added a bit more explanation

sagemath · Feb 25, 2019 · 06798ca · 06798ca
1 parent 0ca3f56
commit 06798ca
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/src/bin/sage-env-config.in b/src/bin/sage-env-config.in
@@ -39,5 +39,12 @@ fi
 # This is usually blank if the system GMP is used, or $SAGE_LOCAL otherwise
 export SAGE_GMP_PREFIX="@SAGE_GMP_PREFIX@"
 if [ -n "$SAGE_GMP_PREFIX" ]; then
+    # Many packages that depend on GMP accept a --with-gmp=<prefix> flag to
+    # their ./configure scripts.  When using the system's GMP this is not
+    # generally necessary, but when using the GMP package installed in
+    # SAGE_LOCAL it is useful to pass it.  We define this variable to
+    # pass to these packages' ./configure scripts.  When using the system
+    # GMP its value is just blank (for many of these packages passing
+    # --with-gmp without an argument is actually a bug)
     export SAGE_CONFIGURE_GMP="--with-gmp=$SAGE_GMP_PREFIX"
 fi