Add NumberLiteral#zero? (#10248)

Co-authored-by: Johannes Müller <[email protected]>

Author: Sija

spec/compiler/macro/macro_methods_spec.cr

@@ -409,6 +409,14 @@ module Crystal
         assert_macro %({{'a'.ord}}), %(97)
         assert_macro %({{'龍'.ord}}), %(40845)
       end
+
+      it "executes zero?" do
+        assert_macro "{{0.zero?}}", "true"
+        assert_macro "{{1.zero?}}", "false"
+
+        assert_macro "{{0.0.zero?}}", "true"
+        assert_macro "{{0.1.zero?}}", "false"
+      end
     end
 
     describe "string methods" do

src/compiler/crystal/macros.cr

@@ -540,6 +540,10 @@ module Crystal::Macros
 
   # Any number literal.
   class NumberLiteral < ASTNode
+    # Returns `true` if value is 0, `false` otherwise.
+    def zero? : BoolLiteral
+    end
+
     # Compares this node's value to another node's value.
     def <(other : NumberLiteral) : BoolLiteral
     end

src/compiler/crystal/macros/methods.cr

@@ -548,6 +548,8 @@ module Crystal
         interpret_check_args { SymbolLiteral.new(kind.to_s) }
       when "to_number"
         interpret_check_args { MacroId.new(to_number.to_s) }
+      when "zero?"
+        interpret_check_args { BoolLiteral.new(to_number.zero?) }
       else
         super
       end