Make support for quadruple precision optional

- use checks in CMake to automatically determine whether quadruple precision is available
- default to values in kind we run from the manual makefile don't want to run checks
- skip all tests explicitly referencing the quadruple precision kind parameter
- add check for extended double precision (available with GCC)

Author: awvwgk

CMakeLists.txt

@@ -24,7 +24,6 @@ if(CMAKE_Fortran_COMPILER_ID STREQUAL GNU)
   add_compile_options(-Wall)
   add_compile_options(-Wextra)
   add_compile_options(-Wimplicit-procedure)
-  add_compile_options(-Wconversion-extra)
   # -pedantic-errors triggers a false positive for optional arguments of elemental functions,
   # see test_optval and https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95446
   if(CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 11.0)

config/CMakeLists.txt

@@ -13,6 +13,24 @@ endif()
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}" PARENT_SCOPE)
 
+# Check for available features
+# Note: users can overwrite the automatic check by setting the value at configure time
+include(CheckFortranSourceRuns)
+if (NOT DEFINED WITH_QP)
+  check_fortran_source_runs(
+    "if (selected_real_kind(33) == -1) stop 1; end"
+    WITH_QP
+  )
+endif()
+if (NOT DEFINED WITH_XDP)
+  set(WITH_QP ${WITH_QP} PARENT_SCOPE)
+  check_fortran_source_runs(
+    "if (any(selected_real_kind(18) == [-1, selected_real_kind(33)])) stop 1; end"
+    WITH_XDP
+  )
+  set(WITH_XDP ${WITH_XDP} PARENT_SCOPE)
+endif()
+
 # Export a pkg-config file
 configure_file(
   "${CMAKE_CURRENT_SOURCE_DIR}/template.pc"

config/template.cmake

@@ -1,5 +1,8 @@
 @PACKAGE_INIT@
 
+set("@PROJECT_NAME@_WITH_QP" @WITH_QP@)
+set("@PROJECT_NAME@_WITH_XDP" @WITH_XDP@)
+
 if(NOT TARGET "@PROJECT_NAME@::@PROJECT_NAME@")
   include("${CMAKE_CURRENT_LIST_DIR}/@[email protected]")
 endif()

doc/specs/stdlib_kinds.md

@@ -16,17 +16,24 @@ The `stdlib_kinds` module provides kind parameters for the Fortran intrinsic dat
 
 ### `sp`
 
-Alias for intrinsic named constant `real32` imported from `iso_fortran_env`.
+Provides real kind parameter for floating point numbers with a minimal precision of 6 significant digits.
 
 
 ### `dp`
 
-Alias for intrinsic named constant `real64` imported from `iso_fortran_env`.
+Provides real kind parameter for floating point numbers with a minimal precision of 15 significant digits.
+
+
+### `xdp`
+
+Provides real kind parameter for floating point numbers with a minimal precision of 18 significant digits.
+If not available it has value `-1`.
 
 
 ### `qp`
 
-Alias for intrinsic named constant `real128` imported from `iso_fortran_env`.
+Provides real kind parameter for floating point numbers with a minimal precision of 33 significant digits.
+If not available it has value `-1`.
 
 
 ### `int8`

src/CMakeLists.txt

@@ -50,6 +50,12 @@ else()
   set(fyppFlags "-DVERSION90")
 endif()
 
+list(
+  APPEND fyppFlags
+  "-DWITH_QP=$<BOOL:${WITH_QP}>"
+  "-DWITH_XDP=$<BOOL:${WITH_XDP}>"
+)
+
 fypp_f90("${fyppFlags}" "${fppFiles}" outFiles)
 
 set(SRC

src/common.fypp

@@ -1,7 +1,23 @@
 #:mute
 
+#! Support for quadruple precision floating point numbers
+#:if not defined("WITH_QP")
+#:set WITH_QP = 0
+#:endif
+
+#! Support for extended double precision floating point numbers
+#:if not defined("WITH_XDP")
+#:set WITH_XDP = 0
+#:endif
+
 #! Real kinds to be considered during templating
-#:set REAL_KINDS = ["sp", "dp", "qp"]
+#:set REAL_KINDS = ["sp", "dp"]
+#:if WITH_XDP
+#:set REAL_KINDS = REAL_KINDS + ["xdp"]
+#:endif
+#:if WITH_QP
+#:set REAL_KINDS = REAL_KINDS + ["qp"]
+#:endif
 
 #! Real types to be considered during templating
 #:set REAL_TYPES = ["real({})".format(k) for k in REAL_KINDS]
@@ -10,7 +26,13 @@
 #:set REAL_KINDS_TYPES = list(zip(REAL_KINDS, REAL_TYPES))
 
 #! Complex kinds to be considered during templating
-#:set CMPLX_KINDS = ["sp", "dp", "qp"]
+#:set CMPLX_KINDS = ["sp", "dp"]
+#:if WITH_XDP
+#:set CMPLX_KINDS = CMPLX_KINDS + ["xdp"]
+#:endif
+#:if WITH_QP
+#:set CMPLX_KINDS = CMPLX_KINDS + ["qp"]
+#:endif
 
 #! Complex types to be considered during templating
 #:set CMPLX_TYPES = ["complex({})".format(k) for k in CMPLX_KINDS]

src/stdlib_io.fypp

@@ -6,7 +6,7 @@ module stdlib_io
   !! Provides a support for file handling
   !! ([Specification](../page/specs/stdlib_io.html))
 
-  use stdlib_kinds, only: sp, dp, qp, &
+  use stdlib_kinds, only: sp, dp, xdp, qp, &
       int8, int16, int32, int64
   use stdlib_error, only: error_stop
   use stdlib_optval, only: optval
@@ -24,9 +24,11 @@ module stdlib_io
     FMT_INT = '(*(i0,1x))', &
     FMT_REAL_SP = '(*(es15.8e2,1x))', &
     FMT_REAL_DP = '(*(es24.16e3,1x))', &
+    FMT_REAL_XDP = '(*(es26.18e3,1x))', &
     FMT_REAL_QP = '(*(es44.35e4,1x))', &
     FMT_COMPLEX_SP = '(*(es15.8e2,1x,es15.8e2))', &
     FMT_COMPLEX_DP = '(*(es24.16e3,1x,es24.16e3))', &
+    FMT_COMPLEX_XDP = '(*(es26.18e3,1x,es26.18e3))', &
     FMT_COMPLEX_QP = '(*(es44.35e4,1x,es44.35e4))'
 
   interface loadtxt

src/stdlib_kinds.f90

@@ -1,14 +1,26 @@
+!> Version: experimental
+!>
+!> The specification of this module is available [here](../page/specs/stdlib_kinds.html).
 module stdlib_kinds
-!! version: experimental
-use iso_fortran_env, only: sp=>real32, dp=>real64, qp=>real128
-use iso_fortran_env, only: int8, int16, int32, int64
-use iso_c_binding, only: c_bool
-! If we decide later to use iso_c_binding instead of iso_fortran_env:
-!use iso_c_binding, only: sp=>c_float, dp=>c_double, qp=>c_float128
-!use iso_c_binding, only: int8=>c_int8_t, int16=>c_int16_t, int32=>c_int32_t, int64=>c_int64_t
-implicit none
-private
-public sp, dp, qp, int8, int16, int32, int64, lk, c_bool
-
-integer, parameter :: lk = kind(.true.)
+  use iso_fortran_env, only: int8, int16, int32, int64
+  use iso_c_binding, only: c_bool
+  implicit none
+  private
+  public :: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c_bool
+
+  !> Single precision real numbers
+  integer, parameter :: sp = selected_real_kind(6)
+
+  !> Double precision real numbers
+  integer, parameter :: dp = selected_real_kind(15)
+
+  !> Extended double precision real numbers
+  integer, parameter :: xdp = selected_real_kind(18)
+
+  !> Quadruple precision real numbers
+  integer, parameter :: qp = selected_real_kind(33)
+
+  !> Default logical kind parameter
+  integer, parameter :: lk = kind(.true.)
+
 end module stdlib_kinds

src/stdlib_linalg.fypp

@@ -3,7 +3,7 @@
 module stdlib_linalg
   !!Provides a support for various linear algebra procedures
   !! ([Specification](../page/specs/stdlib_linalg.html))
-  use stdlib_kinds, only: sp, dp, qp, &
+  use stdlib_kinds, only: sp, dp, xdp, qp, &
     int8, int16, int32, int64
   use stdlib_optval, only: optval
   implicit none

src/stdlib_math.fypp

@@ -3,7 +3,7 @@
 #:set RC_KINDS_TYPES = REAL_KINDS_TYPES + CMPLX_KINDS_TYPES
 
 module stdlib_math
-    use stdlib_kinds, only: int8, int16, int32, int64, sp, dp, qp
+    use stdlib_kinds, only: int8, int16, int32, int64, sp, dp, xdp, qp
     use stdlib_optval, only: optval
 
     implicit none