Modified processing of $::errorInfo by [unknown] when the auto-loaded command

throws an error to better cover the tracks of auto-loading.
[Bug 219280, Patch 403551]

3 files changed, 100 insertions, 19 deletions

diff --git a/ChangeLog b/ChangeLog
index 09cb05e..a6eae95 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2001-04-06  Don Porter  <dgp@users.sourceforge.net>
+
+	* library/init.tcl:
+	* tests/init.test:  Modified processing of $::errorInfo by
+	[unknown] when the auto-loaded command throws an error to better
+	cover the tracks of auto-loading.  [Bug 219280, Patch 403551]
+
 2001-04-06  Donal K. Fellows  <fellowsd@cs.man.ac.uk>
 
 	* doc/read.n: Added section on "USE WITH SERIAL PORTS" to resolve
diff --git a/library/init.tcl b/library/init.tcl
index b6ba69f..644fba3 100644
--- a/library/init.tcl
+++ b/library/init.tcl
@@ -3,7 +3,7 @@
 # Default system startup file for Tcl-based applications.  Defines
 # "unknown" procedure and auto-load facilities.
 #
-# RCS: @(#) $Id: init.tcl,v 1.44 2000/12/11 04:17:38 dgp Exp $
+# RCS: @(#) $Id: init.tcl,v 1.45 2001/04/06 17:57:31 dgp Exp $
 #
 # Copyright (c) 1991-1993 The Regents of the University of California.
 # Copyright (c) 1994-1996 Sun Microsystems, Inc.
@@ -203,14 +203,48 @@ proc unknown args {
 	    set code [catch {uplevel 1 $args} msg]
 	    if {$code ==  1} {
 		#
-		# Strip the last five lines off the error stack (they're
-		# from the "uplevel" command).
+		# Compute stack trace contribution from the [uplevel].
+		# Note the dependence on how Tcl_AddErrorInfo, etc. 
+		# construct the stack trace.
 		#
-
-		set new [split $errorInfo \n]
-		set new [join [lrange $new 0 [expr {[llength $new] - 6}]] \n]
+		set cinfo $args
+		if {[string length $cinfo] > 150} {
+		    set cinfo "[string range $cinfo 0 149]..."
+		}
+		append cinfo "\"\n    (\"uplevel\" body line 1)"
+		append cinfo "\n    invoked from within"
+		append cinfo "\n\"uplevel 1 \$args\""
+		#
+		# Try each possible form of the stack trace
+		# and trim the extra contribution from the matching case
+		#
+		set expect "$msg\n    while executing\n\"$cinfo"
+		if {$errorInfo eq $expect} {
+		    #
+		    # The stack has only the eval from the expanded command
+		    # Do not generate any stack trace here.
+		    #
+		    return -code error -errorcode $errorCode $msg
+		}
+		#
+		# Stack trace is nested, trim off just the contribution
+		# from the extra "eval" of $args due to the "catch" above.
+		#
+		set expect "\n    invoked from within\n\"$cinfo"
+		set exlen [string length $expect]
+		set eilen [string length $errorInfo]
+		set i [expr {$eilen - $exlen - 1}]
+		set einfo [string range $errorInfo 0 $i]
+		#
+		# For now verify that $errorInfo consists of what we are about
+		# to return plus what we expected to trim off.
+		#
+		if {$errorInfo ne "$einfo$expect"} {
+		    error "Tcl bug: unexpected stack trace in \"unknown\"" {} \
+			[list CORE UNKNOWN BADTRACE $expect $errorInfo"]
+		}
 		return -code error -errorcode $errorCode \
-			-errorinfo $new $msg
+			-errorinfo $einfo $msg
 	    } else {
 		return -code $code $msg
 	    }
diff --git a/tests/init.test b/tests/init.test
index 46f4429..c31412b 100644
--- a/tests/init.test
+++ b/tests/init.test
@@ -10,7 +10,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: init.test,v 1.7 2000/05/03 00:14:36 hobbs Exp $
+# RCS: @(#) $Id: init.test,v 1.8 2001/04/06 17:57:32 dgp Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     package require tcltest
@@ -149,21 +149,61 @@ test init-3.0 {random stuff in the auto_index, should still work} {
     foo:::bar::blah
 } 1
 
+# Tests that compare the error stack trace generated when autoloading
+# with that generated when no autoloading is necessary.  Ideally they
+# should be the same.
+
+set count 0
+foreach arg {
+		c
+                {argument
+                which spans
+                multiple lines}
+                {argument which is all on one line but which is of such great length that the Tcl C library will truncate it when appending it onto the global error stack}
+                {argument which spans multiple lines
+                and is long enough to be truncated and
+"               <- includes a false lead in the prune point search
+                and must be longer still to force truncation}
+                {contrived example: rare circumstance 
+		where the point at which to prune the
+		error stack cannot be uniquely determined.
+		foo bar foo
+"}
+                {contrived example: rare circumstance 
+		where the point at which to prune the
+		error stack cannot be uniquely determined.
+		foo bar
+"}
+	} {
+
+    test init-4.$count.0 {::errorInfo produced by [unknown]} {
+	auto_reset
+	catch {parray a b $arg}
+	set first $::errorInfo
+	catch {parray a b $arg}
+	set second $::errorInfo
+	string equal $first $second
+    } 1
+
+    test init-4.$count.1 {::errorInfo produced by [unknown]} {
+	auto_reset
+	namespace eval junk [list array set $arg [list 1 2 3 4]]
+	trace variable ::junk::$arg r \
+		"[list error [subst {Variable \"$arg\" is write-only}]] ;# "
+	catch {parray ::junk::$arg}
+	set first $::errorInfo
+	catch {parray ::junk::$arg}
+	set second $::errorInfo
+	string equal $first $second
+    } 1
+
+    incr count
 }
 
+}	;#  End of [interp eval $testInterp]
+
 # cleanup
 interp delete $testInterp
 ::tcltest::cleanupTests
 return
 
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