Question: While making a project with Makefile, I get this error:

```
error: implicit declaration of function ‘fatal’ [-Werror=implicit-function-declaration]

cc1: all warnings being treated as errors

```

The `./configure --help` shows:

```
Optional Features:
  --disable-option-checking  ignore unrecognized --enable/--with options
  --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
  --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
  --disable-dependency-tracking  speeds up one-time build
  --enable-dependency-tracking   do not reject slow dependency extractors
  --disable-gtktest       do not try to compile and run a test GTK+ program
  --enable-debug    Turn on debugging

```

How can I tell *configure* not to include [-Werror](https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Werror)?

Answer: 
It seems like the feature has been in [autotools](https://en.wikipedia.org/wiki/GNU_Autotools) for many years:

```
./configure --disable-werror

```

Unfortunately, I wasn't able to get the following specific case to work:

```
./configure --enable-wno-error=unused-value

```

Maybe it could work if one escaped the '`=`' symbol, assuming it's possible. Like [skim says](https://stackoverflow.com/questions/8132594/disable-werror-in-configure-file/8282450#8282450), one can still use `CFLAGS` or `CXXFLAGS`.
I ran into this problem, and it turned out that GCC ***was not installed*** on my freshly-started [EC2](https://en.wikipedia.org/wiki/Amazon_Elastic_Compute_Cloud) instance running [Ubuntu 20.04](https://en.wikipedia.org/wiki/Ubuntu_version_history#Ubuntu_20.04_LTS_(Focal_Fossa)) (Focal Fossa).

Simply running `sudo apt install gcc` fixed this issue for me.