Names of subroutines do not match between caller, callee, and declaration in same compilation unit

[jleidel]

Yep:

SUBROUTINE MYSUB(B,N)
CHARACTER_1 B(1)
CHARACTER_1 BLNK
SAVE BLNK
DATA BLNK /' '/

DO 10 I=1,N
B(I)=BLNK
10 CONTINUE
RETURN
END

program invokecharblank
character_1 STRING(10)
integer_4 N
external MYSUB

N = 10
call MYSUB(STRING,N)

do 20 I=1,10
print *, 'string = ', STRING(I), '.'
20 continue

end
Compile with -S -emit-llvm and then pass it to clang with the rt library linked.
It will fail saying that the called function does not exist.

[jleidel]

In examining the IR, Flang appears to mangle the caller beyond appending the underscore. The IR shows:

subroutine definition:
define void @mysub_([1 x i8]* noalias %b, i32* noalias %n)

call location:
call void @mysub_.1([1 x i8]* %0, i32* %n)

The symbol is declared at the bottom of the IR as follows:
declare void @mysub_.1([1 x i8], i32)

[jleidel]

The bug occurs when the subroutines are defined as "external"

[jleidel]

Issue migrated from llvm-flang/flang-old#8

[ppenzin]

How to compile this? I copy-pasted everything in a file and got a bunch or compile-time errors, regardless of file extension (fixed or free-form).

[ppenzin]

Got it reproduced, never mind.