From e16d501129c701127efdd20da8d80c6ecdd081d4 Mon Sep 17 00:00:00 2001
From: Devin Kees <6895754+djkees@users.noreply.github.com>
Date: Wed, 2 Sep 2026 10:39:08 -0600
Subject: [PATCH] Define _WIN32 for gfortran when building vendored GFE/pFUnit
 on Windows (#167)

gfortran's -cpp preprocessing doesn't predefine _WIN32 the way a C/C++
compiler does, so FUnit.F90's #ifndef _WIN32 guard around
`use pf_RegexFilter` picks the wrong branch on Windows even though
CMake's own WIN32 check already excluded that module from the build.
See djkees/cea#163.

(cherry picked from commit 2fff96d7dfd91a9c554616d0c4c5abcd55343a6d)
---
 scripts/develop.sh | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/scripts/develop.sh b/scripts/develop.sh
index 6c7cf8b..9ee8fa0 100755
--- a/scripts/develop.sh
+++ b/scripts/develop.sh
@@ -108,16 +108,30 @@ if [ "$BUILD_GFE" = true ]; then
         git clone https://github.com/Goddard-Fortran-Ecosystem/GFE "${GFE}"
         (cd "${GFE}" && git submodule update --init)
     fi
-    cmake -S "${GFE}" -B "${GFE_BUILD}" -G "${GENERATOR}" \
-        -DCMAKE_CXX_COMPILER="${CXX}" \
-        -DCMAKE_Fortran_COMPILER="${FC}" \
-        -DCMAKE_INSTALL_PREFIX="${INSTALL}" \
-        -DCMAKE_BUILD_TYPE=Release \
-        -DSKIP_MPI=YES \
-        -DSKIP_OPENMP=YES \
-        -DSKIP_FHAMCREST=YES \
-        -DSKIP_ESMF=YES \
+    GFE_CMAKE_ARGS=(
+        -DCMAKE_CXX_COMPILER="${CXX}"
+        -DCMAKE_Fortran_COMPILER="${FC}"
+        -DCMAKE_INSTALL_PREFIX="${INSTALL}"
+        -DCMAKE_BUILD_TYPE=Release
+        -DSKIP_MPI=YES
+        -DSKIP_OPENMP=YES
+        -DSKIP_FHAMCREST=YES
+        -DSKIP_ESMF=YES
         -DSKIP_ROBUST=YES
+    )
+    case "$(uname -s)" in
+        MINGW*|MSYS*|CYGWIN*)
+            # gfortran's -cpp preprocessor does not predefine _WIN32 the way a
+            # C/C++ compiler does, but pFUnit's FUnit.F90 guards its
+            # `use pf_RegexFilter` on `#ifndef _WIN32` while pFUnit's own
+            # CMakeLists excludes RegexFilter.F90 from the build via CMake's
+            # own (always-correct) WIN32 variable. Without this define,
+            # FUnit.F90 fails to compile: it tries to use a module that was
+            # never built.
+            GFE_CMAKE_ARGS+=(-DCMAKE_Fortran_FLAGS=-D_WIN32)
+            ;;
+    esac
+    cmake -S "${GFE}" -B "${GFE_BUILD}" -G "${GENERATOR}" "${GFE_CMAKE_ARGS[@]}"
     cmake --build ${GFE_BUILD} --target install -j ${JOBS}
 fi