5086 – Regression(1.061): Stack overflow with recursive alias declaration

This is dstress nocompile/a/alias_30_J.d and nocompile/a/alias_30_K.d
---
alias a b;
alias b a;
 	
b x;
---
bug.d(7): Error: alias test0.a recursive alias declaration
Stack overflow
---
D1 only, worked in 1.061.
Doesn't happen if DMD is compiled in debug mode.

And this is nocompile/c/const_34_A.d, which is also failing. In total, 5 dstress cases are now hitting a stack overflow because of this bug. D2 is not affected.
const auto a = a;

Regression was introduced in 1.061 by the fix to bug 4016, in expression.c, DsymbolExp::semantic()
 //printf("Identifier '%s' is a variable, type '%s'\n", toChars(),
v->type->toChars());
 if (!type)
 {
+ if (!v->type && v->scope)
+ v->semantic(v->scope);
 type = v->type;
 if (!v->type)
 { error("forward reference of %s %s", v->kind(), v->toChars());
The code doesn't fail on D2, because v->scope is not set on D2.

*** Issue 4794 has been marked as a duplicate of this issue. ***

*** Issue 4892 has been marked as a duplicate of this issue. ***

Created attachment 945 [details] 
issue5086
Patch for D1 - I'm not entirely sure on the correctness of the first hunk.

Created attachment 946 [details] 
issue5086
Yep, that questionable change broke tango build - should now be sorted.

https://github.com/D-Programming-Language/dmd/commit/63c06ad29f5ef81a6a53d8b6eace3660912894b4