From 54a34e1d781e62daafe9a7214bedf99313670f3a Mon Sep 17 00:00:00 2001
From: Lukas Schneiderbauer <lukas.schneiderbauer@gmail.com>
Date: Sat, 28 Dec 2024 13:51:20 +0100
Subject: [PATCH] update SystemRequirements again

---
 DESCRIPTION      | 4 +---
 configure        | 2 +-
 configure.ac     | 2 +-
 cran-comments.md | 4 ++--
 4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 075438b..ca73a47 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -32,9 +32,7 @@ Suggests:
 LinkingTo: 
     cpp11
 SystemRequirements:
-    fftw (>= 3.3.0),
-    fftwf (>= 3.3.0),
-    fftw3f_omp
+    fftw3 (including single precision support fftw3f), fftw3f_omp (optional), OpenMP (optional)
 Config/testthat/edition: 3
 URL: https://lschneiderbauer.github.io/fCWTr/, https://github.com/lschneiderbauer/fCWTr
 Roxygen: list(markdown = TRUE)
diff --git a/configure b/configure
index 0838a1e..50f8738 100755
--- a/configure
+++ b/configure
@@ -4274,7 +4274,7 @@ then :
   test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
   have_fftw=yes
 else case e in #(
-  e) as_fn_error $? "The fftw3f library is required." "$LINENO" 5
+  e) as_fn_error $? "The fftw3f library is required. In case fftw is already installed, you might need to enable fftw's single precision support with './configure --enable-float'." "$LINENO" 5
  ;;
 esac
 fi
diff --git a/configure.ac b/configure.ac
index cff45a9..96ce73d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,7 +41,7 @@ AC_SEARCH_LIBS(
   fftwf_free,
   fftw3f,
   [have_fftw=yes],
-  [AC_MSG_ERROR([The fftw3f library is required.])]
+  [AC_MSG_ERROR([The fftw3f library is required. In case fftw is already installed, you might need to enable fftw's single precision support with './configure --enable-float'.])]
 )
 
 # Check for omp.h header
diff --git a/cran-comments.md b/cran-comments.md
index 602ca4d..975f1bd 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -2,8 +2,8 @@
 
 This is a resubmission (after package being archived). In this version I have:
 
--   Changed 'SystemRequirements' to directly refer to single precission 'fftwf' and changed 'openmp' to 'fftwf_omp'.
--   I do not understand the comment 'does not test for [fftwf]': ./configure.ac, line #40, contains a paragraph that tests for single precision functions. The configuration fails with a descriptive error message "The fftw3f library is required." in case it does not find a fitting library. I searched the "Writing R Extensions" documentation for additional mandatory places, where a check should occur, to no avail.
+-   Changed 'SystemRequirements' to directly refer to single precision 'fftw3f' and added 'fftw3f_omp'. I also indicated the OpenMP requirement as optional. I removed version requirements (since '3' implies version 3).
+-   The comment "[The package] does not test for [fftwf]" seems incorrect to me: The file ./configure.ac, line #40, contains a paragraph that tests for single precision functions. The configuration fails with a descriptive error message "The fftw3f library is required." in case it does not find a fitting library. I now added additional information to this error message to make it more clear what is missing. I searched the "Writing R Extensions" documentation for additional mandatory places, where a check should occur, to no avail.
 -   I also added other features, unrelated to the comments, since last submission/archiving.
 
 ## R CMD check results