Re: [ID 20000123.003] [BUG our() 5.005_63] Lexical scoping problems.

[Gurusamy Sarathy <gsar@ActiveState.com>]

On Sun, 23 Jan 2000 21:38:42 PST, I wrote:
>On Mon, 24 Jan 2000 00:01:21 EST, Michael G Schwern wrote:
>>I've bumped into a few basic scoping problems with our():
>>
>>our $a = "Outer";
>>{
>>        our $a = "Inner";
>>        print "$a\n";
>>}
>>print "$a\n";
>>
>>$a is "Inner" in both places.
>
>Of course it is; both $a's are aliases to the same global.  our doesn't
>automatically local()ize.  You need to explicitly spell that
>C<local our $a = "Inner"> if that's what you want.
>
>I think the "our" variable masks ... warning had better be extended
>to warn on this case.

    % ./perl -Ilib -Mdiagnostics -we 'our $foo; { our $foo; }'
    "our" variable $foo redeclared at -e line 1 (#1)
	
	(W) You seem to have already declared the same global once before in the
	current lexical scope.
	
    (Did you mean "local" instead of "our"?) (#2)
	
	(W) Remember that "our" does not localize the declared global variable.
	You have declared it again in the same lexical scope, which seems superfluous.


Sarathy
gsar@ActiveState.com
-----------------------------------8<-----------------------------------
Change 4891 by gsar@auger on 2000/01/25 20:22:01

	produce redeclaration warning on C<our $foo; { our $foo; ... }>

Affected files ...

... //depot/perl/op.c#246 edit
... //depot/perl/pod/perldelta.pod#134 edit
... //depot/perl/pod/perldiag.pod#118 edit
... //depot/perl/t/pragma/strict-vars#9 edit

Differences ...

==== //depot/perl/op.c#246 (text) ====
Index: perl/op.c
--- perl/op.c.~1~	Tue Jan 25 12:29:52 2000
+++ perl/op.c	Tue Jan 25 12:29:52 2000
@@ -153,22 +153,39 @@
     }
     if (ckWARN(WARN_UNSAFE) && AvFILLp(PL_comppad_name) >= 0) {
 	SV **svp = AvARRAY(PL_comppad_name);
-	for (off = AvFILLp(PL_comppad_name); off > PL_comppad_name_floor; off--) {
+	HV *ourstash = (PL_curstash ? PL_curstash : PL_defstash);
+	PADOFFSET top = AvFILLp(PL_comppad_name);
+	for (off = top; off > PL_comppad_name_floor; off--) {
 	    if ((sv = svp[off])
 		&& sv != &PL_sv_undef
 		&& (SvIVX(sv) == PAD_MAX || SvIVX(sv) == 0)
+		&& (PL_in_my != KEY_our
+		    || ((SvFLAGS(sv) & SVpad_OUR) && GvSTASH(sv) == ourstash))
 		&& strEQ(name, SvPVX(sv)))
 	    {
-		if (PL_in_my != KEY_our
-		    || GvSTASH(sv) == (PL_curstash ? PL_curstash : PL_defstash))
+		Perl_warner(aTHX_ WARN_UNSAFE,
+		    "\"%s\" variable %s masks earlier declaration in same %s", 
+		    (PL_in_my == KEY_our ? "our" : "my"),
+		    name,
+		    (SvIVX(sv) == PAD_MAX ? "scope" : "statement"));
+		--off;
+		break;
+	    }
+	}
+	if (PL_in_my == KEY_our) {
+	    while (off >= 0 && off <= top) {
+		if ((sv = svp[off])
+		    && sv != &PL_sv_undef
+		    && ((SvFLAGS(sv) & SVpad_OUR) && GvSTASH(sv) == ourstash)
+		    && strEQ(name, SvPVX(sv)))
 		{
 		    Perl_warner(aTHX_ WARN_UNSAFE,
-			"\"%s\" variable %s masks earlier declaration in same %s", 
-			(PL_in_my == KEY_our ? "our" : "my"),
-			name,
-			(SvIVX(sv) == PAD_MAX ? "scope" : "statement"));
+			"\"our\" variable %s redeclared", name);
+		    Perl_warner(aTHX_ WARN_UNSAFE,
+			"(Did you mean \"local\" instead of \"our\"?)\n");
+		    break;
 		}
-		break;
+		--off;
 	    }
 	}
     }

==== //depot/perl/pod/perldelta.pod#134 (text) ====
Index: perl/pod/perldelta.pod
--- perl/pod/perldelta.pod.~1~	Tue Jan 25 12:29:52 2000
+++ perl/pod/perldelta.pod	Tue Jan 25 12:29:52 2000
@@ -1549,11 +1549,6 @@
 
 =over 4
 
-=item "my sub" not yet implemented
-
-(F) Lexically scoped subroutines are not yet implemented.  Don't try that
-yet.
-
 =item "%s" variable %s masks earlier declaration in same %s
 
 (W) A "my" or "our" variable has been redeclared in the current scope or statement,
@@ -1562,6 +1557,16 @@
 until the end of the scope or until all closure referents to it are
 destroyed.
 
+=item "my sub" not yet implemented
+
+(F) Lexically scoped subroutines are not yet implemented.  Don't try that
+yet.
+
+=item "our" variable %s redeclared
+
+(W) You seem to have already declared the same global once before in the
+current lexical scope.
+
 =item '!' allowed only after types %s
 
 (F) The '!' is allowed in pack() and unpack() only after certain types.
@@ -1802,6 +1807,11 @@
 
 See Server error.
 
+=item Did you mean "local" instead of "our"?
+
+(W) Remember that "our" does not localize the declared global variable.
+You have declared it again in the same lexical scope, which seems superfluous.
+
 =item Document contains no data
 
 See Server error.

==== //depot/perl/pod/perldiag.pod#118 (text) ====
Index: perl/pod/perldiag.pod
--- perl/pod/perldiag.pod.~1~	Tue Jan 25 12:29:52 2000
+++ perl/pod/perldiag.pod	Tue Jan 25 12:29:52 2000
@@ -31,6 +31,14 @@
 
 =over 4
 
+=item "%s" variable %s masks earlier declaration in same %s
+
+(W) A "my" or "our" variable has been redeclared in the current scope or statement,
+effectively eliminating all access to the previous instance.  This is almost
+always a typographical error.  Note that the earlier variable will still exist
+until the end of the scope or until all closure referents to it are
+destroyed.
+
 =item "my sub" not yet implemented
 
 (F) Lexically scoped subroutines are not yet implemented.  Don't try that
@@ -42,19 +50,16 @@
 to try to declare one with a package qualifier on the front.  Use local()
 if you want to localize a package variable.
 
-=item "%s" variable %s masks earlier declaration in same %s
-
-(W) A "my" or "our" variable has been redeclared in the current scope or statement,
-effectively eliminating all access to the previous instance.  This is almost
-always a typographical error.  Note that the earlier variable will still exist
-until the end of the scope or until all closure referents to it are
-destroyed.
-
 =item "no" not allowed in expression
 
 (F) The "no" keyword is recognized and executed at compile time, and returns
 no useful value.  See L<perlmod>.
 
+=item "our" variable %s redeclared
+
+(W) You seem to have already declared the same global once before in the
+current lexical scope.
+
 =item "use" not allowed in expression
 
 (F) The "use" keyword is recognized and executed at compile time, and returns
@@ -1284,6 +1289,11 @@
 
 (W) You probably referred to an imported subroutine &FOO as $FOO or some such.
 
+=item Did you mean "local" instead of "our"?
+
+(W) Remember that "our" does not localize the declared global variable.
+You have declared it again in the same lexical scope, which seems superfluous.
+
 =item Did you mean $ or @ instead of %?
 
 (W) You probably said %hash{$key} when you meant $hash{$key} or @hash{@keys}.

==== //depot/perl/t/pragma/strict-vars#9 (text) ====
Index: perl/t/pragma/strict-vars
--- perl/t/pragma/strict-vars.~1~	Tue Jan 25 12:29:52 2000
+++ perl/t/pragma/strict-vars	Tue Jan 25 12:29:52 2000
@@ -339,3 +339,18 @@
 our $foo;
 EXPECT
 "our" variable $foo masks earlier declaration in same scope at - line 7.
+########
+
+# multiple our declarations in same scope, same package, warning
+use strict 'vars';
+use warnings;
+our $foo;
+{
+    our $foo;
+    package Foo;
+    our $foo;
+}
+EXPECT
+"our" variable $foo redeclared at - line 7.
+(Did you mean "local" instead of "our"?)
+Name "Foo::foo" used only once: possible typo at - line 9.
End of Patch.

---

References to:

Gurusamy Sarathy <gsar@ActiveState.com>

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