d: Fix ICE in in add_stack_var, at cfgexpand.cc:476

The type that triggers the ICE never got completed by the semantic
analysis pass.  Checking for size forces it to be done, or issue a
compile-time error.

	PR d/106555

gcc/d/ChangeLog:

	* d-target.cc (Target::isReturnOnStack): Check for return type size.

gcc/testsuite/ChangeLog:

	* gdc.dg/imports/pr106555.d: New test.
	* gdc.dg/pr106555.d: New test.

(cherry picked from commit 4b0253b019)

gcc/d/d-target.cc

@@ -464,6 +464,8 @@ Target::isReturnOnStack (TypeFunction *tf, bool)
     return false;
 
   Type *tn = tf->next->toBasetype ();
+  if (tn->size () == SIZE_INVALID)
+    return false;
 
   return (tn->ty == TY::Tstruct || tn->ty == TY::Tsarray);
 }

gcc/testsuite/gdc.dg/imports/pr106555.d

@@ -0,0 +1,10 @@
+module imports.pr106555;
+struct S106555
+{
+    int[] f106555;
+    int max106555;
+    this(int)
+    {
+        f106555.length = max106555;
+    }
+}

gcc/testsuite/gdc.dg/pr106555.d

@@ -0,0 +1,4 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106555
+// { dg-do compile }
+// { dg-additional-options "-O2" }
+// { dg-additional-sources "imports/pr106555.d" }