AST::ImplicitReturnVisitor macro expression and control support

spec/ameba/rule/lint/unused_literal_spec.cr

@@ -290,6 +290,26 @@ module Ameba::Rule::Lint
         CRYSTAL
     end
 
+    it "fails if unused literals in macro expressions" do
+      expect_issue subject, <<-CRYSTAL
+        {{ "hello world" }}
+        {% "hello world" %}
+         # ^^^^^^^^^^^^^ error: Literal value is not used
+
+        {%
+          if var == 2
+            "2"
+          # ^^^ error: Literal value is not used
+          end
+        %}
+
+        macro name(foo)
+          {% "bar" %}
+           # ^^^^^ error: Literal value is not used
+        end
+        CRYSTAL
+    end
+
     # Locations for Regex literals were added in Crystal v1.15.0
     {% if compare_versions(Crystal::VERSION, "1.15.0") >= 0 %}
       it "fails if a regex literal is unused" do

src/ameba/ast/visitors/implicit_return_visitor.cr

@@ -140,6 +140,19 @@ module Ameba::AST
       false
     end
 
+    def visit(node : Crystal::Macro) : Bool
+      @rule.test(@source, node, @stack.positive?)
+
+      incr_stack do
+        node.args.each &.accept(self)
+        node.double_splat.try &.accept(self)
+        node.block_arg.try &.accept(self)
+        node.body.accept(self)
+      end
+
+      false
+    end
+
     def visit(node : Crystal::ClassDef | Crystal::ModuleDef) : Bool
       @rule.test(@source, node, @stack.positive?)
 
@@ -313,13 +326,43 @@ module Ameba::AST
       false
     end
 
-    def visit(node : Crystal::Generic | Crystal::Path | Crystal::Union) : Bool
+    def visit(node : Crystal::MacroExpression) : Bool
+      @rule.test(@source, node, @stack.positive?)
+
+      if node.output?
+        incr_stack { node.exp.accept(self) }
+      else
+        node.exp.accept(self)
+      end
+
+      false
+    end
+
+    def visit(node : Crystal::MacroIf) : Bool
       @rule.test(@source, node, @stack.positive?)
 
+      incr_stack { node.cond.accept(self) }
+      node.then.accept(self)
+      node.else.accept(self)
+
       false
     end
 
-    def visit(node : Crystal::Macro | Crystal::MacroIf | Crystal::MacroFor) : Bool
+    def visit(node : Crystal::MacroFor) : Bool
+      @rule.test(@source, node, @stack.positive?)
+
+      node.body.accept(self)
+
+      false
+    end
+
+    def visit(node : Crystal::MacroVar)
+      @rule.test(@source, node, @stack.positive?)
+
+      false
+    end
+
+    def visit(node : Crystal::Generic | Crystal::Path | Crystal::Union) : Bool
       @rule.test(@source, node, @stack.positive?)
 
       false