From: Alexandre Duret-Lutz <adl@gnu.org>
Date: Thu, 25 Jul 2002 21:00:45 +0000 (+0000)
Subject: * doc/autoconf.texi (Limitations of Make): Escaped newlines in
X-Git-Tag: AUTOCONF-2.53c~44
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e5dcc69a98b34cd57b2456d80cce2fdd0db20c4;p=thirdparty%2Fautoconf.git

* doc/autoconf.texi (Limitations of Make): Escaped newlines in
comments do not always work. Never trust the exit status of
`make -k'.
---

diff --git a/ChangeLog b/ChangeLog
index 6d03b2397..b97679cfb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,10 +1,16 @@
+2002-07-25  Alexandre Duret-Lutz  <duret_g@epita.fr>
+
+	* doc/autoconf.texi (Limitations of Make): Escaped newlines in
+	comments do not always work. Never trust the exit status of
+	`make -k'.
+
 2002-07-23  Paul Eggert  <eggert@twinsun.com>
 
 	* lib/m4sugar/m4sh.m4 (_AS_PATH_SEPARATOR_PREPARE):
 	Use PATH="/nonexistent;.", not PATH=".;.", as FreeBSD ksh2002
 	apparently treats PATH="nonexistent" as if it contained ".".
 	Bug reported by Stefan `Sec' Zehl.
-	
+
 2002-07-22  Alexandre Duret-Lutz  <duret_g@epita.fr>
 
 	* doc/autoconf.texi (Limitations of Make): Mention the special
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 23bf77064..d99f8c8a8 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -10276,6 +10276,44 @@ test:
 shows @code{FOO} equal to @code{one BAR = two}.  Other Makes sensibly
 let a backslash continue only to the immediately following line.
 
+@item Escaped newline in comments
+
+According to @sc{posix}, Makefile comments start with @code{#} and
+continue until an unescaped newline is reached.
+
+@example
+% @kbd{cat Makefile}
+# A = foo \
+      bar \
+      baz
+
+all:
+        @@echo ok
+% @kbd{make}   # GNU make
+ok
+@end example
+
+@noindent
+However in Real World this is not always the case.  Some implementations
+discards anything from @code{#} up to the end of line, ignoring any
+trailing backslash.
+
+@example
+% @kbd{pmake}  # BSD make
+"Makefile", line 3: Need an operator
+Fatal errors encountered -- cannot continue
+@end example
+
+@noindent
+Therefore, if you want to comment a multi-line definition, prefix each
+line with @code{#}, not only the first.
+
+@example
+# A = foo \
+#     bar \
+#     baz
+@end example
+
 @item @code{make macro=value} and sub-@command{make}s.
 
 A command-line variable definition such as @code{foo=bar} overrides any
@@ -10421,6 +10459,27 @@ echo World
 World
 @end example
 
+@item @code{make -k}
+@cindex @code{make -k}
+
+Do not rely on the exit status of @code{make -k}.  Some implementations
+reflect whether they encountered an error in their exit status; other
+implementations always succeed.
+
+@example
+% @kbd{cat Makefile}
+all:
+        false
+% @kbd{make -k; echo exit status: $?}    # GNU make
+false
+make: *** [all] Error 1
+exit status: 2
+% @kbd{pmake -k; echo exit status: $?}   # BSD make
+false
+*** Error code 1 (continuing)
+exit status: 0
+@end example
+
 @item @code{VPATH}
 @cindex @code{VPATH}