From 53bf6bd0766736a2492c40a61683109345f0e418 Mon Sep 17 00:00:00 2001
From: TSUYUSATO Kitsune <make.just.on@gmail.com>
Date: Wed, 16 Aug 2017 23:45:41 +0900
Subject: [PATCH] Fix case-when to pass exhaustiveness check

---
 src/callstack.cr                              |  2 ++
 src/compiler/crystal/semantic/call.cr         |  4 +++
 src/compiler/crystal/semantic/call_error.cr   |  2 ++
 .../crystal/semantic/literal_expander.cr      | 11 ++----
 src/compiler/crystal/semantic/main_visitor.cr | 18 +++++-----
 .../crystal/semantic/semantic_visitor.cr      |  3 +-
 .../crystal/semantic/top_level_visitor.cr     |  4 +--
 src/compiler/crystal/semantic/type_lookup.cr  |  2 ++
 src/compiler/crystal/syntax/exception.cr      |  7 ++--
 src/compiler/crystal/syntax/parser.cr         | 36 +++++++++++++------
 src/compiler/crystal/tools/doc/method.cr      |  2 ++
 src/compiler/crystal/tools/doc/type.cr        | 12 +++----
 src/compiler/crystal/tools/formatter.cr       |  4 +++
 src/compiler/crystal/tools/print_hierarchy.cr |  2 ++
 src/compiler/crystal/types.cr                 | 13 +++++++
 src/http/client.cr                            |  8 ++---
 src/http/common.cr                            | 11 +++---
 src/http/web_socket.cr                        |  2 ++
 src/json/builder.cr                           |  6 ++++
 src/process.cr                                |  8 ++---
 src/socket/addrinfo.cr                        |  2 ++
 src/spec/expectations.cr                      |  2 ++
 src/unicode/unicode.cr                        |  1 +
 src/xml/node.cr                               |  8 ++---
 src/yaml/pull_parser.cr                       |  2 ++
 25 files changed, 111 insertions(+), 61 deletions(-)

diff --git a/src/callstack.cr b/src/callstack.cr
index 28dd04cd7783..fe92ddea9e2d 100644
--- a/src/callstack.cr
+++ b/src/callstack.cr
@@ -214,6 +214,8 @@ struct CallStack
             elsif value.responds_to?(:to_i)
               high_pc = low_pc.as(LibC::SizeT) + value.to_i
             end
+          else
+            # nothing
           end
         end
 
diff --git a/src/compiler/crystal/semantic/call.cr b/src/compiler/crystal/semantic/call.cr
index dc0cf5bfe8d5..cefa022f34e7 100644
--- a/src/compiler/crystal/semantic/call.cr
+++ b/src/compiler/crystal/semantic/call.cr
@@ -40,6 +40,8 @@ class Crystal::Call
     when LibType
       # `LibFoo.call` has a separate logic
       return recalculate_lib_call obj_type
+    else
+      # nothing
     end
 
     # Check if it's call inside LibFoo
@@ -652,6 +654,8 @@ class Crystal::Call
         return result
       when Type::DefInMacroLookup
         return nil
+      else
+        # nothing
       end
     end
   end
diff --git a/src/compiler/crystal/semantic/call_error.cr b/src/compiler/crystal/semantic/call_error.cr
index 0a6d63d50649..06ba98b8ad02 100644
--- a/src/compiler/crystal/semantic/call_error.cr
+++ b/src/compiler/crystal/semantic/call_error.cr
@@ -566,6 +566,8 @@ class Crystal::Call
 
   def check_visibility(match)
     case match.def.visibility
+    when .public?
+      # nothing
     when .private?
       if obj = @obj
         if obj.is_a?(Var) && obj.name == "self" && match.def.name.ends_with?('=')
diff --git a/src/compiler/crystal/semantic/literal_expander.cr b/src/compiler/crystal/semantic/literal_expander.cr
index 71c78c87b757..216acddc3b71 100644
--- a/src/compiler/crystal/semantic/literal_expander.cr
+++ b/src/compiler/crystal/semantic/literal_expander.cr
@@ -616,15 +616,8 @@ module Crystal
         return IsA.new(right_side, cond)
       when Call
         obj = cond.obj
-        case obj
-        when Path
-          if cond.name == "class"
-            return IsA.new(right_side, Metaclass.new(obj.clone).at(obj))
-          end
-        when Generic
-          if cond.name == "class"
-            return IsA.new(right_side, Metaclass.new(obj.clone).at(obj))
-          end
+        if (obj.is_a?(Path) || obj.is_a?(Generic)) && cond.name == "class"
+          return IsA.new(right_side, Metaclass.new(obj.clone).at(obj))
         end
       end
 
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
index e2436547b379..13148b8606d5 100644
--- a/src/compiler/crystal/semantic/main_visitor.cr
+++ b/src/compiler/crystal/semantic/main_visitor.cr
@@ -596,12 +596,12 @@ module Crystal
     def lookup_similar_instance_variable_name(node, owner)
       case owner
       when NonGenericModuleType, GenericClassType, GenericModuleType
-        return nil
-      end
-
-      Levenshtein.find(node.name) do |finder|
-        owner.all_instance_vars.each_key do |name|
-          finder.test(name)
+        nil
+      else
+        Levenshtein.find(node.name) do |finder|
+          owner.all_instance_vars.each_key do |name|
+            finder.test(name)
+          end
         end
       end
     end
@@ -1724,6 +1724,8 @@ module Crystal
         node.raise "can't cast to Reference yet"
       when @program.class_type
         node.raise "can't cast to Class yet"
+      else
+        # nothing
       end
 
       obj_type = node.obj.type?
@@ -2106,9 +2108,9 @@ module Crystal
         end
       when Call
         return get_while_cond_assign_target(node.obj)
+      else
+        nil
       end
-
-      nil
     end
 
     # If we have:
diff --git a/src/compiler/crystal/semantic/semantic_visitor.cr b/src/compiler/crystal/semantic/semantic_visitor.cr
index a7979b979096..2aaeca5ea991 100644
--- a/src/compiler/crystal/semantic/semantic_visitor.cr
+++ b/src/compiler/crystal/semantic/semantic_visitor.cr
@@ -447,8 +447,7 @@ abstract class Crystal::SemanticVisitor < Crystal::Visitor
 
   def class_var_owner(node)
     scope = (@scope || current_type).class_var_owner
-    case scope
-    when Program
+    if scope.is_a?(Program)
       node.raise "can't use class variables at the top level"
     end
 
diff --git a/src/compiler/crystal/semantic/top_level_visitor.cr b/src/compiler/crystal/semantic/top_level_visitor.cr
index a763a4801e6f..0932bfece7b9 100644
--- a/src/compiler/crystal/semantic/top_level_visitor.cr
+++ b/src/compiler/crystal/semantic/top_level_visitor.cr
@@ -595,13 +595,13 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
     method_name = is_flags ? "includes?" : "=="
     body = Call.new(Var.new("self").at(member), method_name, Path.new(member.name).at(member)).at(member)
     a_def = Def.new("#{member.name.underscore}?", body: body).at(member)
-    enum_type.add_def a_def
+    enum_type.add_def a_def, question_method: true
   end
 
   def define_enum_none_question_method(enum_type, node)
     body = Call.new(Call.new(nil, "value").at(node), "==", NumberLiteral.new(0)).at(node)
     a_def = Def.new("none?", body: body).at(node)
-    enum_type.add_def a_def
+    enum_type.add_def a_def, question_method: true
   end
 
   def visit(node : Expressions)
diff --git a/src/compiler/crystal/semantic/type_lookup.cr b/src/compiler/crystal/semantic/type_lookup.cr
index 1fe8627da5af..9deb05eec4f2 100644
--- a/src/compiler/crystal/semantic/type_lookup.cr
+++ b/src/compiler/crystal/semantic/type_lookup.cr
@@ -90,6 +90,8 @@ class Crystal::Type
         return type_var
       when Self
         return lookup(type_var)
+      else
+        # nothing
       end
 
       if @raise
diff --git a/src/compiler/crystal/syntax/exception.cr b/src/compiler/crystal/syntax/exception.cr
index e6991defe64a..3e4e28476dc9 100644
--- a/src/compiler/crystal/syntax/exception.cr
+++ b/src/compiler/crystal/syntax/exception.cr
@@ -64,11 +64,12 @@ module Crystal
     def fetch_source(source)
       case filename = @filename
       when String
-        source = File.read(filename) if File.file?(filename)
+        File.read(filename) if File.file?(filename)
       when VirtualFile
-        source = filename.source
+        filename.source
+      when Nil
+        nil
       end
-      source
     end
 
     def deepest_error_message
diff --git a/src/compiler/crystal/syntax/parser.cr b/src/compiler/crystal/syntax/parser.cr
index f3a2e5d95eb6..d8711fb6148b 100644
--- a/src/compiler/crystal/syntax/parser.cr
+++ b/src/compiler/crystal/syntax/parser.cr
@@ -2933,6 +2933,8 @@ module Crystal
           return MacroIf.new(BoolLiteral.new(true), body).at_end(token_end_location)
         when :else, :elsif, :end
           return nil
+        else
+          # nothing
         end
       end
 
@@ -3548,6 +3550,8 @@ module Crystal
           a_else = parse_expressions
         when :elsif
           a_else = parse_if check_end: false
+        else
+          # nothing
         end
       end
 
@@ -3610,6 +3614,8 @@ module Crystal
       when :nil?
         obj = Var.new("self").at(location)
         return parse_nil?(obj)
+      else
+        # nothing
       end
 
       name = @token.value.to_s
@@ -3639,6 +3645,8 @@ module Crystal
         @calls_initialize = true
       when "previous_def"
         @calls_previous_def = true
+      else
+        # nothing
       end
 
       call_args = preserve_stop_on_do(@stop_on_do) { parse_call_args stop_on_do_after_space: @stop_on_do }
@@ -3984,6 +3992,8 @@ module Crystal
         return nil unless next_comes_colon_space?
       when :yield
         return nil if @stop_on_yield > 0 && !next_comes_colon_space?
+      else
+        # nothing
       end
 
       args = [] of ASTNode
@@ -4126,6 +4136,8 @@ module Crystal
           arg = Splat.new(arg).at(arg.location)
         when :double
           arg = DoubleSplat.new(arg).at(arg.location)
+        else
+          # nothing
         end
 
         arg
@@ -4576,12 +4588,16 @@ module Crystal
           case @token.value
           when :typeof, :self, :sizeof, :instance_sizeof
             return true
+          else
+            # nothing
           end
         when :"::"
           next_token_skip_space
           if @token.type == :CONST
             return true
           end
+        else
+          # nothing
         end
 
         false
@@ -5233,6 +5249,8 @@ module Crystal
           when :protected
             visibility = Visibility::Protected
             next_token_skip_space
+          else
+            # nothing
           end
 
           def_location = @token.location
@@ -5277,21 +5295,16 @@ module Crystal
       node
     end
 
+    END_TOKEN = {:do, :end, :else, :elsif, :when, :rescue, :ensure, :then}
+
     def end_token?
       case @token.type
       when :"}", :"]", :"%}", :EOF
         return true
       end
 
-      if @token.type == :IDENT
-        case @token.value
-        when :do, :end, :else, :elsif, :when, :rescue, :ensure, :then
-          if next_comes_colon_space?
-            return false
-          end
-
-          return true
-        end
+      if @token.type == :IDENT && END_TOKEN.includes?(@token.value)
+        return !next_comes_colon_space?
       end
 
       false
@@ -5374,13 +5387,14 @@ module Crystal
     end
 
     def check_void_expression_keyword
-      case @token.type
-      when :IDENT
+      if @token.type == :IDENT
         case @token.value
         when :break, :next, :return
           unless next_comes_colon_space?
             raise "void value expression", @token, @token.value.to_s.size
           end
+        else
+          # nothing
         end
       end
     end
diff --git a/src/compiler/crystal/tools/doc/method.cr b/src/compiler/crystal/tools/doc/method.cr
index 70b5bf7a238a..b5061e6db2c6 100644
--- a/src/compiler/crystal/tools/doc/method.cr
+++ b/src/compiler/crystal/tools/doc/method.cr
@@ -160,6 +160,8 @@ class Crystal::Doc::Method
     when Crystal::Type
       io << " : "
       @type.type_to_html return_type, io, links: links
+    when Nil
+      # nothing
     end
 
     if free_vars = @def.free_vars
diff --git a/src/compiler/crystal/tools/doc/type.cr b/src/compiler/crystal/tools/doc/type.cr
index 608160f30261..5926afd28af1 100644
--- a/src/compiler/crystal/tools/doc/type.cr
+++ b/src/compiler/crystal/tools/doc/type.cr
@@ -159,10 +159,8 @@ class Crystal::Doc::Type
         defs = [] of Method
         @type.defs.try &.each do |def_name, defs_with_metadata|
           defs_with_metadata.each do |def_with_metadata|
-            case def_with_metadata.def.visibility
-            when .private?, .protected?
-              next
-            end
+            visibility = def_with_metadata.def.visibility
+            next if visibility.private? || visibility.protected?
 
             if @generator.must_include? def_with_metadata.def
               defs << method(def_with_metadata.def, false)
@@ -182,10 +180,8 @@ class Crystal::Doc::Type
       @type.metaclass.defs.try &.each_value do |defs_with_metadata|
         defs_with_metadata.each do |def_with_metadata|
           a_def = def_with_metadata.def
-          case a_def.visibility
-          when .private?, .protected?
-            next
-          end
+          visibility = a_def.visibility
+          next if visibility.private? || visibility.protected?
 
           body = a_def.body
 
diff --git a/src/compiler/crystal/tools/formatter.cr b/src/compiler/crystal/tools/formatter.cr
index 3215f29db0df..d76d97c43ff3 100644
--- a/src/compiler/crystal/tools/formatter.cr
+++ b/src/compiler/crystal/tools/formatter.cr
@@ -2722,6 +2722,8 @@ module Crystal
         else
           clear_object(node.obj)
         end
+      else
+        # nothing
       end
     end
 
@@ -3025,6 +3027,8 @@ module Crystal
 
     def visit(node : VisibilityModifier)
       case node.modifier
+      when .public?
+        # nothing to do because 'public' is default modifier
       when .private?
         write_keyword :private, " "
       when .protected?
diff --git a/src/compiler/crystal/tools/print_hierarchy.cr b/src/compiler/crystal/tools/print_hierarchy.cr
index 15d94f183d11..1050e88aef33 100644
--- a/src/compiler/crystal/tools/print_hierarchy.cr
+++ b/src/compiler/crystal/tools/print_hierarchy.cr
@@ -9,6 +9,8 @@ module Crystal
       HierarchyPrinter.new(program, exp).execute
     when "json"
       JSONHierarchyPrinter.new(program, exp).execute
+    else
+      raise "BUG: invalid format: #{format}"
     end
   end
 
diff --git a/src/compiler/crystal/types.cr b/src/compiler/crystal/types.cr
index 24154e02ddd5..2fd1de6b26cf 100644
--- a/src/compiler/crystal/types.cr
+++ b/src/compiler/crystal/types.cr
@@ -2403,10 +2403,13 @@ module Crystal
     getter base_type : IntegerType
     getter? flags : Bool
 
+    getter question_methods
+
     def initialize(program, namespace, name, @base_type, flags)
       super(program, namespace, name)
 
       @flags = !!flags
+      @question_methods = Set(String).new
 
       add_def Def.new("value", [] of Arg, Primitive.new("enum_value", @base_type))
       metaclass.as(ModuleType).add_def Def.new("new", [Arg.new("value", type: @base_type)], Primitive.new("enum_new", self))
@@ -2422,6 +2425,16 @@ module Crystal
       const
     end
 
+    def add_def(a_def, question_method = false)
+      if question_method
+        question_methods.add(a_def.name)
+      else
+        question_methods.delete(a_def.name)
+      end
+
+      super(a_def)
+    end
+
     def has_attribute?(name)
       return true if flags? && name == "Flags"
       false
diff --git a/src/http/client.cr b/src/http/client.cr
index abb178956fe8..b18425cac6f9 100644
--- a/src/http/client.cr
+++ b/src/http/client.cr
@@ -117,12 +117,12 @@ class HTTP::Client
   {% else %}
     def initialize(@host : String, port = nil, tls : Bool | OpenSSL::SSL::Context::Client = false)
       @tls = case tls
-             when true
-               OpenSSL::SSL::Context::Client.new
+             when Bool
+               if tls
+                 OpenSSL::SSL::Context::Client.new
+               end
              when OpenSSL::SSL::Context::Client
                tls
-             when false
-               nil
              end
 
       @port = (port || (@tls ? 443 : 80)).to_i
diff --git a/src/http/common.cr b/src/http/common.cr
index c369fb65be85..0edb21f1c106 100644
--- a/src/http/common.cr
+++ b/src/http/common.cr
@@ -48,6 +48,8 @@ module HTTP
               body = Gzip::Reader.new(body, sync_close: true)
             when "deflate"
               body = Flate::Reader.new(body, sync_close: true)
+            else
+              # ignore unsupported encoding
             end
           {% end %}
         end
@@ -176,14 +178,11 @@ module HTTP
       return true
     when "close", "upgrade"
       return false
-    end
-
-    case message.version
-    when "HTTP/1.0"
-      false
     else
-      true
+      # nothing
     end
+
+    message.version != "HTTP/1.0"
   end
 
   record ComputedContentTypeHeader,
diff --git a/src/http/web_socket.cr b/src/http/web_socket.cr
index 3e1d95d4fd6f..1c164af73753 100644
--- a/src/http/web_socket.cr
+++ b/src/http/web_socket.cr
@@ -141,6 +141,8 @@ class HTTP::WebSocket
           @current_message.clear
           break
         end
+      when Protocol::Opcode::CONTINUATION
+        raise "BUG: CONTINUATION does not appear here"
       end
     end
   end
diff --git a/src/json/builder.cr b/src/json/builder.cr
index 64618a37a237..432db1547694 100644
--- a/src/json/builder.cr
+++ b/src/json/builder.cr
@@ -41,6 +41,8 @@ class JSON::Builder
       raise JSON::Error.new("Empty JSON")
     when DocumentStartState
       raise JSON::Error.new("Empty JSON")
+    when DocumentEndState
+      # nothing
     when ArrayState
       raise JSON::Error.new("Unterminated JSON array")
     when ObjectState
@@ -267,6 +269,8 @@ class JSON::Builder
     case state = @state.last
     when StartState
       raise JSON::Error.new("Write before start_document")
+    when DocumentStartState
+      # nothing
     when DocumentEndState
       raise JSON::Error.new("Write past end_document and before start_document")
     when ArrayState
@@ -290,6 +294,8 @@ class JSON::Builder
     when ObjectState
       colon if state.name
       @state[-1] = ObjectState.new(empty: false, name: !state.name)
+    else
+      # nothing
     end
   end
 
diff --git a/src/process.cr b/src/process.cr
index ebe70c5536c6..e118a3ba4930 100644
--- a/src/process.cr
+++ b/src/process.cr
@@ -118,15 +118,15 @@ class Process
   # *run_hooks* should ALWAYS be `true` unless `exec` is used immediately after fork.
   # Channels, `IO` and other will not work reliably if *run_hooks* is `false`.
   protected def self.fork_internal(run_hooks : Bool = true)
-    pid = LibC.fork
-    case pid
+    case pid = LibC.fork
     when 0
-      pid = nil
       Process.after_fork_child_callbacks.each(&.call) if run_hooks
+      nil
     when -1
       raise Errno.new("fork")
+    else
+      pid
     end
-    pid
   end
 
   # The standard `IO` configuration of a process:
diff --git a/src/socket/addrinfo.cr b/src/socket/addrinfo.cr
index 9b4327515b22..3c36d359cbc9 100644
--- a/src/socket/addrinfo.cr
+++ b/src/socket/addrinfo.cr
@@ -159,6 +159,8 @@ class Socket
         addrinfo.value.ai_addr.as(LibC::SockaddrIn6*).copy_to(pointerof(@addr).as(LibC::SockaddrIn6*), 1)
       when Family::INET
         addrinfo.value.ai_addr.as(LibC::SockaddrIn*).copy_to(pointerof(@addr).as(LibC::SockaddrIn*), 1)
+      else
+        # nothing
       end
     end
 
diff --git a/src/spec/expectations.cr b/src/spec/expectations.cr
index 2d785b71bcb0..ad5cede20b66 100644
--- a/src/spec/expectations.cr
+++ b/src/spec/expectations.cr
@@ -272,6 +272,8 @@ module Spec
             backtrace = %ex.backtrace.map { |f| "  # #{f}" }.join "\n"
             fail "Expected {{klass.id}} with #{ %msg.inspect }, got #<#{ %ex.class }: #{ %ex_to_s }> with backtrace:\n#{backtrace}", {{file}}, {{line}}
           end
+        else
+          # skip
         end
 
         %ex
diff --git a/src/unicode/unicode.cr b/src/unicode/unicode.cr
index ab8c7fd52f70..2a40424904e1 100644
--- a/src/unicode/unicode.cr
+++ b/src/unicode/unicode.cr
@@ -148,6 +148,7 @@ module Unicode
       case char
       when 'I'; return 'ı'
       when 'İ'; return 'i'
+      else # nothing
       end
     end
     nil
diff --git a/src/xml/node.cr b/src/xml/node.cr
index 3c23a238036f..219f1f2d8420 100644
--- a/src/xml/node.cr
+++ b/src/xml/node.cr
@@ -282,11 +282,11 @@ struct XML::Node
   def namespace
     case type
     when Type::DOCUMENT_NODE, Type::ATTRIBUTE_DECL, Type::DTD_NODE, Type::ELEMENT_DECL
-      return nil
+      nil
+    else
+      ns = @node.value.ns
+      ns ? Namespace.new(document, ns) : nil
     end
-
-    ns = @node.value.ns
-    ns ? Namespace.new(document, ns) : nil
   end
 
   # Returns namespaces in scope for self – those defined on self element
diff --git a/src/yaml/pull_parser.cr b/src/yaml/pull_parser.cr
index 8f0a7fb94500..02fba3046a56 100644
--- a/src/yaml/pull_parser.cr
+++ b/src/yaml/pull_parser.cr
@@ -239,6 +239,8 @@ class YAML::PullParser
         skip
       end
       read_next
+    else
+      # not skip this event
     end
   end