Improve useless use warnings of constant in sink

- Use the actual text of numeric literals the user wrote in code
    - ∞ for ∞ / Inf for Inf / un-normalized nums / non-10-base ints
        Fixes R#1696 #1696
- Refer to big ints as "integer" instead of "value", just
    like we do for small ints
- Refer to rationals as "rational" instead of "value"

src/Perl6/Optimizer.nqp

@@ -2000,25 +2000,17 @@ class Perl6::Optimizer {
             my str $warning;
             if $want[1] eq 'Ss' && nqp::istype($want[2], QAST::SVal) {
                 $warning := qq[Useless use of constant string "]
-                         ~ nqp::escape($want[2].value)
+                         ~ nqp::escape($want[2].node // $want[2].value)
                          ~ qq[" in sink context];
             }
             elsif $want[1] eq 'Ii' && nqp::istype($want[2], QAST::IVal) {
                 $warning := qq[Useless use of constant integer ]
-                         ~ ~$want[2].value
+                         ~ ($want[2].node // $want[2].value)
                          ~ qq[ in sink context];
             }
-            elsif $want[1] eq 'Nn' {
-                if nqp::istype($want[2], QAST::NVal) {
-                  $warning := qq[Useless use of constant floating-point number ]
-                    ~ $want[2].value ~ qq[ in sink context];
-                }
-                elsif nqp::istype($want[2], QAST::Op)
-                &&  ($want[2].op eq 'inf' || $want[2].op eq 'nan'
-                  || $want[2].op eq 'neginf') {
-                  $warning := qq[Useless use of constant floating-point number ]
-                    ~ $want[2].node ~ qq[ in sink context];
-                }
+            elsif $want[1] eq 'Nn' && nqp::istype($want[2], QAST::NVal) {
+                $warning := qq[Useless use of constant floating-point number ]
+                  ~ ($want[2].node // $want[2].value) ~ qq[ in sink context];
             }
             if $warning {
                 $warning := $warning ~ ' (use Nil instead to suppress this warning)' if $want.okifnil;
@@ -2262,7 +2254,12 @@ class Perl6::Optimizer {
                             my $suggest := ($visit.okifnil ?? ' (use Nil instead to suppress this warning)' !! '');
                             unless $value eq 'Nil'
                             || $visit.ann('sink-quietly') {
-                                my $warning := qq[Useless use of constant value $value in sink context$suggest];
+                                my $thing :=    nqp::istype($visit.value,
+                                  $!symbols.find_in_setting: 'Int')
+                                ?? 'integer' !! nqp::istype($visit.value,
+                                  $!symbols.find_in_setting: 'Rational')
+                                ?? 'rational' !! 'value';
+                                my $warning := qq[Useless use of constant $thing $value in sink context$suggest];
                                 note($warning) if $!debug;
                                 $!problems.add_worry($visit, $warning)
                             }

src/Perl6/World.nqp

@@ -2713,10 +2713,13 @@ class Perl6::World is HLL::World {
     # Adds a numeric constant value (int or num) to the constants table.
     # Returns PAST to do  the lookup of the constant.
     method add_numeric_constant($/, $type, $value) {
+        my $node := $/;
         if $type eq 'Int' && (try $value.HOW.name($value)) eq 'Int' {
             if nqp::isbig_I($value) {
                 # cannot unbox to int without loss of information
-                return self.add_constant('Int', 'bigint', $value);
+                my $const := self.add_constant('Int', 'bigint', $value);
+                $const.node: $node;
+                return $const;
             }
             # since Int doesn't have any vtables yet (at least while compiling
             # the setting), it is inconvenient to work with, so unbox
@@ -2725,16 +2728,14 @@ class Perl6::World is HLL::World {
         my $const := self.add_constant($type, nqp::lc($type), $value);
         my $past;
         if $type eq 'Int' {
-            $past := QAST::Want.new($const, 'Ii', QAST::IVal.new( :value($value) ) );
+            $past := QAST::Want.new: :$node, $const, 'Ii',
+              QAST::IVal.new: :$node, :$value;
         }
         else {
-            $past := QAST::Want.new: :node($/), $const, 'Nn',
-                       QAST::NVal.new: :node($/), :$value;
+            $past := QAST::Want.new: :$node, $const, 'Nn',
+                       QAST::NVal.new: :$node, :$value;
         }
         $past.returns($const.returns);
-        if $/ {
-            $past.node($/);
-        }
         $past;
     }