Factor load functionality into include builtin.include-dso

* m4/module.c (m4__module_open): Instead of calling lt_dlopenext
right away, use the preload hint first incase path searching has
been disabled by POSIXLY_CORRECT.  Otherwise fallback to a
manual path search to override libltdl's algorithm.
* m4/m4module.h: Adjust.
* m4/path.c (FILE_SUFFIXES): Order to try suffixes in our path
search algorithm.
(NO_SUFFIXES): Alternatively, how to to search a path without
adding file suffixes.
(m4_path_search): Add a new suffixes parameter defaulting to
NO_SUFFIXES.  Adjust all callers.
(m4_load_filename): New generic load function that tries to
open a matched file first as a module, and if that fails fall
back to as (possibly frozen) m4 input.
(m4_fopen): New function with close on exec functionality.
* modules/m4.c (include, sinclude): Use m4_load_filename to
overload these builtins to work with modules too.
* modules/load.c (load): Removed this builtin.
* src/main.c: Remove Dynamic loading features section, and
M4MODPATH support.
(long_options): Remove "load-module", "unload-module" and
"module-directory" options.
(OPTSTRING): Remove 'M' and 'm' options.
(process_file): Use m4_load_filename to support module names
on the command line.
* Makefile.am (TESTS_ENVIRONMENT): No need for abs_top_builddir
any more.
* doc/m4.texinfo: Update examples.
(Dynamic loading features, Load): Removed.
(Command line files): Describe how non-option arguments are
treated to try to find a matching macro file or dso.
(Include): Describe additional dso loading features if a
suitable text file cannot be found.
(Modules): Updated.
* tests/builtins.at, tests/m4.in, tests/modules.at,
tests/options.at: Adjust test cases and calling conventions
to new semantics.
* NEWS: Updated.

1 files changed, 18 insertions, 4 deletions

diff --git a/NEWS b/NEWS
index 35440ee0..ce30bbdc 100644
--- a/NEWS
+++ b/NEWS
@@ -76,13 +76,18 @@ promoted to 2.0.
     `--trace', allow more control over macro tracing from the command line
     between input files.
 
-*** New `--unload-module' command-line option allows more control over
-    dynamic modules from the command line.  Also, `-m'/`--load-module' now
-    acts between input files.
-
 *** New `--warnings' command-line option re-enables warnings, overriding
     `-Q'/`--quiet'/`--silent', allowing warnings even when POSIXLY_CORRECT.
 
+*** When GNU extensions are enabled, any command line arguments that wauld
+    have been interpreted as input file names with previous releases are
+    still searched for as before, but will first attempt to be loaded as
+    compiled modules before falling back on loading as m4 input.  In
+    POSIXLY_CORRECT mode, only m4 input files in the current directory can
+    be loaded.
+
+*** Any command line arguments that previously had to name input files
+
 ** POSIX conformance
 
 *** The `defn' builtin now allows any number of arguments, as POSIX requires.
@@ -96,6 +101,9 @@ promoted to 2.0.
 *** The experimental `epatsubst' and `eregexp' builtins have been removed
     in favor of a new `changeresyntax' builtin.
 
+*** The `load' builtin, introduced in previous betas has been removed in
+    lieu of richer `include' and `sinclude' functionality.
+
 ** New builtins
 
 *** New `changeresyntax' builtin allows programmatic setting of the default
@@ -175,6 +183,12 @@ promoted to 2.0.
 *** The `eval' and `mpeval' builtins now support the following new
     operators: `>>>', `\', `?:', and  `,'.
 
+*** When GNU extensions are enabled, the `include' and `sinclude' builtins
+    continue to search directories one at a time, but will first attempt to
+    load arguments as compiled modules and then as m4 input before moving
+    to the next directory in the search path.  In POSIXLY_CORRECT mode,
+    only m4 input in the current directory can be loaded.
+
 *** The `maketemp' builtin now always warns that it is obsolete, even in GNU
     mode where it uses the same secure algorithm as `mkstemp', because of
     the recommendation of POSIX to obsolete `maketemp' as inherently