4820 – Regression(1.058, 2.044) in DStress caused by changeset 452

Changeset 452 that was used to solve bug 2935 causes 4 regressions in the DStress test suite. The tests that now fail are the following:
run/l/lazy_02_A.d
run/l/lazy_02_B.d
run/l/lazy_02_C.d
run/l/lazy_02_D.d
The first one, for example is:
bool nextis(void delegate() dgpositive = {}) {
	return true;
}
bool looping(lazy bool condition) {
	return true;
}
int main() {
	looping(nextis());
	return 0;
}
and when compiled with DMD1.063 yields:
test.d(1): Error: cannot inline default argument __dgliteral1

Thanks for the superb bug report!
Reduced test case shows it's nothing to do with lazy:
void nextis(void delegate() dg = {}) {}
void main() {
 nextis();
}
This is failing because function/delegate literals cannot be inlined. Prior to svn 452, that wasn't being checked in the special case where they were default parameters. Until bug 2935 was fixed, default values were created in the same scope as the function declaration. That was a disaster for structs, but might be OK for function literals -- not sure. Here's an example which used to compile, but now fails, which never used global scope.
void main() {
 int x = 27;
 int nextis(int delegate() dg = { return x; }) { return dg(); }
 ++x;
 assert(nextis() == 28);
}

*** Issue 4304 has been marked as a duplicate of this issue. ***

Although this particular case used to work, it was very fragile.
Calling nextis() directly from main() never worked.
This whole feature probably won't correctly until delegate literals can be inlined.

Commit pushed to master at https://github.com/D-Programming-Language/dmd
https://github.com/D-Programming-Language/dmd/commit/06e98272f690cf79444b797d2de021ee7eb4a186
fix Issue 4820 - Regression(1.058, 2.044) in DStress caused by changeset 452

Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd
https://github.com/D-Programming-Language/dmd/commit/415e48ac4703ffab94cd6ce5a3211625099c637a
fix Issue 4820 - Regression(1.058, 2.044) in DStress caused by changeset 452