refactor binding exceptions

src/Perl6/Actions.pm

@@ -3806,7 +3806,7 @@ class Perl6::Actions is HLL::Actions {
                     $was_lexical := 1;
                 }
                 unless $was_lexical {
-                    $*W.throw($/, ['X', 'Bind', 'WrongLHS']);
+                    $*W.throw($/, ['X', 'Bind', 'Comp']);
                 }
             }
 
@@ -3831,7 +3831,7 @@ class Perl6::Actions is HLL::Actions {
         }
         # XXX Several more cases to do...
         else {
-            $*W.throw($/, ['X', 'Bind', 'WrongLHS']);
+            $*W.throw($/, ['X', 'Bind', 'Comp']);
         }
     }
 

src/core/Any.pm

@@ -1,6 +1,7 @@
 my class MapIter { ... }
 my class Whatever { ... }
 my class Range { ... }
+my class X::Bind::Slice { ... }
 my class X::Bind::ZenSlice { ... }
 
 my class Any {
@@ -125,7 +126,9 @@ my class Any {
 
     proto method postcircumfix:<[ ]>(|$) { * }
     multi method postcircumfix:<[ ]>() { self.list }
-    multi method postcircumfix:<[ ]>(:$BIND!) { die(X::Bind::ZenSlice.new()) }
+    multi method postcircumfix:<[ ]>(:$BIND!) {
+        X::Bind::ZenSlice.new(type => self.WHAT).throw
+    }
     multi method postcircumfix:<[ ]>(\$self: $pos) is rw {
         fail "Cannot use negative index $pos on {$self.WHAT.perl}" if $pos < 0;
         $self.at_pos($pos)
@@ -154,19 +157,19 @@ my class Any {
                    !! { $self[$_] }).eager.Parcel;
     }
     multi method postcircumfix:<[ ]>(Positional $pos, :$BIND!) is rw {
-        die "Cannot bind to an array slice"
+        X::Bind::Slice.new(type => self.WHAT).throw;
     }
     multi method postcircumfix:<[ ]>(\$self: Callable $block) is rw {
         $self[$block(|($self.elems xx $block.count))]
     }
     multi method postcircumfix:<[ ]>(Callable $block, :$BIND!) is rw {
-        die "Cannot bind to a callable array slice"; # WhateverCode?
+        X::Bind::Slice.new(type => self.WHAT).throw;
     }
     multi method postcircumfix:<[ ]>(\$self: Whatever) is rw {
         $self[^$self.elems]
     }
     multi method postcircumfix:<[ ]>(Whatever, :$BIND!) is rw {
-        die "Cannot bind to a whatever array slice"
+        X::Bind::Slice.new(type => self.WHAT).throw;
     }
 
     proto method at_pos(|$) {*}
@@ -194,7 +197,9 @@ my class Any {
     ########
     proto method postcircumfix:<{ }>(|$) { * }
     multi method postcircumfix:<{ }>() { self }
-    multi method postcircumfix:<{ }>(:$BIND!) { die(X::Bind::ZenSlice.new(:what<hash>)) }
+    multi method postcircumfix:<{ }>(:$BIND!) {
+        X::Bind::ZenSlice.new(type => self.WHAT).throw
+    }
     multi method postcircumfix:<{ }>(\$self: $key) is rw {
         $self.at_key($key)
     }
@@ -207,13 +212,13 @@ my class Any {
           !! $key.map({ $self{$_} }).eager.Parcel
     }
     multi method postcircumfix:<{ }>(Positional $key, :$BIND!) is rw {
-        die "Cannot bind to a hash slice"
+        X::Bind::Slice.new(type => self.WHAT).throw
     }
     multi method postcircumfix:<{ }>(\$self: Whatever) is rw {
         $self{$self.keys}
     }
     multi method postcircumfix:<{ }>(Whatever, :$BIND!) is rw {
-        die "Cannot bind to a whatever hash slice"
+        X::Bind::Slice.new(type => self.WHAT).throw
     }
 
     proto method at_key(|$) { * }

src/core/Exception.pm

@@ -419,18 +419,29 @@ my class X::Method::Private::Unqualified does X::Comp {
     }
 }
 
-my class X::Bind::WrongLHS does X::Comp {
-    method message() { 'Cannot use bind operator with this left-hand side' }
+my class X::Bind::Comp does X::Comp {
+    has $.target;
+    method message() {
+        $.target.defined
+            ?? "Cannot bind to $.target"
+            !! 'Cannot use bind operator with this left-hand side'
+    }
 }
 my class X::Bind::NativeType does X::Comp {
     method message() {
         'Cannot bind to a natively typed variable; use assignment instead'
     }
 }
-my class X::Bind::ZenSlice is Exception {
-    has Str $.what = 'array';
-
-    method message() { "Cannot bind to a zen $.what slice." }
+my class X::Bind::Slice is Exception  {
+    has $.type;
+    method message() {
+        "Cannot bind to {$.type.^name} slice";
+    }
+}
+my class X::Bind::ZenSlice is X::Bind::Slice {
+    method message() {
+        "Cannot bind to {$.type.^name} zen slice";
+    }
 }
 
 my class X::Value::Dynamic does X::Comp {