add section on compilation warnings

1 files changed, 27 insertions, 6 deletions

diff --git a/INSTALL b/INSTALL
index f473eba..292bfe4 100644
--- a/INSTALL
+++ b/INSTALL
@@ -9,7 +9,7 @@ need to configure, build, test, and install rc.
     # make install
 
 This will build rc in the source directory (see below for details on how
-to build rc in a different directory).  
+to build rc in a different directory).
 
 BUILD AND CONFIGURATION OPTIONS
 
@@ -21,7 +21,9 @@ libraries.  For a summary of all options, run `sh configure --help'.
 You can specify Makefile variables by setting the corresponding
 environment variables.  For example, you might want to set `CC=cc', to
 prevent configure looking for gcc, or set an initial value for `LIBS',
-as in the example below.
+as in the example below.  It is a good idea to specify static linking
+(unless you are linking against a dynamic readline library)---if you are
+using gcc, you can do this by setting `CFLAGS=-static'.
 
 Here are the configure options you may want to use, in approximately
 descending order of usefulness.
@@ -55,7 +57,7 @@ descending order of usefulness.
 
 You can't use `--with-editline' and `--with-readline' together, of course,
 and if you have either of those you probably don't want to bother with
-`--enable-history'.
+`--with-history'.
 
   --prefix /path
 
@@ -66,9 +68,11 @@ and if you have either of those you probably don't want to bother with
 
   --disable-builtin-echo
 
-  By default, the `echo' command is builtin to rc for efficiency reasons.
-  It is the only builtin which is not essential, and purists may wish
-  to omit it.
+  By default, the `echo' command is builtin to rc for reasons of
+  efficiency and portability (of rc scripts).  It is the only builtin
+  which is not essential, and purists may wish to omit it.  Note that
+  `make trip' will fail if you disable builtin echo and your system's
+  `echo' does not understand `-n' to suppress newline.
 
   --with-addon
   --with-addon=foo.c
@@ -131,6 +135,23 @@ are building rc for multiple architectures.  All you need do is specify
 the path to the configure script in the first step.  Suitable `make's
 include GNU, and SunOS, but not Irix, nor UnixWare.
 
+COMPILATION WARNINGS
+
+If your C compiler is gcc, the option `-Wall' is turned on.  This may
+produce a few warnings.
+
+Warnings about "implicit declaration" of system functions may occur if
+your system's include files are deficient---they are usually harmless.
+
+There is a warning about "variable `n' might be clobbered" in walk.c.
+I'm not sure how serious this warning is, nor how to eliminate it.
+
+On some systems there are warnings about "passing arg 2 of `getgroups'
+from incompatible pointer type" in which.c.  I believe this is due to an
+incorrect declaration of `getgroups()' in those systems' header files.
+
+Any other warnings should be reported to the maintainer.
+
 OLD C
 
 rc needs an ISO C (89) compiler, or at least one that has a reasonable