how to work around some compilation failures

C compilers are getting more aggressive with warnings and are producing
more false positives.  While I intend to keep ssocr compiling without
warnings (as in the last 15 years), I do not use the newest C compilers,
but rather the GCC version included in a stable GNU/Linux distribution,
it may take some time for me to encounter those problems myself, and thus
it may take some time for me to work around them.

A user reported a compilation failure due to new warnings in GCC 10.1.
Since I currently use GCC 7.5.0 from Ubuntu 18.04 LTS, I do not see
those warnings yet, and thus cannot test any workarounds yet.

A first investigation into the issue hints at a need to replace valid code
with code invalid for GCC's default C standard version (necessitating
the specification of a newer C standard in the CFLAGS) to work around
said problem.  I have no idea if there are additional warnings with GCC
10.1 after working around that one.  Since Google blocks my emails to
the reporting user, I cannot even communicate to find this out.  Thus any
code changes will have to wait for either a GCC version with additional
warnings arriving in my GNU/Linux distribution, or establishment of a
different communication channel, e.g., a GitHub issue.

INSTALL

@@ -54,6 +54,8 @@ Platform Specifics
 - On macOS, you may need to specify the X11 include path manually, using e.g.
   make CPPFLAGS=-I/opt/X11/include
 
+C Compiler Problems:
+--------------------
 Some users have reported problems with their C compilers.  If you are not
 using a stable release version of GCC, you may need to disable security
 features supposed to be provided by the C compiler, but broken in your
@@ -65,6 +67,23 @@ CFLAGS definition in the Makefile:
 If you need to do this to compile ssocr, please consider reporting the issue
 to your source for your C compiler (e.g., vendor or distribution).
 
+Another problem can be the introduction of new compiler warnings.  Some of
+those are prone to false positives, and this problem does occur for stable
+GCC releases as well.  Because ssocr's CFLAGS include both options -Werror
+and -pedantic-errors, false positives will break compilation of ssocr.
+To work around this problem, you can remove both of these options from
+the CFLAGS definition in the Makefile:
+
+    -Werror -pedantic-errors
+
+If you suspect that your C compiler has problems with the ssocr source code,
+you can use the minimal CFLAGS definition given below:
+
+    CFLAGS := $(shell imlib2-config --cflags)
+
+You can do this by commenting out the default CFLAGS definition and removing
+the comment sign in front of the minimal CFLAGS definition in the Makefile.
+
 Website
 -------
 You can get the current ssocr version from the official ssocr website:

Makefile

@@ -1,3 +1,6 @@
+# minimal CFLAGS definition (try if compilation fails with default CFLAGS)
+#CFLAGS  := $(shell imlib2-config --cflags)
+# default CFLAGS definition
 CFLAGS  := -D_FORTIFY_SOURCE=2 -Wall -W -Wextra -pedantic -Werror -pedantic-errors -fstack-protector-all $(shell imlib2-config --cflags) -O3
 LDLIBS  := -lm $(shell imlib2-config --libs)
 PREFIX  := /usr/local