Subject: bug#41914: [PATCH] Propagate return value of auto-loaded command

From: Tom de Vries <[email-masked]>
Date: Wed, 17 Jun 2020 13:40:40 +0200

Hi,

I think I found a bug in proc unknown in lib/framework.exp.

Patch describing the problem and fixing it attached below.

Thanks,
- Tom
Propagate return value of auto-loaded command

Consider a library file foo.tcl:
...
$ cat lib/foo.tcl
proc foo { } {
    return "foo-return"
}
...
and a test-case test.tcl:
...
$ cat test.tcl
\#!/usr/bin/tclsh

auto_mkindex lib *.tcl

lappend auto_path [pwd]/lib

set res [foo]
puts "RES: $res"
...
which gives us:
...
$ ./test.tcl
RES: foo-return
...

When overriding the ::unknown command using:
...
rename ::unknown ::tcl_unknown
proc unknown args {
    if {[catch {uplevel 1 ::tcl_unknown $args} msg]} {
        puts "ERROR: proc \"$args\" does not exist."
        exit
    }
}
...
we have instead:
...
$ ./test.tcl
RES:
...

What is missing, is the propagation of the return value of foo, like this:
...
         puts "ERROR: proc \"$args\" does not exist."
         exit
     }
-}
+} else {
+    return $msg
+}
...

Fix unknown in lib/framework.exp accordingly.

ChangeLog:

2020-06-17  Tom de Vries  <[email-masked]>

	* lib/framework.exp (unknown): Propagate return value of auto-loaded
	command.

---
 lib/framework.exp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/framework.exp b/lib/framework.exp
index e6ce197..c9875d2 100644
--- a/lib/framework.exp
+++ b/lib/framework.exp
@@ -272,6 +272,9 @@ proc unknown args {
 	}
 	set exit_status 2
 	log_and_exit
+    } else {
+	# Propagate return value.
+	return $msg
     }
 }