Refering to a parameter/local var in an initializer of a {.global.} var results in invalid C code

[recloser]

compiling

proc foo(arg: int) =
    var g {.global.} = arg + 1
    echo g

foo(123)

produces

Error: execution of an external compiler program 'gcc -c  -w  -I'~/.choosenim/toolchains/nim-#devel/lib' -o ~/.cache/nim/bug_d/bug.c.o ~/.cache/nim/bug_d/bug.c' failed with exit code: 1

~/.cache/nim/bug_d/bug.c: In function 'NimMainModule':
~/.cache/nim/bug_d/bug.c:168:41: error: 'arg' undeclared (first use in this function)
  TM_rmH9bpP9b3ZIjFP4QhigizlA_2 = addInt(arg, ((NI) 1));
                                         ^~~
~/.cache/nim/bug_d/bug.c:168:41: note: each undeclared identifier is reported only once for each function it appears in

[alaviss]

If I understand this correctly, you want g to be initialized on the first call only, so you'd have to do this:

proc foo(arg: int) =
    var g {.global.} = 0
    once:
        g = arg + 1
    echo g

This is because {.global.}s are initialized during program startup, which of course, arg wouldn't be available then since it only exists within the proc.

The compiler should raise a proper error for this case however.

[Araq]

Duplicate of #3505