Hello. I am trying to configure gcc with: ./configure --prefix=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/GCC-4.94/ --with-gmp=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Gmp-4.3.2/ --with-mpfr=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Mpfr-2.4.2/ --with-mpc=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Mpc-0.8.1/ --with-cloog=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Cloog-0.18.1/ --with-isl=/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Isl-0.12.2/ and all I receive it is: checking for version 0.10 of ISL... no checking for version 0.11 of ISL... no checking for version 0.12 of ISL... no checking for version 0.14 of ISL... no checking for version 0.15 of ISL... no configure: error: Unable to find a usable ISL. See config.log for details. Then I proceeded to look in config.log. There I saw things like: configure:5894: checking for version 0.10 of ISL configure:5913: gcc -o conftest -g -O2 -I/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Isl-0.12.2//include -I/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Gmp-4.3.2//include -I/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Mpfr-2.4.2//include -I/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Mpc-0.8.1//include -L/media/34GB/Arquivos-de-Programas-Linux/Gcc-4.9.4/Isl-0.12.2//lib conftest.c -lisl >&5 configure:5913: $? = 0 configure:5913: ./conftest ./conftest: error while loading shared libraries: libisl.so.10: cannot open shared object file: No such file or directory configure:5913: $? = 127 configure: program exited with status 127 configure: failed program was: | /* confdefs.h */ | #define PACKAGE_NAME "" | #define PACKAGE_TARNAME "" | #define PACKAGE_VERSION "" | #define PACKAGE_STRING "" | #define PACKAGE_BUGREPORT "" | #define PACKAGE_URL "" | #define LT_OBJDIR ".libs/" | /* end confdefs.h. */ | #include <isl/version.h> | #include <string.h> | int | main () | { | if (strncmp (isl_version (), "isl-0.10", strlen ("isl-0.10")) != 0) | return 1; | | ; | return 0; | } configure:5922: result: no similar stuff happened with the test to versions 0.11-0.15 of ISL. I also tried with Isl 0.14 instead of 0.12.2 and the results were similar. So what's going on here?