[Tcl-bugs] [ tcl-Bugs-1584674 ] where has the syntax error detection gone

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Bugs item #1584674, was opened at 2006-10-25 20:09
Message generated for change (Comment added) made by dkf
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>Category: 46. Bytecode Compiler
>Group: current: 8.5a5
Status: Open
Resolution: None
>Priority: 3
Private: No
Submitted By: Peter MacDonald (pcmacdon)
>Assigned to: miguel sofer (msofer)
Summary: where has the syntax error detection gone

Initial Comment:
I was trying out 8.5a5 thinking that it's new compiled
switch feature would improve Tcl's detection of syntax
errors in switch arms, but instead found not only 
is it unchanged, but that the basic error detection of
"if" is now gone.  For example the following script
causes 8.3 and 8.4 to barf, but is perfectly legal
in 8.5:

  proc bar var {
    if {$var == "acorn"} {
      set a b c
    }
  }
  bar a

Ditto for 

  proc bar var {
    if {$var == "acorn"} {
      set a [b c
    }
  }


The "no errors til you execute it" policy means
you need nearly perfect code coverage testing
to use Tcl with any confidence.


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>Comment By: Donal K. Fellows (dkf)
Date: 2006-10-25 22:27

Message:
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user_id=79902

Because you can do some horrible hacks like this now:

  rename if if_
  proc if args {
     foreach a $args {puts $a}
  }
  bar var
  rename if {}
  rename if_ if

OK, that's rather odd code, but it's legal. If you want
static syntax checking, use a third-party tool like Nagelfar.

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