Delayed import with forward declared procedure does not create valid C

[beef331]

Description

# Module main
proc doThing*()
import sub
proc doThing*() = echo "hmm"

# module sub.nim
import main
doThing()

Nim Version

2.0.8 and devel

Current Output

error: implicit declaration of function ‘doThing__a_u1’ [-Wimplicit-function-declaration]
   74 |         nimlf_(2, "/tmp/b.nim");        doThing__a_u1();

Expected Output

No response

Possible Solution

No response

Additional Information

No response

[exelotl]

As a word of warning for anyone who encounters this bug:

Passing -Wno-implicit-function-declaration to make the error go away is not a valid solution. Your program will compile but may behave slightly wrong, because the C compiler can make incorrect assumptions about what the function signature is.

e.g. I had an instance where GCC assumed my function returned int when it actually returned bool which lead to slightly wrong asm being produced.