crystal-lang · Dec 12, 2016 · Dec 12, 2016 · Dec 12, 2016 · Dec 12, 2016
diff --git a/spec/compiler/semantic/instance_var_spec.cr b/spec/compiler/semantic/instance_var_spec.cr
@@ -4560,4 +4560,22 @@ describe "Semantic: instance var" do
       Foo.new.a
       )) { bool }
   end
+
+  it "doesn't consider var as nilable if conditionally assigned inside initialize, but has initializer (#3669)" do
+    assert_type(%(
+      class Foo
+        @x = 0
+
+        def initialize
+          @x = 1 if 1 == 2
+        end
+
+        def x
+          @x
+        end
+      end
+
+      Foo.new.x
+      )) { int32 }
+  end
 end
diff --git a/spec/std/io/argf_spec.cr b/spec/std/io/argf_spec.cr
@@ -37,4 +37,38 @@ describe IO::ARGF do
     str = argf.gets(5)
     str.should eq("12345")
   end
+
+  describe "gets" do
+    it "reads from STDIN if ARGV isn't specified" do
+      argv = [] of String
+      stdin = IO::Memory.new("hello\nworld\n")
+
+      argf = IO::ARGF.new argv, stdin
+      argf.gets.should eq("hello\n")
+      argf.gets.should eq("world\n")
+      argf.gets.should be_nil
+    end
+
+    it "reads from ARGV if specified" do
+      path1 = "#{__DIR__}/../data/argf_test_file_1.txt"
+      path2 = "#{__DIR__}/../data/argf_test_file_2.txt"
+      stdin = IO::Memory.new("")
+      argv = [path1, path2]
+
+      argf = IO::ARGF.new argv, stdin
+      argv.should eq([path1, path2])
+
+      argf.gets.should eq("12345\n")
+      argv.should eq([path2])
+
+      argf.gets.should eq("67890\n")
+      argv.empty?.should be_true
+
+      argf.gets.should be_nil
+
+      argv << path1
+      str = argf.gets
+      str.should eq("12345\n")
+    end
+  end
 end
diff --git a/spec/std/io/sized_spec.cr b/spec/std/io/sized_spec.cr
@@ -90,4 +90,13 @@ describe "IO::Sized" do
     sized.read_byte.should eq('c'.ord)
     sized.read_byte.should be_nil
   end
+
+  it "gets" do
+    io = IO::Memory.new "foo\nbar\nbaz"
+    sized = IO::Sized.new(io, read_size: 9)
+    sized.gets.should eq("foo\n")
+    sized.gets.should eq("bar\n")
+    sized.gets.should eq("b")
+    sized.gets.should be_nil
+  end
 end
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
@@ -773,12 +773,16 @@ module Crystal
       if @is_initialize
         var_name = target.name
 
-        meta_var = (@meta_vars[var_name] ||= new_meta_var(var_name))
-        meta_var.bind_to value
-        meta_var.assigned_to = true
+        # Don't track instance variables nilabilty (for example, if they were
+        # just assigned inside a branch) if they have an initializer
+        unless scope.has_instance_var_initializer?(var_name)
+          meta_var = (@meta_vars[var_name] ||= new_meta_var(var_name))
+          meta_var.bind_to value
+          meta_var.assigned_to = true
 
-        simple_var = MetaVar.new(var_name)
-        simple_var.bind_to(target)
+          simple_var = MetaVar.new(var_name)
+          simple_var.bind_to(target)
+        end
 
         used_ivars_in_calls_in_initialize = @used_ivars_in_calls_in_initialize
         if (found_self = @found_self_in_initialize_call) || (used_ivars_node = used_ivars_in_calls_in_initialize.try(&.[var_name]?)) || (@block_nest > 0 && !@vars.has_key?(var_name))
@@ -791,9 +795,11 @@ module Crystal
           ivar.bind_to program.nil_var
         end
 
-        @vars[var_name] = simple_var
+        if simple_var
+          @vars[var_name] = simple_var
 
-        check_exception_handler_vars var_name, value
+          check_exception_handler_vars var_name, value
+        end
       end
     end
 

diff --git a/src/http/content.cr b/src/http/content.cr
@@ -34,6 +34,12 @@ module HTTP
       @io.read_byte
     end
 
+    def gets(delimiter : Char, limit : Int) : String?
+      return super if @encoding
+
+      @io.gets(delimiter, limit)
+    end
+
     def write(slice : Slice(UInt8))
       raise IO::Error.new "Can't write to UnknownLengthContent"
     end

diff --git a/src/io/argf.cr b/src/io/argf.cr
@@ -31,6 +31,33 @@ class IO::ARGF
     read_count
   end
 
+  # :nodoc:
+  def gets(delimiter : Char, limit : Int) : String?
+    return super if @encoding
+
+    first_initialize unless @initialized
+
+    if current_io = @current_io
+      string = current_io.gets(delimiter, limit)
+      if !string && !@read_from_stdin
+        current_io.close
+        if @argv.empty?
+          @current_io = nil
+        else
+          read_next_argv
+          string = gets(delimiter, limit)
+        end
+      end
+    elsif !@read_from_stdin && !@argv.empty?
+      read_next_argv
+      string = gets(delimiter, limit)
+    else
+      string = nil
+    end
+
+    string
+  end
+
   def write(slice : Slice(UInt8))
     raise IO::Error.new "can't write to ARGF"
   end

diff --git a/src/io/sized.cr b/src/io/sized.cr
@@ -49,6 +49,17 @@ module IO
       end
     end
 
+    def gets(delimiter : Char, limit : Int) : String?
+      check_open
+
+      return super if @encoding
+      return nil if @read_remaining == 0
+
+      string = @io.gets(delimiter, Math.min(limit, @read_remaining))
+      @read_remaining -= string.bytesize if string
+      string
+    end
+
     def write(slice : Slice(UInt8))
       raise IO::Error.new "Can't write to IO::Sized"
     end