Bug#1107055: fftw3 FTCBFS: gfortran dependency not satisfiable

[Helmut Grohne]

Source: fftw3
Version: 3.3.10-2
Tags: patch
User: debian-cross at lists.debian.org
Usertags: cross-satisfiability

fftw3 fails to cross build from source, because its gfortran dependency
is not cross-satisfiable. Generally bare toolchain names cannot be used
for cross compilation, because they do not indicate whether they're
meant for the build or host architecture. In this case,
gfortran-for-host is what is needed.

However, gfortran-for-host cannot provide the bare "gfortran" name.
"${DEB_HOST_GNU_TYPE}-gfortran" must be used instead. We looked for
alternatives and they all regressed some use case. That said using
triplet-prefixed tools is explicit and works reliably even when building
natively.

I'm attaching a patch for your convenience, but I think applying it
should be deferred to forky.

Helmut
-------------- next part --------------
diff --minimal -Nru fftw3-3.3.10/debian/changelog fftw3-3.3.10/debian/changelog
--- fftw3-3.3.10/debian/changelog	2024-10-26 13:58:51.000000000 +0200
+++ fftw3-3.3.10/debian/changelog	2024-10-31 16:25:56.000000000 +0100
@@ -1,3 +1,10 @@
+fftw3 (3.3.10-2.1) UNRELEASED; urgency=medium
+
+  * Non-maintainer upload.
+  * Fix FTCBFS: Use gfortran-for-host. (Closes: #-1)
+
+ -- Helmut Grohne <helmut at subdivi.de>  Thu, 31 Oct 2024 16:25:56 +0100
+
 fftw3 (3.3.10-2) unstable; urgency=medium
 
   * Team upload.
diff --minimal -Nru fftw3-3.3.10/debian/control fftw3-3.3.10/debian/control
--- fftw3-3.3.10/debian/control	2024-10-26 13:58:05.000000000 +0200
+++ fftw3-3.3.10/debian/control	2024-10-31 16:25:54.000000000 +0100
@@ -6,7 +6,7 @@
 Priority: optional
 Build-Depends: chrpath,
                debhelper-compat (= 13),
-               gfortran,
+               gfortran-for-host,
                mpi-default-dev,
                texinfo
 Build-Depends-Indep: ghostscript
diff --minimal -Nru fftw3-3.3.10/debian/rules fftw3-3.3.10/debian/rules
--- fftw3-3.3.10/debian/rules	2024-10-26 13:57:20.000000000 +0200
+++ fftw3-3.3.10/debian/rules	2024-10-31 16:25:56.000000000 +0100
@@ -3,6 +3,7 @@
 DPKG_EXPORT_BUILDFLAGS = 1
 include /usr/share/dpkg/architecture.mk
 include /usr/share/dpkg/buildflags.mk
+include /usr/share/dpkg/buildtools.mk
 
 export DEB_BUILD_MAINT_OPTIONS=hardening=+all
 
@@ -54,9 +55,9 @@
 endif
 
 ifneq (,$(findstring nog77,$(DEB_BUILD_OPTIONS)))
-	archconfflags := $(archconfflags) F77="gfortran"
+	archconfflags := $(archconfflags) F77="$(F77)"
 else
-	archconfflags := $(archconfflags) F77="gfortran -ff2c"
+	archconfflags := $(archconfflags) F77="$(F77) -ff2c"
 endif
 
 # common configure options