[Bug]: Calling an `extern proc` with an invalid number of arguments results in an internal error

[jabraham17]

Summary of Problem

Description: Incorrectly specifying and calling an extern function results in an internal error with the LLVM backend. If CHPL_DEVELOPER is set or --verify is used, the internal error is replaced by a LLVM verification error.

Using the C backend gets a nicer error during codegen: too few arguments to function call, single argument 'x' was not specified. However since this error comes from the C backend compiler, there error is about foo.c instead of foo.chpl.

Steps to Reproduce

Source Code:

foo.chpl

require "lib.h";
extern proc func();
func();

lib.h

void func(int x);

lib.c

void func(int x) { }

Compile command: chpl foo.chpl lib.c

Configuration Information

• Output of chpl --version: 2.2 prerelease
• Output of $CHPL_HOME/util/printchplenv --anonymize:

  CHPL_TARGET_PLATFORM: darwin
  CHPL_TARGET_COMPILER: llvm
  CHPL_TARGET_ARCH: arm64
  CHPL_TARGET_CPU: native *
  CHPL_LOCALE_MODEL: flat
  CHPL_COMM: none
  CHPL_TASKS: qthreads
  CHPL_LAUNCHER: none
  CHPL_TIMERS: generic
  CHPL_UNWIND: none
  CHPL_MEM: jemalloc
  CHPL_ATOMICS: cstdlib
  CHPL_GMP: system *
  CHPL_HWLOC: system *
  CHPL_RE2: bundled *
  CHPL_LLVM: system
  CHPL_AUX_FILESYS: none

• Back-end compiler and version, e.g. gcc --version or clang --version: LLVM 18

[bradcray]

It would be difficult to improve the situation for the C back-end without having our compiler parse .h files and validate that extern declarations match the C declarations.

The LLVM back-end effectively does this, (which is presumably what results in the internal error in developer/verify mode?), so seems more directly addressable.