3261 – compiler crash with mixin and forward reference (Issue 402 and 784)

this is slightly different code from Issue 402 and Issue 784, but it causes the compiler to freeze in DMD 1.046 and 2.032:
> dmd -c Conflicts.d
Conflicts.d(12): Error: mixin Conflicts.foo.BadImpl!(uint,Mix1) cannot resolve forward reference
Conflicts.d(12): Error: mixin Conflicts.foo.BadImpl!(uint,Mix1) cannot resolve forward reference
--- Conflicts.d ----
template BadImpl(T, alias thename)
{
 void a_bad_idea(T t)
 {
 thename.a_bad_idea(t);
 }
}
class foo
{
 mixin BadImpl!(uint,Mix1) Mix1;
}
int main()
{
 return 0;
}

Here's a superficial patch. If an error occurs while determining the arguments, it shouldn't try to determine which template is intended.
Patch: template.c, line 4542.
--------
 // Run semantic on each argument, place results in tiargs[]
+ int olderrors = global.errors;
 semanticTiargs(sc);
+ if (global.errors != olderrors) return; // Quit immediately if error occurs in argument
 tempdecl = findBestMatch(sc);
 if (!tempdecl)
 {	inst = this;
	return;		// error recovery
 }

I guess this counts as an actual forward reference bug, given that Mix1 is kind-of a forward reference....
(This seems to be a variation of CRTP.)
(In reply to comment #0)
> this is slightly different code from Issue 402 and Issue 784, but 
> it causes the compiler to freeze in DMD 1.046 and 2.032:
Uh, 2.032 doesn't seem to have been released yet.

Fixed dmd 1.049 and 2.034