Change syntax of AM_VARNISHAPI macro call.

The macro takes up to two arguments: oldest supported and newest
tested Varnish versions.

2 files changed, 39 insertions, 20 deletions

diff --git a/README b/README
index 3299d76..68c2379 100644
--- a/README
+++ b/README
@@ -162,19 +162,27 @@ The following command was used to create initial set up of the
 
 The =AM_VARNISHAPI= macro is used in =configure.ac= to check whether
 the varnish API components (header files and libraries) are installed
-and are of sufficiently modern version. The macro is invoked with one
-optional argument - the oldest required version of the API:
+and are of sufficiently modern version. The macro is invoked with at
+most two arguments, both of which are optional:
 
 #+BEGIN_SRC autoconf
- AM_VARNISHAPI([VERSION])
+ AM_VARNISHAPI([MIN-VERSION],[MAX-VERSION])
 #+END_SRC
 
-If =VERSION= argument is supplied, the macro checks if varnish API
-version is the same or newer than that version number.  Otherwise, if 
-package version string ends in -N.N.N, where N stands for a decimal
-digit, it checks if varnish API version is at least N.N.N. 
-If API is older, it emits error message and aborts. If the version is 
-newer, a warning message is emitted at the end of configure.
+The =MIN-VERSION= argument specifies the oldest supported version of 
+Varnish API. If the API is older than that, an error message will
+be emitted and configuration will be aborted.
+
+The =MAX-VERSION= argument specifies the newest version of Varnish API
+for which the package was tested. If the API is newer than that, a
+warning message will be emitted at the end of the run to inform the
+user about the fact. If MAX-VERSION is omitted, no such test is made.
+
+If the macro is called without arguments, its behavior depends on
+the package version (as specified in the AC_INIT macro call). If
+the version ends in -N.N.N (where _N_ stands for a decimal
+digit), the macro behaves as if it were invoked as
+~AM_VARNISHAPI(N.N.N)~. Otherwise, no version checking is performed.
 
 The ~AM_VARNISHAPI~ macro sets the following configuration variables:
 
diff --git a/varnishapi.m4 b/varnishapi.m4
index 895b922..bc8e2e4 100644
--- a/varnishapi.m4
+++ b/varnishapi.m4
@@ -47,13 +47,18 @@ m4_define([VAPI_CHECK_VER],[
   fi
 ])])
 
-## AM_VARNISHAPI([VERSION])
+## AM_VARNISHAPI([MIN-VERSION],[MAX-VERSION])
 ## Tests if the programs and libraries needed for compiling a varnish
-## module are present. If VERSION argument is supplied, checks if varnish API
-## version is the same or newer than that.  Otherwise, if package version
-## string ends in -N.N.N, where N stands for a decimal digit, checks if varnish
-## API version is at least N.N.N. If API is older, emits error message and
-## aborts. If it is newer, emits a warning message at the end of configure.
+## module are present. If MIN-VERSION argument is supplied, checks if
+## varnish API version is the same or newer than that. If it is older,
+## emits error message and aborts. Otherwise, if MAX-VERSION is specified
+## checks varnish API version against that. If the version is newer than
+## both MAX-VERSION, a warning message to that effect will be emitted at
+## the end of configure.
+##
+## If no arguments are given, and the package version string ends in -N.N.N,
+## (where N stands for a decimal digit), the macro behaves as if it were
+## called as AM_VARNISHAPI([N.N.N]).
 ##
 ## Sets the following configuration variables:
 ##
@@ -96,11 +101,17 @@ AC_DEFUN([AM_VARNISHAPI],
     IFS='.'
     varnishapi_version $v
     IFS=$save_IFS
-    VAPI_CHECK_VER(m4_if([$1],,
-     [m4_pushdef([ver],[m4_bpatsubst(AC_PACKAGE_VERSION,[.*-\([0-9]\)\.\([0-9]\)\.\([0-9]\)$],[m4_quote(\1,\2,\3)])])dnl
-m4_if(ver,AC_PACKAGE_VERSION,,[m4_unquote(ver)])dnl
-m4_popdef([ver])],
-     [m4_unquote(m4_split([$1],\.))]))
+
+    m4_pushdef([ver],[m4_bpatsubst(AC_PACKAGE_VERSION,[.*-\([0-9]\.[0-9]\.[0-9]\)$],[\1])])
+
+    VAPI_CHECK_VER(m4_unquote(m4_split(m4_if([ver],AC_PACKAGE_VERSION,[$1],[$1],,[ver],[$1]),\.)))
+
+    m4_if([$2],,[m4_if(ver,[AC_PACKAGE_VERSION],[# Suppress the warning message
+    varnishapi_version_diff=same])],dnl
+    [if test "$varnishapi_version_diff" = newer; then
+       VAPI_CHECK_VER(m4_unquote(m4_split([$2],\.)))
+     fi])
+    m4_popdef([ver])
   else
     AC_MSG_ERROR([unknown varnishapi version])
   fi