[bug#67822] [PATCH v2] gnu: maths: petsc: Reduce closure size.

[Lars Bilke]

Reduces closure size by around 350 MB by removing refernces to build
dependencies (e.g. gcc).

The v2 patch does not delete petscvariables but only removes some store
references. This fixes downstream packages such as e.g. dealii-openmpi.

Change-Id: I2e6900747b2118546f0a39ceb109b3f2f90e6949
---
 gnu/packages/maths.scm | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/gnu/packages/maths.scm b/gnu/packages/maths.scm
index 0f4d29b40f..8e8e380336 100644
--- a/gnu/packages/maths.scm
+++ b/gnu/packages/maths.scm
@@ -3484,8 +3484,20 @@ (define-public petsc
                           '("configure.log" "make.log" "gmake.log"
                             "test.log" "error.log" "RDict.db"
                             "PETScBuildInternal.cmake"
+                            "configure-hash"
                             ;; Once installed, should uninstall with Guix
                             "uninstall.py")))))
+          (add-after 'clean-install 'clear-reference-to-compiler
+            (lambda* (#:key inputs outputs #:allow-other-keys)
+              ;; Do not retain a reference to GCC and other build only inputs.
+              (let ((out (assoc-ref outputs "out")))
+              (substitute* (string-append out "/lib/petsc/conf/petscvariables")
+                (("/gnu/store/.*/bin/gcc") "gcc")
+                (("/gnu/store/.*/bin/g++") "g++")
+                (("/gnu/store/.*/bin/make") "make")
+                (("/gnu/store/.*/bin/diff") "diff")
+                (("/gnu/store/.*/bin/sed") "sed")
+                ))))
           (add-after 'install 'move-examples
             (lambda* (#:key outputs #:allow-other-keys)
               (let* ((out (assoc-ref outputs "out"))

base-commit: ac61e9705fb8c450c6cd0c1731fbb1b909c1f944
-- 
2.43.0