[flang] Add a semantics test for co_max

[rouson]

Summary

This patch checks for valid and invalid forms of calls to the collective subroutine co_max.

[rouson]

1. Add co_max test to expectedly failed list.
2. Replaced non-ASCII characters.
3. Correct expected error message.
4. Update run directive to use test_errors.py.

[ktras]

LGTM

[rouson]

As suggested in Diff D113086, the updated diff

1. Removes trailing whitespace if present.
2. Cites the section of the standard that defines the co_max interface.
3. Adds a check for an error in which the first co_max argument is coindexed.

The diff also adds checks for additional expected errors due to argument type mismatches.

[rouson]

1. Expand types tested for argument 'a'.
2. Vary the types tested more throughout the test.
3. Replace several "to be determined" error messages.
4. Fix typo: remove extraneous comma.
5. Clarify the "To Do" comment.

[ktras]

Latest diff improves the breadth of the test. LGTM.

flang/test/Semantics/collectives03.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! XFAIL: *
+! This test checks for semantic errors in co_max subroutine calls based on
+! the co_max interface defined in section 16.9.47 of the Fortran 2018 standard.
+! To Do: add co_max to the list of intrinsics
+
+program test_co_max
+  implicit none
+
+  integer          i, integer_array(1), coindexed_integer[*], status
+  character(len=1) c, character_array(1), coindexed_character[*], message
+  double precision d, double_precision_array(1)
+  real             r, real_array(1), coindexed_real[*]
+  complex          complex_type
+  logical          bool
+  
+  !___ standard-conforming calls with no keyword arguments ___
+  call co_max(i)
+  call co_max(c)
+  call co_max(d)
+  call co_max(r)
+  call co_max(i, 1)
+  call co_max(c, 1, status)
+  call co_max(d, 1, status, message)
+  call co_max(r, 1, status, message)
+  call co_max(integer_array)
+  call co_max(character_array, 1)
+  call co_max(double_precision_array, 1, status)
+  call co_max(real_array, 1, status, message)
+
+  !___ standard-conforming calls with keyword arguments ___
+
+  ! all arguments present
+  call co_max(a=i, result_image=1, stat=status, errmsg=message) 
+  call co_max(result_image=1, a=i, errmsg=message, stat=status) 
+
+  ! one optional argument not present
+  call co_max(a=i,                 stat=status, errmsg=message) 
+  call co_max(a=i, result_image=1,              errmsg=message)
+  call co_max(a=i, result_image=1, stat=status                )
+
+  ! two optional arguments not present
+  call co_max(a=i, result_image=1                             ) 
+  call co_max(a=i,                 stat=status                )
+  call co_max(a=i,                              errmsg=message) 
+
+  ! no optional arguments present
+  call co_max(a=i) 
+
+  !___ non-standard-conforming calls ___
+
+  ! argument 'a' shall be of numeric type
+  !ERROR: Actual argument for 'a=' has bad type 'LOGICAL(4)'
+  call co_max(bool)
+  
+  ! argument 'a' shall be of numeric type
+  !ERROR: Actual argument for 'a=' has bad type 'COMPLEX(4)'
+  call co_max(complex_type)
+  
+  ! argument 'a' is intent(inout)
+  !ERROR: Actual argument associated with INTENT(IN OUT) dummy argument 'a=' must be definable
+  call co_max(a=1+1)
+  
+  ! argument 'a' shall not be a coindexed object
+  !ERROR: to be determined
+  call co_max(a=coindexed_real[1])
+  
+  ! 'result_image' argument shall be a scalar
+  !ERROR: too many actual arguments for intrinsic 'co_max'
+  call co_max(i, result_image=bool)
+  
+  ! 'result_image' argument shall be an integer scalar
+  !ERROR: too many actual arguments for intrinsic 'co_max'
+  call co_max(c, result_image=integer_array)
+  
+  ! 'stat' argument shall be noncoindexed
+  !ERROR: to be determined
+  call co_max(d, stat=coindexed_integer[1])
+ 
+  ! 'stat' argument shall be an integer
+  !ERROR: Actual argument for 'stat=' has bad type 'CHARACTER(KIND=1,LEN=1_8)'
+  call co_max(r, stat=message)
+ 
+  ! 'stat' argument shall be an integer scalar
+  !ERROR: 'stat=' argument has unacceptable rank 1
+  call co_max(i, stat=integer_array)
+ 
+  ! 'errmsg' argument shall be noncoindexed
+  !ERROR: to be determined
+  call co_max(c, errmsg=coindexed_character[1])
+ 
+  ! 'errmsg' argument shall be character scalar
+  !ERROR: 'errmsg=' argument has unacceptable rank 1
+  call co_max(d, errmsg=character_array)
+ 
+  ! the error is seen as too many arguments to the co_max() call
+  !ERROR: too many actual arguments for intrinsic 'co_max'
+  call co_max(r, result_image=1, stat=status, errmsg=message, 3.4)
+  
+  ! keyword argument with incorrect name
+  !ERROR: unknown keyword argument to intrinsic 'co_max'
+  call co_max(fake=3.4)
+  
+end program test_co_max