Magic UDAs dont get recogize by uda.cpp

[zero-vector]

Code to reproduce

file: test1.d

extern(C) __gshared bool test = true; 
void main() {}

file: test2.d

module test2; 
import ldc.attributes : weak; 

extern(C) __gshared @weak bool test = false; 
pragma(msg,  __traits(getAttributes, test)); // this triggers the error

command:
ldc2 -c test2.d && ldc2 test1.d test2.o

result

AliasSeq!(_weak())
/usr/bin/ld: test2.o:(.bss.test+0x0): multiple definition of `test'; test1.o:(.data.test+0x0): first defined here
collect2: error: ld returned 1 exit status

Observation

ldc defines most udas in arguments.d like this:

immutable weak = _weak();
private struct _weak {}

ldc/runtime/druntime/src/ldc/attributes.d

Line 424 in 3883e04

immutable weak = _weak();

uda.cpp scans symbols for attributes by checking isStructLiteralExp()

ldc/gen/uda.cpp

Line 98 in 3883e04

if (auto sle = attr->isStructLiteralExp())

but if expressionSemantic was run prior to this check, the attr expression is VarExp and the check fails.

A simple __traits(getAttributes, sym) can trigger this error.

Changing immutable to enum fixes the issue, but there is probably a reason immutable was chosen.

[JohanEngelen]

Changing immutable to enum fixes the issue, but there is probably a reason immutable was chosen.

I don't remember there being a reason for immutable. If enum fixes the issue and does not trigger a new issue, then let's change it. (may be better than immutable too, because the enum will not need an address (no storage allocation needed))

[crazymonkyyy]

immutable polly = _polly();
 private struct _polly
 {
 }

this pattern is copied a few times from 9 years ago code but newer code uses something a bit strange but looks saner to my eyes; id probaly try converting all of this to struct weak{} for udas and if someone broke this years ago it probably should be tested if anything in this file works