Document VPATH = $(variable) issue in VPATH chapter.

* doc/autoconf.texi (Variables listed in VPATH): New node.
(Top, VPATH and Make): Adjust menus.
(Build Directories): Refer to it.
Prompted by report from Bruno Haible.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>

diff --git a/ChangeLog b/ChangeLog
index 64058cb864452f14bf992486d42f98e01c90aaad..73fc4834c457a8bd339114bcab3db9363b0f27b1 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-05-21  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
+
+       Document VPATH = $(variable) issue in VPATH chapter.
+       * doc/autoconf.texi (Variables listed in VPATH): New node.
+       (Top, VPATH and Make): Adjust menus.
+       (Build Directories): Refer to it.
+       Prompted by report from Bruno Haible.
+
 2009-05-19  Eric Blake  <ebb9@byu.net>
 
        Update uses of all-permissive license.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 7f0440800557aabc3f6e069d43e56ec6d0244eb2..a26b1b75e79ea749f8711a3b84506c783f88916c 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -519,6 +519,7 @@ Portable Make Programming
 
 @code{VPATH} and Make
 
+* Variables listed in VPATH::   @code{VPATH} must be literal on ancient hosts
 * VPATH and Double-colon::      Problems with @samp{::} on ancient hosts
 * $< in Explicit Rules::        @code{$<} does not work in ordinary rules
 * Automatic Rule Rewriting::    @code{VPATH} goes wild on Solaris
@@ -2953,9 +2954,8 @@ srcdir = @@srcdir@@
 VPATH = @@srcdir@@
 @end example
 
-Do not set @code{VPATH} to the value of another variable, for example
-@samp{VPATH = $(srcdir)}, because some versions of @command{make} do not do
-variable substitutions on the value of @code{VPATH}.
+Do not set @code{VPATH} to the value of another variable (@pxref{Variables
+listed in VPATH}.
 
 @command{configure} substitutes the correct value for @code{srcdir} when
 it produces @file{Makefile}.
@@ -18028,6 +18028,7 @@ Here are some known issues with some @code{VPATH}
 implementations.
 
 @menu
+* Variables listed in VPATH::   @code{VPATH} must be literal on ancient hosts
 * VPATH and Double-colon::      Problems with @samp{::} on ancient hosts
 * $< in Explicit Rules::        @code{$<} does not work in ordinary rules
 * Automatic Rule Rewriting::    @code{VPATH} goes wild on Solaris
@@ -18035,6 +18036,25 @@ implementations.
 * Make Target Lookup::          More details about @code{VPATH} lookup
 @end menu
 
+@node Variables listed in VPATH
+@subsection Variables listed in @code{VPATH}
+@cindex @code{VPATH} and variables
+@cindex variables and @code{VPATH}
+
+Do not set @code{VPATH} to the value of another variable, for example
+@samp{VPATH = $(srcdir)}, because some ancient versions of
+@command{make} do not do variable substitutions on the value of
+@code{VPATH}.  For example, use this
+
+@example
+srcdir = @@srcdir@@
+VPATH = @@srcdir@@
+@end example
+
+@noindent
+rather than @samp{VPATH = $(srcdir)}.  Note that with @acronym{GNU}
+Automake, there is no need to set this yourself.
+
 @node VPATH and Double-colon
 @subsection @code{VPATH} and Double-colon Rules
 @cindex @code{VPATH} and double-colon rules