error_stop: remove incorrect/obsolete code

I originally authored this routine, which is updated
for supported compilers. The logic selecting it in CMake was no
longer relevant.

Author: scivision

CMakeLists.txt

@@ -46,7 +46,7 @@ include(CheckFortranSourceCompiles)
 include(CheckFortranSourceRuns)
 check_fortran_source_runs("i=0; error stop i; end" f18errorstop)
 check_fortran_source_compiles("real, allocatable :: array(:, :, :, :, :, :, :, :, :, :); end" f03rank SRC_EXT f90)
-check_fortran_source_runs("use, intrinsic :: iso_fortran_env, only : real128; real(real128) :: x; x = x+1; end" f03real128)
+# check_fortran_source_runs("use, intrinsic :: iso_fortran_env, only : real128; real(real128) :: x; x = x+1; end" f03real128)
 
 if(NOT DEFINED CMAKE_MAXIMUM_RANK)
   set(CMAKE_MAXIMUM_RANK 4 CACHE STRING "Maximum array rank for generated procedures")

src/CMakeLists.txt

@@ -14,7 +14,7 @@ set(fppFiles
     stdlib_sorting.fypp
     stdlib_sorting_ord_sort.fypp
     stdlib_sorting_sort.fypp
-    stdlib_sorting_sort_index.fypp 
+    stdlib_sorting_sort_index.fypp
     stdlib_stats.fypp
     stdlib_stats_corr.fypp
     stdlib_stats_cov.fypp
@@ -69,12 +69,6 @@ target_include_directories(${PROJECT_NAME} PUBLIC
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_MODULEDIR}>
 )
 
-if(f18errorstop)
-  target_sources(${PROJECT_NAME} PRIVATE f18estop.f90)
-else()
-  target_sources(${PROJECT_NAME} PRIVATE f08estop.f90)
-endif()
-
 add_subdirectory(tests)
 
 install(TARGETS ${PROJECT_NAME}

src/Makefile.manual

@@ -31,8 +31,7 @@ SRCFYPP =\
         stdlib_stats_distribution_PRNG.fypp \
         stdlib_string_type.fypp
 
-SRC = f18estop.f90 \
-      stdlib_error.f90 \
+SRC = stdlib_error.f90 \
       stdlib_specialfunctions.f90 \
       stdlib_specialfunctions_legendre.f90 \
       stdlib_io.f90 \
@@ -67,7 +66,6 @@ $(SRCGEN): %.f90: %.fypp common.fypp
 	fypp $(FYPPFLAGS) $< $@
 
 # Fortran module dependencies
-f18estop.o: stdlib_error.o
 stdlib_ascii.o: stdlib_kinds.o
 stdlib_bitsets.o: stdlib_kinds.o
 stdlib_bitsets_64.o: stdlib_bitsets.o

src/f08estop.f90

@@ -6,21 +6,44 @@ module stdlib_error
 implicit none
 private
 
-interface ! f{08,18}estop.f90
-    module subroutine error_stop(msg, code)
-        !! version: experimental
-        !!
-        !! Provides a call to `error stop` and allows the user to specify a code and message
-        !! ([Specification](..//page/specs/stdlib_error.html#description_1))
-        character(*), intent(in) :: msg
-        integer, intent(in), optional :: code
-    end subroutine error_stop
-end interface
-
 public :: check, error_stop
 
 contains
 
+
+subroutine error_stop(msg, code)
+    !! version: experimental
+    !!
+    !! Provides a call to `error stop` and allows the user to specify a code and message
+    !! ([Specification](..//page/specs/stdlib_error.html#description_1))
+    !!
+    !! Aborts the program with nonzero exit code.
+    !! The "stop <character>" statement generally has return code 0.
+    !! To allow non-zero return code termination with character message,
+    !! error_stop() uses the statement "error stop", which by default
+    !! has exit code 1 and prints the message to stderr.
+    !! An optional integer return code "code" may be specified.
+    !!
+    !!##### Examples
+    !!
+    !!```fortran
+    !!  call error_stop("Invalid argument")
+    !!```
+    !!```fortran
+    !!  call error_stop("Invalid argument", 123)
+    !!```
+
+    character(*), intent(in) :: msg
+    integer, intent(in), optional :: code
+
+    if(.not.present(code)) error stop msg
+
+    write(stderr, '(a)') msg
+    error stop code
+
+end subroutine error_stop
+
+
 subroutine check(condition, msg, code, warn)
     !! version: experimental
     !!