write semantics tests for CHANGE TEAM statement.

[hussainjk]

Summary

Added semantics tests for aspects of CHANGE TEAM statements which are not duplicates from FORM TEAM statements.

[ktras]

Thanks @hussainjk for these tests. Per my comment inline of change_team01c.f90, the branching that is specified by the standard was not tested. However, locally I began to work on adding the ability for flang to check whether branching occurs or not in a change-team-construct, and while doing so I began to add to my local copy of your test to check my implementation. As I know that your focus is no longer on testing, if you update this patch and remove lines 11-24 from that test, then I can approve this patch. I will then add to your tests checks for branching in the patch that I submit to add additional checks on change-team-construct in flang.

flang/test/Semantics/change_team01c.f90

11

Per the 2018 Fortran standard 11.2 "Branching can be caused by a GO TO statement, a computed GO TO statement, a CALL statement that has an alt-return-spec, or an input/output statement that has an END=, EOR=, or ERR= specifier." So these tests from lines 11-24 do not test the constraint C1110, which I believe you intended to test.

[hussainjk]

Addressing review comments.

[ktras]

Thank you for making the requested changes.
LGTM.

[hussainjk]

Modified some block labels to fix a new label name collision error.

flang/test/Semantics/change_team01.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Check for semantic errors in change team statements.
+! Only those semantics which differ from those of FORM TEAM statements are checked.
+
+subroutine test
+  use, intrinsic :: iso_fortran_env, only: team_type
+  type(team_type) :: team
+  integer, codimension[*] :: selector
+  integer, codimension[2,*] :: selector2d
+
+  ! Valid invocations which should produce no errors.
+  block
+  change team (team)
+  end team
+  construct: change team (team)
+  end team construct
+  change team (team, ca[*] => selector)
+  end team
+  change team (team, ca[2,*] => selector)
+  end team
+  change team (team, ca[*] => selector)
+  end team
+  change team (team, ca[*] => selector, ca2[2,*] => selector2d)
+  end team
+  end block
+
+  !A selector may appear only once in selector-list.
+  ! ERROR: Selector 'selector' was already used as a selector or coarray in this statement
+  change team (team, ca[*] => selector, ca2[*] => selector)
+  end team
+
+  ! Within a CHANGE TEAM construct, a CYCLE or EXIT statement is not allowed if it belongs to an outer construct.
+  block
+  outer: if (.true.) then
+    change team (team)
+      if (.true.) then
+        ! ERROR: EXIT must not leave a CHANGE TEAM statement
+        exit outer
+      end if
+    end team
+  end if outer
+  end block
+  block
+  outer: do
+    change team (team)
+      ! ERROR: CYCLE must not leave a CHANGE TEAM statement
+      cycle outer
+    end team
+  end do outer
+  end block
+
+  ! The construct name must not be the same as any other construct name in the scoping unit.
+  block
+  construct: block
+  end block construct
+  ! ERROR: 'construct' is already declared in this scoping unit
+  construct: change team (team)
+  end team construct
+  end block
+
+  ! When the CHANGE TEAM statement is executed, the selectors must all be established coarrays.
+  ! ERROR: Selector in coarray association must name a coarray
+  change team (team, ca[*] => not_selector)
+  end team
+
+  ! The coarray name in a coarray-association must not be the same as the name as the name of another coarray or of a selector in the CHANGE TEAM statement.
+  ! ERROR: 'selector' is not an object that can appear in an expression
+  change team (team, selector[*] => selector)
+  end team
+end subroutine

flang/test/Semantics/change_team01b.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Check for semantic errors in change team statements
+! This subtest contains syntactic tests that prevent the main tests from being emitted.
+
+subroutine test
+  use, intrinsic :: iso_fortran_env, only: team_type
+  type(team_type) :: team
+
+  ! If a construct name appears on the CHANGE TEAM statement of the construct, the same name must also appear on the END TEAM construct.
+  block
+  construct: change team (team)
+  ! ERROR: CHANGE TEAM construct name required but missing
+  end team
+  end block
+  ! If a construct name appears on an END TEAM statement, the same construct name must appear on the corresponding CHANGE TEAM statement.
+  block
+  change team (team)
+  ! ERROR: CHANGE TEAM construct name unexpected
+  end team construct
+  end block
+  block
+  construct1: change team (team)
+  ! ERROR: CHANGE TEAM construct name mismatch
+  end team construct2
+  end block
+end subroutine
+
+

flang/test/Semantics/change_team01c.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! XFAIL: *
+! Check for semantic errors in change team statements.
+! This subtest contains tests for unimplemented errors.
+
+subroutine test
+  use, intrinsic :: iso_fortran_env, only: team_type
+  type(team_type) :: team
+  integer, codimension[*] :: selector
+
+  ! Branching into or out of a CHANGE TEAM construct is not permitted.
+  ! ERROR: TBD
+  block
+  construct: change team (team)
+  if (.true.) then
+    exit construct
+  end if
+  end team construct
+  end block
+  ! ERROR: TBD
+  if (.true.) then
+    change team (team)
+    end team
+  end if
+
+  ! A branch to an END TEAM statement is permitted only from within the corresponding CHANGE TEAM construct.
+  change team (team)
+    if (.true.) then
+      end team
+    end if
+  end team
+
+  ! A RETURN statement may not appear in a CHANGE TEAM construct.
+  change team (team)
+    ! ERROR: TBD
+    return
+  end team
+
+  ! On each image, the team variable specified in the CHANGE TEAM statement cannot become undefined or redefined during execution of the construct.
+  ! ERROR: TBD
+  change team (team)
+    team = get_team(INITIAL_TEAM)
+  end team
+end subroutine
+
+