title: error : command 'gcc' failed with exit status 1 while installing pygresql
body: <p>I am trying to install the pygresql package using "pip install pygresql" but I get the error : command 'gcc' failed with exit status 1
  I've tried a lot of thing but I still do not understand why it is not working</p>
  
  <pre><code>Collecting pygresql
    Using cached PyGreSQL-5.0.3.tar.gz
  Building wheels for collected packages: pygresql
    Running setup.py bdist_wheel for pygresql ... error
    Complete output from command /Users/paulinelanquetin/anaconda/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-build-s7kjrkvj/pygresql/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/tmpvvbd5puepip-wheel- --python-tag cp36:
    running bdist_wheel
    running build
    running build_py
    creating build
    creating build/lib.macosx-10.7-x86_64-3.6
    copying pg.py -&gt; build/lib.macosx-10.7-x86_64-3.6
    copying pgdb.py -&gt; build/lib.macosx-10.7-x86_64-3.6
    running build_ext
    building '_pg' extension
    creating build/temp.macosx-10.7-x86_64-3.6
    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/paulinelanquetin/anaconda/include -arch x86_64 -I/Users/paulinelanquetin/anaconda/include -arch x86_64 -DPYGRESQL_VERSION=5.0.3 -DDIRECT_ACCESS -DLARGE_OBJECTS -DDEFAULT_VARS -DESCAPING_FUNCS -I/Users/paulinelanquetin/anaconda/include/python3.6m -I/usr/local/Cellar/postgresql/9.6.2/include -I/Users/paulinelanquetin/anaconda/include/python3.6m -c pgmodule.c -o build/temp.macosx-10.7-x86_64-3.6/pgmodule.o -O2 -funsigned-char -Wall -Werror
    pgmodule.c:3694:3: error: code will never be executed [-Werror,-Wunreachable-code]
                    long    num_rows;
                    ^~~~~~~~~~~~~~~~~
    1 error generated.
    error: command 'gcc' failed with exit status 1
  
    ----------------------------------------
    Failed building wheel for pygresql
    Running setup.py clean for pygresql
  Failed to build pygresql
  Installing collected packages: pygresql
    Running setup.py install for pygresql ... error
      Complete output from command /Users/paulinelanquetin/anaconda/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-build-s7kjrkvj/pygresql/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-l99qu955-record/install-record.txt --single-version-externally-managed --compile:
      running install
      running build
      running build_py
      creating build
      creating build/lib.macosx-10.7-x86_64-3.6
      copying pg.py -&gt; build/lib.macosx-10.7-x86_64-3.6
      copying pgdb.py -&gt; build/lib.macosx-10.7-x86_64-3.6
      running build_ext
      building '_pg' extension
      creating build/temp.macosx-10.7-x86_64-3.6
      gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/Users/paulinelanquetin/anaconda/include -arch x86_64 -I/Users/paulinelanquetin/anaconda/include -arch x86_64 -DPYGRESQL_VERSION=5.0.3 -DDIRECT_ACCESS -DLARGE_OBJECTS -DDEFAULT_VARS -DESCAPING_FUNCS -I/Users/paulinelanquetin/anaconda/include/python3.6m -I/usr/local/Cellar/postgresql/9.6.2/include -I/Users/paulinelanquetin/anaconda/include/python3.6m -c pgmodule.c -o build/temp.macosx-10.7-x86_64-3.6/pgmodule.o -O2 -funsigned-char -Wall -Werror
      pgmodule.c:3694:3: error: code will never be executed [-Werror,-Wunreachable-code]
                      long    num_rows;
                      ^~~~~~~~~~~~~~~~~
      1 error generated.
      error: command 'gcc' failed with exit status 1
  
      ----------------------------------------
  Command "/Users/paulinelanquetin/anaconda/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-build-s7kjrkvj/pygresql/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-l99qu955-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/var/folders/y9/vbfql6394h3g6_4ldhwqzx1c0000gp/T/pip-build-s7kjrkvj/pygresql/
  </code></pre>