https://issues.dlang.org/show_bug.cgi?id=23781

          Issue ID: 23781
           Summary: [ICE] Segmentation Fault when taking the address of a
                    ref return at CTFE
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: pro.mathias.lang@gmail.com

```
struct Bar { int i; }
ref const(Bar) func1 (const return ref Bar b) { return b; }
immutable E1 = Bar();
enum E2 = &E1.func1();
```

```
Program received signal SIGSEGV, Segmentation fault.
0x00005555559ea2e0 in Interpreter::visit(AddrExp*) (this=0x7fffffffced0,
e=0x7ffff73366d0) at src/dmd/dinterpret.d:2039
2039                if (ve.var == istate.fd.vthis)
(gdb) bt
#0  0x00005555559ea2e0 in Interpreter::visit(AddrExp*) (this=0x7fffffffced0,
e=0x7ffff73366d0) at src/dmd/dinterpret.d:2039
#1  0x0000555555a6af16 in AddrExp::accept(Visitor*) (this=0x7ffff73366d0,
v=0x7fffffffced0) at src/dmd/expression.d:5359
#2  0x00005555559f8705 in
_D3dmd10dinterpret9interpretFPSQBd10expression8UnionExpCQCcQz10ExpressionPSQCvQCu10InterStateEQDoQDn8CTFEGoalZQCd
(
    goal=<incomplete type>, istate=0x0, e=0x7ffff73366d0, pue=0x7fffffffcf30)
at src/dmd/dinterpret.d:6552
#3  0x00005555559f875e in
_D3dmd10dinterpret9interpretFCQBc10expression10ExpressionPSQCfQCe10InterStateEQCyQCx8CTFEGoalZQCn
(
    goal=<incomplete type>, istate=0x0, e=0x7ffff73366d0) at
src/dmd/dinterpret.d:6562
#4  0x00005555559e49fb in
_D3dmd10dinterpret13ctfeInterpretFCQBh10expression10ExpressionZQBd
(e=0x7ffff73366d0) at src/dmd/dinterpret.d:101
#5  0x0000555555a61e19 in Expression::ctfeInterpret() (this=0x7ffff73366d0) at
src/dmd/expression.d:1683
#6  0x0000555555ac1afe in
_D3dmd7initsem19initializerSemanticRCQBj4init11InitializerPSQCg6dscope5ScopeKCQCy5mtype4TypeEQDnQCe13NeedInterpretZ8visitExpMFCQEvQDm14ExpInitializerZQEk
(__capture=0x7fffffffd2a0, i=0x7ffff7b06a60) at src/dmd/initsem.d:374
#7  0x0000555555ac38f8 in
_D3dmd7initsem19initializerSemanticRCQBj4init11InitializerPSQCg6dscope5ScopeKCQCy5mtype4TypeEQDnQCe13NeedInterpretZ5visit16VisitInitializerMFQEbZQEf
(__capture=0x7fffffffd2a0, init=0x7ffff7b06a60) at src/dmd/init.d-mixin-366:372
#8  0x0000555555ac0a7a in initializerSemantic(Initializer*, Scope*, Type*&,
NeedInterpret) (init=0x7ffff7b06a60, sc=0x7ffff73312f0,
    tx=@0x7ffff7b06ae0: 0x7ffff73311f0, needInterpret=<incomplete type>) at
src/dmd/initsem.d:962
#9  0x0000555555b156a7 in Semantic2Visitor::visit(VarDeclaration*)
(this=0x7fffffffd350, vd=0x7ffff7b06a90) at src/dmd/semantic2.d:276
#10 0x00005555559e0f5a in VarDeclaration::accept(Visitor*)
(this=0x7ffff7b06a90, v=0x7fffffffd350) at src/dmd/declaration.d:1724
#11 0x0000555555b14daa in semantic2(Dsymbol*, Scope*) (dsym=0x7ffff7b06a90,
sc=0x7ffff73312f0) at src/dmd/semantic2.d:79
#12 0x0000555555b15a67 in Semantic2Visitor::visit(Module*)
(this=0x7fffffffd410, mod=0x7ffff7b057a0) at src/dmd/semantic2.d:356
#13 0x0000555555a03bca in Module::accept(Visitor*) (this=0x7ffff7b057a0,
v=0x7fffffffd410) at src/dmd/dmodule.d:1261
#14 0x0000555555b14daa in semantic2(Dsymbol*, Scope*) (dsym=0x7ffff7b057a0,
sc=0x0) at src/dmd/semantic2.d:79
#15 0x000055555598bf7d in _D3dmd4mars7tryMainFmPPxaKSQz7globals5ParamZi
(params=..., argv=0x7fffffffdc98, argc=2) at src/dmd/mars.d:462
#16 0x000055555598dc7d in _Dmain (_param_0=...) at src/dmd/mars.d:962
```

Build from master as of today (2.102), has been crashing since 2.098 (error
before). The underlying problem seems to be the way CTFE handles `CommaExp`
rewrites.

--