Index: flang/test/Semantics/collectives03.f90
===================================================================
--- /dev/null
+++ flang/test/Semantics/collectives03.f90
@@ -0,0 +1,45 @@
+! RUN: %S/test_errors.sh %s %t %flang_fc1
+! REQUIRES: shell
+! Check for semantic errors in co_max() function calls
+
+module test_co_max
+  implicit none
+
+contains
+
+  subroutine test
+  
+    integer i, status
+    real vector(1)
+    real array(1,1,1, 1,1,1, 1,1,1, 1,1,1, 1,1,1)
+    character(len=1) string, message
+  
+    ! correct calls, should produce no errors
+    call co_max(i)
+    call co_max(i,   1)
+    call co_max(i,   1,              status)
+    call co_max(i,   1,              stat=status)
+    call co_max(i,   1,                           errmsg=message)
+    call co_max(i,   1,              stat=status, errmsg=message)
+    call co_max(i,   result_image=1, stat=status, errmsg=message)
+    call co_max(a=i, result_image=1, stat=status, errmsg=message)
+
+    call co_max(array,  result_image=1, stat=status, errmsg=message)
+    call co_max(vector, result_image=1, stat=status, errmsg=message)
+    call co_max(string, result_image=1, stat=status, errmsg=message)
+  
+    ! the error is seen as an incorrect type for the stat= argument
+    !ERROR: Actual argument for ‘stat=’ has bad type ‘CHARACTER(KIND=1,LEN=1_8)’
+    call co_max(i, 1, message)
+
+    ! the error is seen as too many arguments to the co_max() call
+    !ERROR: too many actual arguments for collective subroutines 'co_max'
+    call co_max(i,   result_image=1, stat=status, errmsg=message, 3.4)
+  
+    ! keyword argument with incorrect type
+    !ERROR: unknown keyword argument to intrinsic 'co_max'
+    call co_max(fake=3.4)
+  
+  end subroutine
+
+end module test_co_max