Update to autoconf 2.50 version.

1 files changed, 80 insertions, 36 deletions

diff --git a/INSTALL b/INSTALL
index b42a17ac4..666ffd9f8 100644
--- a/INSTALL
+++ b/INSTALL
@@ -8,20 +8,27 @@ various system-dependent variables used during compilation.  It uses
 those values to create a `Makefile' in each directory of the package.
 It may also create one or more `.h' files containing system-dependent
 definitions.  Finally, it creates a shell script `config.status' that
-you can run in the future to recreate the current configuration, a file
-`config.cache' that saves the results of its tests to speed up
-reconfiguring, and a file `config.log' containing compiler output
-(useful mainly for debugging `configure').
+you can run in the future to recreate the current configuration, and a
+file `config.log' containing compiler output (useful mainly for
+debugging `configure').
+
+   It can also use an optional file (typically called `config.cache'
+and enabled with `--cache-file=config.cache' or simply `-C') that saves
+the results of its tests to speed up reconfiguring.  (Caching is
+disabled by default to prevent problems with accidental use of stale
+cache files.)
 
    If you need to do unusual things to compile the package, please try
 to figure out how `configure' could check whether to do them, and mail
 diffs or instructions to the address given in the `README' so they can
-be considered for the next release.  If at some point `config.cache'
-contains results you don't want to keep, you may remove or edit it.
+be considered for the next release.  If you are using the cache, and at
+some point `config.cache' contains results you don't want to keep, you
+may remove or edit it.
 
-   The file `configure.in' is used to create `configure' by a program
-called `autoconf'.  You only need `configure.in' if you want to change
-it or regenerate `configure' using a newer version of `autoconf'.
+   The file `configure.ac' (or `configure.in') is used to create
+`configure' by a program called `autoconf'.  You only need
+`configure.ac' if you want to change it or regenerate `configure' using
+a newer version of `autoconf'.
 
 The simplest way to compile this package is:
 
@@ -55,14 +62,15 @@ Compilers and Options
 =====================
 
    Some systems require unusual options for compilation or linking that
-the `configure' script does not know about.  You can give `configure'
-initial values for variables by setting them in the environment.  Using
-a Bourne-compatible shell, you can do that on the command line like
-this:
-     CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure
+the `configure' script does not know about.  Run `./configure --help'
+for details on some of the pertinent environment variables.
+
+   You can give `configure' initial values for variables by setting
+them in the environment.  You can do that on the command line like this:
 
-Or on systems that have the `env' program, you can do it like this:
-     env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure
+     ./configure CC=c89 CFLAGS=-O2 LIBS=-lposix
+
+   *Note Environment Variables::, for more details.
 
 Compiling For Multiple Architectures
 ====================================
@@ -75,7 +83,7 @@ directory where you want the object files and executables to go and run
 the `configure' script.  `configure' automatically checks for the
 source code in the directory that `configure' is in and in `..'.
 
-   If you have to use a `make' that does not supports the `VPATH'
+   If you have to use a `make' that does not support the `VPATH'
 variable, you have to compile the package for one architecture at a time
 in the source code directory.  After you have installed the package for
 one architecture, use `make distclean' before reconfiguring for another
@@ -122,22 +130,36 @@ you can use the `configure' options `--x-includes=DIR' and
 Specifying the System Type
 ==========================
 
-   There may be some features `configure' can not figure out
+   There may be some features `configure' cannot figure out
 automatically, but needs to determine by the type of host the package
 will run on.  Usually `configure' can figure that out, but if it prints
-a message saying it can not guess the host type, give it the
-`--host=TYPE' option.  TYPE can either be a short name for the system
-type, such as `sun4', or a canonical name with three fields:
+a message saying it cannot guess the host type, give it the
+`--build=TYPE' option.  TYPE can either be a short name for the system
+type, such as `sun4', or a canonical name which has the form:
+
      CPU-COMPANY-SYSTEM
 
-See the file `config.sub' for the possible values of each field.  If
+where SYSTEM can have one of these forms:
+
+     OS
+     KERNEL-OS
+
+   See the file `config.sub' for the possible values of each field.  If
 `config.sub' isn't included in this package, then this package doesn't
 need to know the host type.
 
-   If you are building compiler tools for cross-compiling, you can also
+   If you are _building_ compiler tools for cross-compiling, you should
 use the `--target=TYPE' option to select the type of system they will
-produce code for and the `--build=TYPE' option to select the type of
-system on which you are compiling the package.
+produce code for.
+
+   If you want to _use_ a cross compiler, that generates code for a
+platform different from the build platform, you should specify the host
+platform (i.e., that on which the generated programs will eventually be
+run) with `--host=TYPE'.  In this case, you should also specify the
+build platform with `--build=TYPE', because, in this case, it may not
+be possible to guess the build platform (it sometimes involves
+compiling and running simple test programs, and this can't be done if
+the compiler is a cross compiler).
 
 Sharing Defaults
 ================
@@ -150,20 +172,44 @@ default values for variables like `CC', `cache_file', and `prefix'.
 `CONFIG_SITE' environment variable to the location of the site script.
 A warning: not all `configure' scripts look for a site script.
 
-Operation Controls
-==================
+Environment Variables
+=====================
+
+   Variables not defined in a site shell script can be set in the
+environment passed to configure.  However, some packages may run
+configure again during the build, and the customized values of these
+variables may be lost.  In order to avoid this problem, you should set
+them in the `configure' command line, using `VAR=value'.  For example:
+
+     ./configure CC=/usr/local2/bin/gcc
+
+will cause the specified gcc to be used as the C compiler (unless it is
+overridden in the site shell script).
+
+`configure' Invocation
+======================
 
    `configure' recognizes the following options to control how it
 operates.
 
-`--cache-file=FILE'
-     Use and save the results of the tests in FILE instead of
-     `./config.cache'.  Set FILE to `/dev/null' to disable caching, for
-     debugging `configure'.
-
 `--help'
+`-h'
      Print a summary of the options to `configure', and exit.
 
+`--version'
+`-V'
+     Print the version of Autoconf used to generate the `configure'
+     script, and exit.
+
+`--cache-file=FILE'
+     Enable the cache: use and save the results of the tests in FILE,
+     traditionally `config.cache'.  FILE defaults to `/dev/null' to
+     disable caching.
+
+`--config-cache'
+`-C'
+     Alias for `--cache-file=config.cache'.
+
 `--quiet'
 `--silent'
 `-q'
@@ -175,8 +221,6 @@ operates.
      Look for the package's source code in directory DIR.  Usually
      `configure' can determine that directory automatically.
 
-`--version'
-     Print the version of Autoconf used to generate the `configure'
-     script, and exit.
+`configure' also accepts some other, not widely useful, options.  Run
+`configure --help' for more details.
 
-`configure' also accepts some other, not widely useful, options.