zlib, harsh compiler warnings and configure test

Question

I'm trying to compile zlib from the command line, and I'm getting this message when using -Wall -Wextra -Wconversion (full cross-compile script is below):

Compiler error reporting is too harsh for ./configure (perhaps remove -Werror).

Here's the configure test that's generating the line:

cat > $test.c << EOF
int foo() { return 0; }
EOF
echo "Checking for obsessive-compulsive compiler options..." >> configure.log
if try $CC -c $CFLAGS $test.c; then
  :
else
  echo "Compiler error reporting is too harsh for $0 (perhaps remove -Werror)." | tee -a configure.log
  leave 1
fi

Its not clear to me what exactly is being judged too harsh (especially since -Werror is not present). I also don't quite understand what the sample program used in the test is doing, so its not clear to me what the criteria is for judging the compiler warnings "too harsh".

What is zlib complaining is too harsh?

---

#! /bin/sh

export PATH="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin:$PATH"

export CC=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
export CXX=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
export LD=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld
export AR=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar
export RANLIB=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib

export CFLAGS="-Wall -Wextra -Wconversion --sysroot="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdks""
export CXXFLAGS="-Wall -Wextra -Wconversion --sysroot="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk""

Answer 1

I had the exact same problem on a newly built machine, and I found the cause was that I didn't actually have the appropriate GNU C compilers installed (reference). Therefore it's complaining that the compiler is too harsh simply because there is no compiler.

Try running:

sudo apt-get install build-essential

and then try running your ./configure again.

Answer 2

My problem was:
cc1: error while loading shared libraries: libimf.so: cannot open shared object file: No such file or directory

Search for details in configure.log.