Add disable-default-paths flags.

This makes it possible to disable hmatrix's usage of
hardcoded default paths like /usr/..., which is important
for hermetic builds such as on nix.

1 files changed, 14 insertions, 7 deletions

diff --git a/packages/gsl/hmatrix-gsl.cabal b/packages/gsl/hmatrix-gsl.cabal
index c81f241..d463ee8 100644
--- a/packages/gsl/hmatrix-gsl.cabal
+++ b/packages/gsl/hmatrix-gsl.cabal
@@ -23,6 +23,11 @@ flag onlygsl
     description:    don't link gslcblas
     default:        False
 
+flag disable-default-paths
+    description:    When enabled, don't add default hardcoded include/link dirs by default. Needed for hermetic builds like in nix.
+    default:        False
+    manual: True
+
 library
 
     Build-Depends:      base<5, hmatrix>=0.18, array, vector,
@@ -65,19 +70,21 @@ library
                         -fno-warn-unused-binds
 
     if os(OSX)
-        extra-lib-dirs: /opt/local/lib/
-        include-dirs: /opt/local/include/
-        extra-lib-dirs: /usr/local/lib/
-        include-dirs: /usr/local/include/
+        if !flag(disable-default-paths)
+            extra-lib-dirs: /opt/local/lib/
+            include-dirs: /opt/local/include/
+            extra-lib-dirs: /usr/local/lib/
+            include-dirs: /usr/local/include/
         extra-libraries: gsl
         if arch(i386)
             cc-options: -arch i386
         frameworks: Accelerate
 
     if os(freebsd)
-       extra-lib-dirs: /usr/local/lib
-       include-dirs: /usr/local/include
-       extra-libraries: gsl
+        if !flag(disable-default-paths)
+            extra-lib-dirs: /usr/local/lib
+            include-dirs: /usr/local/include
+        extra-libraries: gsl
 
     if os(windows)
         extra-libraries: gsl-0