Remove -foo ambiguity warning

$ ./perl -e 'sub foo{} -foo'
Ambiguous use of -foo resolved as -&foo() at -e line 1.

There is no ambiguity there, since unary minus does not force
its argument to be a bareword; it simply exempts barewords from
strictures.

This warning also makes it harder to use constantly recently added
to POSIX.  To avoid that warning, for negative infinity you have to
write ‘- Inf’ or ‘-+Inf’, because the most natural way of writing it,
‘-Inf’, warns.

See <20140901014232.20757.qmail@lists-nntp.develooper.com> and
related messages.

2 files changed, 6 insertions, 29 deletions

diff --git a/t/lib/warnings/toke b/t/lib/warnings/toke
index 39d3695d59..8c0158a724 100644
--- a/t/lib/warnings/toke
+++ b/t/lib/warnings/toke
@@ -783,15 +783,14 @@ use warnings "ambiguous";
 print for keys %+; # should not warn
 EXPECT
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 sub fred {};
 -fred ;
 sub hank : lvalue {$_}
 --hank; # This should *not* warn [perl #77240]
 EXPECT
-Ambiguous use of -fred resolved as -&fred() at - line 3.
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 $^W = 0 ;
 sub fred {} ;
 -fred ;
@@ -803,19 +802,15 @@ sub fred {} ;
 }
 -fred ;
 EXPECT
-Ambiguous use of -fred resolved as -&fred() at - line 4.
-Ambiguous use of -fred resolved as -&fred() at - line 9.
-Ambiguous use of -fred resolved as -&fred() at - line 11.
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 use utf8;
 use open qw( :utf8 :std );
 sub frèd {};
 -frèd ;
 EXPECT
-Ambiguous use of -frèd resolved as -&frèd() at - line 5.
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 $^W = 0 ;
 use utf8;
 use open qw( :utf8 :std );
@@ -829,19 +824,15 @@ sub frèd {} ;
 }
 -frèd ;
 EXPECT
-Ambiguous use of -frèd resolved as -&frèd() at - line 6.
-Ambiguous use of -frèd resolved as -&frèd() at - line 11.
-Ambiguous use of -frèd resolved as -&frèd() at - line 13.
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 use utf8;
 use open qw( :utf8 :std );
 sub ᒍᒘᒊ {};
 -ᒍᒘᒊ ;
 EXPECT
-Ambiguous use of -ᒍᒘᒊ resolved as -&ᒍᒘᒊ() at - line 5.
 ########
-# toke.c
+# toke.c [This does not warn any more.]
 $^W = 0 ;
 use utf8;
 use open qw( :utf8 :std );
@@ -855,9 +846,6 @@ sub ᒍᒘᒊ {} ;
 }
 -ᒍᒘᒊ ;
 EXPECT
-Ambiguous use of -ᒍᒘᒊ resolved as -&ᒍᒘᒊ() at - line 6.
-Ambiguous use of -ᒍᒘᒊ resolved as -&ᒍᒘᒊ() at - line 11.
-Ambiguous use of -ᒍᒘᒊ resolved as -&ᒍᒘᒊ() at - line 13.
 ########
 # toke.c
 open FOO || time;
diff --git a/toke.c b/toke.c
index 87a34dce92..4d33472cd1 100644
--- a/toke.c
+++ b/toke.c
@@ -6474,10 +6474,6 @@ Perl_yylex(pTHX)
 	  just_a_word: {
 		int pkgname = 0;
 		const char lastchar = (PL_bufptr == PL_oldoldbufptr ? 0 : PL_bufptr[-1]);
-		const char penultchar =
-		    lastchar && PL_bufptr - 2 >= PL_linestart
-			 ? PL_bufptr[-2]
-			 : 0;
 		bool safebw;
 
 
@@ -6686,13 +6682,6 @@ Perl_yylex(pTHX)
 
 		if (cv) {
 		    OP *gvop;
-		    if (lastchar == '-' && penultchar != '-') {
-			const STRLEN l = len ? len : strlen(PL_tokenbuf);
- 			Perl_ck_warner_d(aTHX_ packWARN(WARN_AMBIGUOUS),
-			    "Ambiguous use of -%"UTF8f" resolved as -&%"UTF8f"()",
-			     UTF8fARG(UTF, l, PL_tokenbuf),
-			     UTF8fARG(UTF, l, PL_tokenbuf));
-                    }
 		    /* Check for a constant sub */
 		    if ((sv = cv_const_sv_or_av(cv))) {
 		  its_constant: