From 2b8f6ba5371b23960ac80b8cd90a77434ceaab40 Mon Sep 17 00:00:00 2001
From: Olivia Appleton <olivia.kay.appleton@gmail.com>
Date: Sat, 28 Sep 2024 22:07:11 -0500
Subject: [PATCH] Add constant for max supported int

---
 docs/src/fortran/lib/constants.rst |  2 ++
 fortran/src/include/constants.f90  | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/docs/src/fortran/lib/constants.rst b/docs/src/fortran/lib/constants.rst
index 67c3ebf2..d1b8f9fc 100644
--- a/docs/src/fortran/lib/constants.rst
+++ b/docs/src/fortran/lib/constants.rst
@@ -11,6 +11,8 @@ View source code :source:`fortran/include/constants.f90`
     :type: integer
 .. f:variable:: i18t
     :type: integer
+.. f:variable:: imaxt
+    :type: integer
 
     A set of digit type constraints that denote how many decimal digits a number can support.
     They are given as ``i<len>t`` or ``r<len>_<exp>t``
diff --git a/fortran/src/include/constants.f90 b/fortran/src/include/constants.f90
index 329b2793..05617081 100644
--- a/fortran/src/include/constants.f90
+++ b/fortran/src/include/constants.f90
@@ -4,6 +4,16 @@ module constants
     integer, parameter :: i1t = selected_int_kind(1)
     integer, parameter :: i4t = selected_int_kind(4)
     integer, parameter :: i18t = selected_int_kind(18)
+    integer :: imaxt
+    if (selected_int_kind(38) >= 0) then
+        imaxt = selected_int_kind(38)
+    elseif (i18t >= 0) then
+        imaxt = i18t
+    else
+        ! fall back to default value of 64-bit in most compilers
+        imaxt = 8
+        i18t = 8
+    end if
 
     integer(i1t), parameter :: errort = 0
     integer(i1t), parameter :: int64t = 1