c243d3b0691193df382de)

2 files changed, 63 insertions, 1 deletions

diff --git a/gcc/d/dmd/dinterpret.c b/gcc/d/dmd/dinterpret.c
index 214a73cd8bb..51b4a7d1c48 100644
--- a/gcc/d/dmd/dinterpret.c
+++ b/gcc/d/dmd/dinterpret.c
@@ -5843,12 +5843,22 @@ public:
         }
         if (e->to->ty == Tsarray)
             e1 = resolveSlice(e1);
-        if (e->to->toBasetype()->ty == Tbool && e1->type->ty == Tpointer)
+        Type *tobt = e->to->toBasetype();
+        if (tobt->ty == Tbool && e1->type->ty == Tpointer)
         {
             new(pue) IntegerExp(e->loc, e1->op != TOKnull, e->to);
             result = pue->exp();
             return;
         }
+        else if (tobt->isTypeBasic() && e1->op == TOKnull)
+        {
+            if (tobt->isintegral())
+                new(pue) IntegerExp(e->loc, 0, e->to);
+            else if (tobt->isreal())
+                new(pue) RealExp(e->loc, CTFloat::zero, e->to);
+            result = pue->exp();
+            return;
+        }
         result = ctfeCast(pue, e->loc, e->type, e->to, e1);
     }
 
diff --git a/gcc/testsuite/gdc.test/compilable/test21794.d b/gcc/testsuite/gdc.test/compilable/test21794.d
new file mode 100644
index 00000000000..68e504bce56
--- /dev/null
+++ b/gcc/testsuite/gdc.test/compilable/test21794.d
@@ -0,0 +1,52 @@
+// https://issues.dlang.org/show_bug.cgi?id=21794
+/*
+TEST_OUTPUT:
+---
+0
+0u
+0L
+0LU
+0.0F
+0.0
+0.0L
+---
+*/
+
+bool fun(void* p) {
+    const x = cast(ulong)p;
+    return 1;
+}
+
+static assert(fun(null));
+
+T fun2(T)(void* p) {
+    const x = cast(T)p;
+    return x;
+}
+
+// These were an error before, they were returning a NullExp instead of IntegerExp/RealExp
+
+static assert(fun2!int(null)    == 0);
+static assert(fun2!uint(null)   == 0);
+static assert(fun2!long(null)   == 0);
+static assert(fun2!ulong(null)  == 0);
+static assert(fun2!float(null)  == 0);
+static assert(fun2!double(null) == 0);
+static assert(fun2!real(null)   == 0);
+
+// These were printing 'null' instead of the corresponding number
+
+const i = cast(int)null;
+const ui = cast(uint)null;
+const l = cast(long)null;
+const ul = cast(ulong)null;
+const f = cast(float)null;
+const d = cast(double)null;
+const r = cast(real)null;
+pragma(msg, i);
+pragma(msg, ui);
+pragma(msg, l);
+pragma(msg, ul);
+pragma(msg, f);
+pragma(msg, d);
+pragma(msg, r);