warn about variables in sink context

rakudo · Feb 18, 2013 · 018b73b · 018b73b
1 parent b9ee89a
commit 018b73b
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 2 deletions.
diff --git a/src/Perl6/Actions.pm b/src/Perl6/Actions.pm
@@ -1322,6 +1322,9 @@ class Perl6::Actions is HLL::Actions does STDActions {
                 $past := make_variable($/, [~$/]);
             }
         }
+        if $*IN_DECL eq 'variable' {
+            $past<sink_ok> := 1;
+        }
         make $past;
     }
 

diff --git a/src/Perl6/Optimizer.pm b/src/Perl6/Optimizer.pm
@@ -489,7 +489,16 @@ class Perl6::Optimizer {
 
     # Handles visit a variable node.
     method visit_var($var) {
-        # Nothing to do yet.
+        if  $*VOID_CONTEXT && !$*IN_DECLARATION && $var.name && !$var<sink_ok> {
+            # stuff like Nil is also stored in a QAST::Var, but
+            # we certainly don't want to warn about that one.
+            my str $sigil := nqp::substr($var.name, 0, 1);
+            if $sigil eq '$' || $sigil eq '@' || $sigil eq '%' {
+                self.add_worry($var, "Useless use of variable " ~ $var.name ~ " in sink context");
+                return $NULL;
+            }
+        }
+        $var;
     }
 
     # Checks arguments to see if we're going to be able to do compile
@@ -598,7 +607,7 @@ class Perl6::Optimizer {
                     $node[$i] := self.visit_want($visit);
                 }
                 elsif nqp::istype($visit, QAST::Var) {
-                    self.visit_var($visit);
+                    $node[$i] := self.visit_var($visit);
                 }
                 elsif nqp::istype($visit, QAST::Block) {
                     $node[$i] := self.visit_block($visit);