[SCM] GNU Autoconf source repository branch, master, updated. v2.68-112-g28fd1f4

[Paul Eggert]

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- Log -----------------------------------------------------------------
commit 28fd1f4aa49c1180919a12ba0a793204fc1fcebe
Author: Paul Eggert <address@hidden>
Date:   Thu Jan 5 12:32:12 2012 -0800

    doc: mention Bash 2.03 bug with backslash-newline
    
    * doc/autoconf.texi (Invoking the Shell): New section.
    (Backslash-Newline-Empty): Rename from Backslash-Newline-Newline.
    Mention problem with Bash 2.03.

commit 3b4b3ee585509f69d72df963e73665f07b95923c
Author: Paul Eggert <address@hidden>
Date:   Thu Jan 5 11:00:45 2012 -0800

    doc: clarify sed buffer limit
    
    * doc/autoconf.texi (Limitations of Usual Tools):
    That 4000-byte limit applies to output and internal buffers, too.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog         |   11 +++++++++
 doc/autoconf.texi |   61 +++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 66 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 30312be..69df405 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2012-01-05  Paul Eggert  <address@hidden>
+
+       doc: mention Bash 2.03 bug with backslash-newline
+       * doc/autoconf.texi (Invoking the Shell): New section.
+       (Backslash-Newline-Empty): Rename from Backslash-Newline-Newline.
+       Mention problem with Bash 2.03.
+
+       doc: clarify sed buffer limit
+       * doc/autoconf.texi (Limitations of Usual Tools):
+       That 4000-byte limit applies to output and internal buffers, too.
+
 2012-01-03  Paul Eggert  <address@hidden>
 
        maint: update copyright year
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 72ff7f8..5c3feef 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -501,6 +501,7 @@ Dependencies Between Macros
 Portable Shell Programming
 
 * Shellology::                  A zoology of shells
+* Invoking the Shell::          Invoking the shell as a command
 * Here-Documents::              Quirks and tricks
 * File Descriptors::            FDs and redirections
 * Signal Handling::             Shells, signals, and headaches
@@ -520,7 +521,7 @@ Portable Make Programming
 * $< in Ordinary Make Rules::   $< in ordinary rules
 * Failure in Make Rules::       Failing portably in rules
 * Special Chars in Names::      Special Characters in Macro Names
-* Backslash-Newline-Newline::   Empty last lines in macro definitions
+* Backslash-Newline-Empty::     Empty lines after backslash-newline
 * Backslash-Newline Comments::  Spanning comments across line boundaries
 * Long Lines in Makefiles::     Line length limitations
 * Macros and Submakes::         @code{make macro=value} and submakes
@@ -15067,6 +15068,7 @@ subset described above, is fairly portable nowadays.  
Also please see
 
 @menu
 * Shellology::                  A zoology of shells
+* Invoking the Shell::          Invoking the shell as a command
 * Here-Documents::              Quirks and tricks
 * File Descriptors::            FDs and redirections
 * Signal Handling::             Shells, signals, and headaches
@@ -15205,6 +15207,28 @@ The default Mac OS X @command{sh} was originally Zsh; 
it was changed to
 Bash in Mac OS X 10.2.
 @end table
 
address@hidden Invoking the Shell
address@hidden Invoking the Shell
address@hidden invoking the shell
address@hidden shell invocation
+
+Bash 2.03 has a bug when invoked with the @option{-c} option: if the
+option-argument ends in backslash-newline, Bash incorrectly reports a
+syntax error.  The problem does not occur if a character follows the
+backslash:
+
address@hidden
+$ @kbd{$ bash -c 'echo foo \}
+> @kbd{'}
+bash: -c: line 2: syntax error: unexpected end of file
+$ @kbd{bash -c 'echo foo \}
+> @kbd{ '}
+foo
address@hidden example
+
address@hidden
address@hidden, for how this can cause problems in makefiles.
+
 @node Here-Documents
 @section Here-Documents
 @cindex Here-documents
@@ -19256,8 +19280,9 @@ $ @kbd{echo a | sed 's/x/x/;;s/x/x/'}
 sed: 1: "s/x/x/;;s/x/x/": invalid command code ;
 @end example
 
-Input should not have unreasonably long lines, since some @command{sed}
-implementations have an input buffer limited to 4000 bytes.  Likewise,
+Some @command{sed} implementations have a buffer limited to 4000 bytes,
+and this limits the size of input lines, output lines, and internal
+buffers that can be processed portably.  Likewise,
 not all @command{sed} implementations can handle embedded @code{NUL} or
 a missing trailing newline.
 
@@ -19662,7 +19687,7 @@ itself.
 * $< in Ordinary Make Rules::   $< in ordinary rules
 * Failure in Make Rules::       Failing portably in rules
 * Special Chars in Names::      Special Characters in Macro Names
-* Backslash-Newline-Newline::   Empty last lines in macro definitions
+* Backslash-Newline-Empty::     Empty lines after backslash-newline
 * Backslash-Newline Comments::  Spanning comments across line boundaries
 * Long Lines in Makefiles::     Line length limitations
 * Macros and Submakes::         @code{make macro=value} and submakes
@@ -19740,8 +19765,32 @@ this is test
 @noindent
 However, this problem is no longer of practical concern.
 
address@hidden Backslash-Newline-Newline
address@hidden Backslash-Newline-Newline in Make Macro Values
address@hidden Backslash-Newline-Empty
address@hidden Backslash-Newline Before Empty Lines
+
+A bug in Bash 2.03 can cause problems if a Make rule contains a
+backslash-newline followed by line that expands to nothing.
+For example, on Solaris 8:
+
address@hidden
+SHELL = /bin/bash
+EMPTY =
+foo:
+       touch foo \
+       $(EMPTY)
address@hidden example
+
address@hidden
+executes
+
address@hidden
+/bin/bash -c 'touch foo \
+'
address@hidden example
+
address@hidden
+which fails with a syntax error, due to the Bash bug.  To avoid this
+problem, avoid nullable macros in the last line of a multiline command.
 
 @c  This has been seen on ia64 hpux 11.20, and on one hppa hpux 10.20,
 @c  but another hppa hpux 10.20 didn't have it.  Bob Proulx


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