30789: Add CONTINUE_ON_ERROR for old behaviour.

New behaviour is for scripts to exit on error instead of returning
to top level and executing the next command.

ChangeLog

@@ -1,5 +1,11 @@
 2012-11-15  Peter Stephenson  <p.w.stephenson@ntlworld.com>
 
+	* 30789: Doc/Zsh/grammar.yo, Doc/Zsh/options.yo, Src/hist.c,
+	Src/init.c, Src/options.c, Src/zsh.h, Test/A04redirect.zsh:  add
+	CONTINUE_ON_ERROR option for compatibility but turn it off:
+	scripts exit on an error instead of returning to the top-level
+	like interactive shells.
+
 	* 30800: Michal Halenka: Completion/Unix/Command/_arping: fix
 	option.
 
@@ -335,5 +341,5 @@
 
 *****************************************************
 * This is used by the shell to define $ZSH_PATCHLEVEL
-* $Revision: 1.5760 $
+* $Revision: 1.5761 $
 *****************************************************

Doc/Zsh/grammar.yo

@@ -438,7 +438,7 @@ where var(term) is at least one newline or tt(;).
 A short form of tt(select).
 )
 enditem()
-texinode(Reserved Words)(Comments)(Alternate Forms For Complex Commands)(Shell Grammar)
+texinode(Reserved Words)(Errors)(Alternate Forms For Complex Commands)(Shell Grammar)
 sect(Reserved Words)
 cindex(reserved words)
 findex(disable, use of)
@@ -451,7 +451,56 @@ select coproc nocorrect foreach end ! [[ { })
 
 Additionally, `tt(})' is recognized in any position if neither the
 tt(IGNORE_BRACES) option nor the tt(IGNORE_CLOSE_BRACES) option is set.
-texinode(Comments)(Aliasing)(Reserved Words)(Shell Grammar)
+texinode(Errors)(Comments)(Reserved Words)(Shell Grammar)
+sect(Errors)
+cindex(errors, handling of)
+Certain errors are treated as fatal by the shell: in an interactive
+shell, they cause control to return to the command line, and in a
+non-interactive shell they cause the shell to be aborted.  In older
+versions of zsh, a non-interactive shell running a script would not
+abort completely, but would resume execution at the next command to be
+read from the script, skipping the remainder of any functions or
+shell constructs such as loops or conditions; this somewhat illogical
+behaviour can be recovered by setting the option tt(CONTINUE_ON_ERROR).
+
+Fatal errors found in non-interactive shells include:
+startlist()
+list(Failure to parse shell options passed when invoking the shell)
+list(Failure to change options with the tt(set) builtin)
+list(Parse errors of all sorts, including failures to parse
+mathematical expressions)
+list(Failures to set or modify variable behaviour with tt(typeset),
+tt(local), tt(declare), tt(export), tt(integer), tt(float))
+list(Execution of incorrectly positioned loop control structures
+(tt(continue), tt(break)))
+list(Attempts to use regular expression with no regular expression
+module available)
+list(Disallowed operations when the tt(RESTRICTED) options is set)
+list(Failure to create a pipe needed for a pipeline)
+list(Failure to create a multio)
+list(Failure to autoload a module needed for a declared shell feature)
+list(Errors creating command or process substitutions)
+list(Syntax errors in glob qualifiers)
+list(File generation errors where not caught by the option tt(BAD_PATTERN))
+list(All bad patterns used for matching within case statements)
+list(File generation failures where not caused by tt(NO_MATCH) or
+list(All file generation errors where the pattern was used to create a
+multio)
+list(Memory errors where detected by the shell)
+list(Invalid subscripts to shell variables)
+list(Attempts to assign read-only variables)
+list(Logical errors with variables such as assignment to the wrong type)
+list(Use of invalid variable names)
+list(Errors in variable substitution syntax)
+list(Failure to convert characters in tt($')...tt(') expressions)
+similar options)
+endlist()
+
+If the tt(POSIX_BUILTINS) option is set, more errors associated with
+shell builtin commands are treated as fatal, as specified by the POSIX
+standard.
+
+texinode(Comments)(Aliasing)(Errors)(Shell Grammar)
 sect(Comments)
 cindex(comments)
 pindex(INTERACTIVE_COMMENTS, use of)

Doc/Zsh/options.yo

@@ -1733,6 +1733,22 @@ Make the tt(echo) builtin compatible with the BSD manref(echo)(1) command.
 This disables backslashed escape sequences in echo strings unless the
 tt(-e) option is specified.
 )
+pindex(CONTINUE_ON_ERROR)
+pindex(NO_CONTINUE_ON_ERROR)
+pindex(CONTINUEONERROR)
+pindex(NOCONTINUEONERROR)
+cindex(error, option to continue script on)
+item(tt(CONTINUE_ON_ERROR))(
+If a fatal error is encountered (see 
+ifnzman(noderef(Errors))\
+ifzman(the section ERRORS in zmanref(zshmisc))), and the code is running
+in a script, the shell will resume execution at the next statement
+in the script at the top level, in other words outside all functions
+or shell constructs such as loops and conditions.  This mimics the
+behaviour of interactive shells, where the shell returns to the
+line editor to read a new command; it was the normal behaviour in versions
+of zsh before 5.0.1.
+)
 pindex(CSH_JUNKIE_HISTORY)
 pindex(NO_CSH_JUNKIE_HISTORY)
 pindex(CSHJUNKIEHISTORY)

Src/hist.c

@@ -573,7 +573,7 @@ histsubchar(int c)
 		} else {
 		    herrflush();
 		    unqueue_signals();
-		    zerr("Ambiguous history reference");
+		    zerr("ambiguous history reference");
 		    return -1;
 		}
 

Src/init.c

@@ -1608,15 +1608,20 @@ zsh_main(UNUSED(int argc), char **argv)
 	 * We only do this at top level, because if we are
 	 * executing stuff we may refer to them by job pointer.
 	 */
+	int errexit = 0;
 	maybeshrinkjobtab();
 
 	do {
 	    /* Reset return from top level which gets us back here */
 	    retflag = 0;
 	    loop(1,0);
+	    if (errflag && !interact && !isset(CONTINUEONERROR)) {
+		errexit = 1;
+		break;
+	    }
 	} while (tok != ENDINPUT && (tok != LEXERR || isset(SHINSTDIN)));
-	if (tok == LEXERR) {
-	    /* Make sure a parse error exits with non-zero status */
+	if (tok == LEXERR || errexit) {
+	    /* Make sure a fatal error exits with non-zero status */
 	    if (!lastval)
 		lastval = 1;
 	    stopmsg = 1;

Src/options.c

@@ -113,6 +113,7 @@ static struct optname optns[] = {
 {{NULL, "combiningchars",     0},			 COMBININGCHARS},
 {{NULL, "completealiases",    0},			 COMPLETEALIASES},
 {{NULL, "completeinword",     0},			 COMPLETEINWORD},
+{{NULL, "continueonerror",    0},                        CONTINUEONERROR},
 {{NULL, "correct",	      0},			 CORRECT},
 {{NULL, "correctall",	      0},			 CORRECTALL},
 {{NULL, "cshjunkiehistory",   OPT_EMULATE|OPT_CSH},	 CSHJUNKIEHISTORY},

Src/zsh.h

@@ -1971,6 +1971,7 @@ enum {
     COMPLETEINWORD,
     CORRECT,
     CORRECTALL,
+    CONTINUEONERROR,
     CPRECEDENCES,
     CSHJUNKIEHISTORY,
     CSHJUNKIELOOPS,

Test/A04redirect.ztst

@@ -419,26 +419,26 @@
 >output
 ?zsh:.:2: no such file or directory: /nonexistent/nonexistent
 
+  $ZTST_testdir/../Src/zsh -f -o CONTINUE_ON_ERROR <<<'
+  readonly foo
+  foo=bar set output
+  echo output'
+0:failed assignment on posix special, CONTINUE_ON_ERROR
+>output
+?zsh: read-only variable: foo
+
   $ZTST_testdir/../Src/zsh -f <<<'
   readonly foo
   foo=bar set output
   echo output'
-0:failed assignment on posix special, NO_POSIX_BUILTINS
->output
+1:failed assignment on posix special, NO_CONTINUE_ON_ERROR
 ?zsh: read-only variable: foo
 
-  $ZTST_testdir/../Src/zsh -f -o POSIX_BUILTINS <<<'
-  readonly foo
-  foo=bar set output
-  echo output'
-1:failed assignment on posix special, POSIX_BUILTINS
-?zsh: read-only variable: foo
-
-  $ZTST_testdir/../Src/zsh -f -o POSIX_BUILTINS <<<'
+  $ZTST_testdir/../Src/zsh -f -o CONTINUE_ON_ERROR <<<'
   readonly foo
   foo=bar echo output
   echo output'
-0:failed assignment on non-posix-special, POSIX_BUILTINS
+0:failed assignment on non-posix-special, CONTINUE_ON_ERROR
 >output
 ?zsh: read-only variable: foo