Handle raise, exit, abort in unreachable code

spec/ameba/rule/lint/unreachable_code_spec.cr

@@ -33,13 +33,46 @@ module Ameba::Rule::Lint
       it "doesn't report if there are returns in if-then-else" do
         s = Source.new %(
           if a > 0
-            return :positivie
+            return :positive
           else
             return :negative
           end
         )
         subject.catch(s).should be_valid
       end
+
+      it "doesn't report if return is used in a block" do
+        s = Source.new %(
+          def foo
+            bar = obj.try do
+              if something
+                a = 1
+              end
+              return nil
+            end
+
+            bar
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+
+      pending "reports if there is unreachable code after if-then-else" do
+        s = Source.new %(
+          def foo
+            if a > 0
+              return :positive
+            else
+              return :negative
+            end
+
+            :unreachable
+          end
+        )
+        subject.catch(s).should_not be_valid
+        issue = s.issues.first
+        issue.location.to_s.should eq ":8:4"
+      end
     end
 
     context "break" do
@@ -98,5 +131,98 @@ module Ameba::Rule::Lint
         subject.catch(s).should be_valid
       end
     end
+
+    context "raise" do
+      it "reports if there is unreachable code after raise" do
+        s = Source.new %(
+          a = 1
+          raise "exception"
+          b = 2
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":3:1"
+      end
+
+      it "doesn't report if raise is in a condition" do
+        s = Source.new %(
+          a = 1
+          raise "exception" if a > 0
+          b = 2
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    context "exit" do
+      it "reports if there is unreachable code after exit without args" do
+        s = Source.new %(
+          a = 1
+          exit
+          b = 2
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":3:1"
+      end
+
+      it "reports if there is unreachable code after exit with exit code" do
+        s = Source.new %(
+          a = 1
+          exit 1
+          b = 2
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":3:1"
+      end
+
+      it "doesn't report if exit is in a condition" do
+        s = Source.new %(
+          a = 1
+          exit if a > 0
+          b = 2
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    context "abort" do
+      it "reports if there is unreachable code after abort with one argument" do
+        s = Source.new %(
+          a = 1
+          abort "abort"
+          b = 2
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":3:1"
+      end
+
+      it "reports if there is unreachable code after abort with two args" do
+        s = Source.new %(
+          a = 1
+          abort "abort", 1
+          b = 2
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":3:1"
+      end
+
+      it "doesn't report if abort is in a condition" do
+        s = Source.new %(
+          a = 1
+          abort "abort" if a > 0
+          b = 2
+        )
+        subject.catch(s).should be_valid
+      end
+    end
   end
 end

src/ameba/ast/visitors/flow_expression_visitor.cr

@@ -4,6 +4,7 @@ module Ameba::AST
   # AST Visitor that traverses all the flow expressions.
   class FlowExpressionVisitor < BaseVisitor
     @node_stack = Array(Crystal::ASTNode).new
+    @flow_expression : FlowExpression?
 
     def initialize(@rule, @source)
       @source.ast.accept self
@@ -14,20 +15,46 @@ module Ameba::AST
     end
 
     def end_visit(node)
-      @node_stack.pop
+      if @flow_expression.nil?
+        @node_stack.pop unless @node_stack.empty?
+      else
+        @flow_expression = nil
+      end
     end
 
     def visit(node : Crystal::ControlExpression)
-      if parent_node = @node_stack.last?
-        flow_expression = FlowExpression.new(node, parent_node)
-        @rule.test @source, node, flow_expression
+      on_flow_expression_start(node)
+
+      true
+    end
+
+    def visit(node : Crystal::Call)
+      if raise?(node) || exit?(node) || abort?(node)
+        on_flow_expression_start(node)
+      else
+        @node_stack.push node
       end
 
       true
     end
 
-    def end_visit(node : Crystal::ControlExpression)
-      #
+    private def on_flow_expression_start(node)
+      if parent_node = @node_stack.last?
+        @flow_expression = FlowExpression.new(node, parent_node)
+        @rule.test @source, node, @flow_expression
+      end
+    end
+
+    private def raise?(node)
+      node.name == "raise" && node.args.size == 1 && node.obj.nil?
+    end
+
+    private def exit?(node)
+      node.name == "exit" && node.args.size <= 1 && node.obj.nil?
+    end
+
+    private def abort?(node)
+      node.name == "abort" && node.args.size <= 2 && node.obj.nil?
     end
   end
 end