From 502a0d52dbc9eb16a6b07f359c9bebc347448c16 Mon Sep 17 00:00:00 2001
From: Sebastian Ehlert <28669218+awvwgk@users.noreply.github.com>
Date: Sat, 20 Aug 2022 11:38:18 +0200
Subject: [PATCH] Only preprocess current files

---
 fypp-gfortran.py    | 55 +++++++++++++++------------------------------
 src/fpm_sources.f90 |  4 ++--
 2 files changed, 20 insertions(+), 39 deletions(-)

diff --git a/fypp-gfortran.py b/fypp-gfortran.py
index f44625ff8d..08dee63f80 100755
--- a/fypp-gfortran.py
+++ b/fypp-gfortran.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python3
 import sys
 import subprocess
 from pathlib import Path
@@ -13,7 +14,16 @@
     output_dir.mkdir(parents=True)
 
 # Get the filenames with .fypp extension and convert to string.
-filenames = [str(f) for f in Path(".").glob("**/*.fypp")]
+source_file = [arg for arg in args if arg.endswith(".fypp")]
+output_file = [arg for arg in args if arg.endswith(".o")]
+
+if len(source_file) != len(output_file):
+    subprocess.run(["gfortran"] + args, check=True)
+    sys.exit(0)
+
+source_file = source_file[0]
+output_file = output_file[0]
+preprocessed = output_file.replace(".o", ".f90")
 
 # Filter out the macro definitions.
 macros = [arg for arg in args if arg.startswith("-D")]
@@ -21,39 +31,10 @@
 # Filter out the include paths with -I prefix.
 include_paths = [arg for arg in args if arg.startswith("-I")]
 
-# Declare preprocessed array.
-preprocessed = []
-
-# Preprocess the .fypp files.
-for filename in filenames:
-
-    # Get the output filename only without extension and path.
-    output_filename = Path(filename).stem
-
-    # Save the output_file to build directory.
-    output_file = str(Path(output_dir, f"{output_filename}.f90"))
-
-    subprocess.run(
-        [
-            "fypp",
-            filename,
-            *include_paths,
-            *macros,
-            output_file,
-        ],
-    )
-
-    # Append the output_file to preprocessed array.
-    # Along with the path to store object files.
-    # This will save the object files in preprocessed_files directory.
-    preprocessed.append(f"-c {output_file} -o {str(Path(output_dir, f'{output_filename}.o'))}")
-
-# Run gfortran for each preprocessed file.
-for file in preprocessed :
-    file_args = file.split()
-    subprocess.run(
-        ["gfortran"]  + file_args,
-        check=True,
-    )
-
-subprocess.run(["gfortran"] + args)
+subprocess.run(
+    ["fypp", "-n", source_file, preprocessed] + macros + include_paths,
+    check=True
+)
+
+args = [arg for arg in args if arg != source_file and not arg in macros] + [preprocessed]
+subprocess.run(["gfortran"] + args, check=True)
diff --git a/src/fpm_sources.f90 b/src/fpm_sources.f90
index b821362c55..16586da9ef 100644
--- a/src/fpm_sources.f90
+++ b/src/fpm_sources.f90
@@ -15,8 +15,8 @@ module fpm_sources
 private
 public :: add_sources_from_dir, add_executable_sources
 
-character(4), parameter :: fortran_suffixes(2) = [".f90", &
-                                                  ".f  "]
+character(5), parameter :: fortran_suffixes(3) = [".f90 ", ".fypp", &
+                                                  ".f   "]
 character(4), parameter :: c_suffixes(4) = [".c  ", ".h  ", ".cpp", ".hpp"]
 
 contains