Add return type restrictions to I/O methods (#10580)

src/compress/deflate/reader.cr

@@ -52,12 +52,12 @@ class Compress::Deflate::Reader < IO
   end
 
   # Always raises `IO::Error` because this is a read-only `IO`.
-  def unbuffered_write(slice : Bytes)
+  def unbuffered_write(slice : Bytes) : NoReturn
     raise IO::Error.new "Can't write to Compress::Deflate::Reader"
   end
 
   # See `IO#read`.
-  def unbuffered_read(slice : Bytes)
+  def unbuffered_read(slice : Bytes) : Int32
     check_open
 
     return 0 if slice.empty?
@@ -125,7 +125,7 @@ class Compress::Deflate::Reader < IO
     end
   end
 
-  def unbuffered_flush
+  def unbuffered_flush : NoReturn
     raise IO::Error.new "Can't flush Compress::Deflate::Reader"
   end
 

src/compress/deflate/writer.cr

@@ -38,7 +38,7 @@ class Compress::Deflate::Writer < IO
   end
 
   # Always raises `IO::Error` because this is a write-only `IO`.
-  def read(slice : Bytes)
+  def read(slice : Bytes) : NoReturn
     raise "Can't read from Flate::Writer"
   end
 
@@ -77,7 +77,7 @@ class Compress::Deflate::Writer < IO
   end
 
   # Returns `true` if this IO is closed.
-  def closed?
+  def closed? : Bool
     @closed
   end
 

src/compress/gzip/reader.cr

@@ -78,7 +78,7 @@ class Compress::Gzip::Reader < IO
   end
 
   # See `IO#read`.
-  def unbuffered_read(slice : Bytes)
+  def unbuffered_read(slice : Bytes) : Int32
     check_open
 
     return 0 if slice.empty?
@@ -133,7 +133,7 @@ class Compress::Gzip::Reader < IO
     raise IO::Error.new("Can't write to Compress::Gzip::Reader")
   end
 
-  def unbuffered_flush
+  def unbuffered_flush : NoReturn
     raise IO::Error.new "Can't flush Compress::Gzip::Reader"
   end
 

src/compress/gzip/writer.cr

@@ -63,7 +63,7 @@ class Compress::Gzip::Writer < IO
   end
 
   # Always raises `IO::Error` because this is a write-only `IO`.
-  def read(slice : Bytes)
+  def read(slice : Bytes) : NoReturn
     raise IO::Error.new("Can't read from Gzip::Writer")
   end
 

src/compress/zip/checksum_reader.cr

@@ -8,7 +8,7 @@ module Compress::Zip
     def initialize(@io : IO, @filename : String, verify @expected_crc32 : UInt32? = nil)
     end
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : Int32
       read_bytes = @io.read(slice)
       if read_bytes == 0
         if (expected_crc32 = @expected_crc32) && crc32 != expected_crc32
@@ -20,7 +20,7 @@ module Compress::Zip
       read_bytes
     end
 
-    def peek
+    def peek : Bytes?
       @io.peek
     end
 

src/compress/zip/checksum_writer.cr

@@ -9,7 +9,7 @@ module Compress::Zip
     def initialize(@compute_crc32 = false)
     end
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : NoReturn
       raise IO::Error.new "Can't read from Zip::Writer entry"
     end
 

src/compress/zlib/reader.cr

@@ -58,7 +58,7 @@ class Compress::Zlib::Reader < IO
   end
 
   # See `IO#read`.
-  def unbuffered_read(slice : Bytes)
+  def unbuffered_read(slice : Bytes) : Int32
     check_open
 
     return 0 if slice.empty?
@@ -81,11 +81,11 @@ class Compress::Zlib::Reader < IO
   end
 
   # Always raises `IO::Error` because this is a read-only `IO`.
-  def unbuffered_write(slice : Bytes)
+  def unbuffered_write(slice : Bytes) : NoReturn
     raise IO::Error.new "Can't write to Compress::Zlib::Reader"
   end
 
-  def unbuffered_flush
+  def unbuffered_flush : NoReturn
     raise IO::Error.new "Can't flush Compress::Zlib::Reader"
   end
 

src/compress/zlib/writer.cr

@@ -39,7 +39,7 @@ class Compress::Zlib::Writer < IO
   end
 
   # Always raises `IO::Error` because this is a write-only `IO`.
-  def read(slice : Bytes)
+  def read(slice : Bytes) : NoReturn
     raise IO::Error.new("Can't read from Gzip::Writer")
   end
 

src/digest/io_digest.cr

@@ -30,7 +30,7 @@ class IO::Digest < IO
   def initialize(@io : IO, @digest_algorithm : ::Digest, @mode = DigestMode::Read)
   end
 
-  def read(slice : Bytes)
+  def read(slice : Bytes) : Int32
     read_bytes = io.read(slice)
     if @mode.read?
       digest_algorithm.update(slice[0, read_bytes])

src/file/preader.cr

@@ -26,11 +26,11 @@ class File::PReader < IO
     bytes_read
   end
 
-  def unbuffered_write(slice : Bytes)
+  def unbuffered_write(slice : Bytes) : NoReturn
     raise IO::Error.new("Can't write to read-only IO")
   end
 
-  def unbuffered_flush
+  def unbuffered_flush : NoReturn
     raise IO::Error.new("Can't flush read-only IO")
   end
 

src/http/content.cr

@@ -26,27 +26,27 @@ module HTTP
   class FixedLengthContent < IO::Sized
     include Content
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : Int32
       ensure_send_continue
       super
     end
 
-    def read_byte
+    def read_byte : UInt8?
       ensure_send_continue
       super
     end
 
-    def peek
+    def peek : Bytes?
       ensure_send_continue
       super
     end
 
-    def skip(bytes_count)
+    def skip(bytes_count) : Nil
       ensure_send_continue
       super
     end
 
-    def write(slice : Bytes)
+    def write(slice : Bytes) : NoReturn
       raise IO::Error.new "Can't write to FixedLengthContent"
     end
   end
@@ -58,22 +58,22 @@ module HTTP
     def initialize(@io : IO)
     end
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : Int32
       ensure_send_continue
       @io.read(slice)
     end
 
-    def read_byte
+    def read_byte : UInt8?
       ensure_send_continue
       @io.read_byte
     end
 
-    def peek
+    def peek : Bytes?
       ensure_send_continue
       @io.peek
     end
 
-    def skip(bytes_count)
+    def skip(bytes_count) : Int32?
       ensure_send_continue
       @io.skip(bytes_count)
     end
@@ -112,7 +112,7 @@ module HTTP
       @received_final_chunk = false
     end
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : Int32
       ensure_send_continue
       count = slice.size
       return 0 if count == 0
@@ -134,7 +134,7 @@ module HTTP
       bytes_read
     end
 
-    def read_byte
+    def read_byte : UInt8?
       ensure_send_continue
       next_chunk
       return super if @received_final_chunk
@@ -148,7 +148,7 @@ module HTTP
       end
     end
 
-    def peek
+    def peek : Bytes?
       ensure_send_continue
       next_chunk
       return Bytes.empty if @received_final_chunk
@@ -164,7 +164,7 @@ module HTTP
       peek
     end
 
-    def skip(bytes_count)
+    def skip(bytes_count) : Int32?
       ensure_send_continue
       if bytes_count <= @chunk_remaining
         @io.skip(bytes_count)
@@ -233,7 +233,7 @@ module HTTP
       raise IO::Error.new "Can't write to ChunkedContent"
     end
 
-    def closed?
+    def closed? : Bool
       @received_final_chunk || super
     end
   end

src/http/server/response.cr

@@ -92,7 +92,7 @@ class HTTP::Server
     end
 
     # :nodoc:
-    def read(slice : Bytes)
+    def read(slice : Bytes) : NoReturn
       raise "Can't read from HTTP::Server::Response"
     end
 
@@ -117,7 +117,7 @@ class HTTP::Server
     end
 
     # Returns `true` if this response has been closed.
-    def closed?
+    def closed? : Bool
       @output.closed?
     end
 

src/http/web_socket/protocol.cr

@@ -70,7 +70,7 @@ class HTTP::WebSocket::Protocol
       end
     end
 
-    def read(slice : Bytes)
+    def read(slice : Bytes) : NoReturn
       raise "This IO is write-only"
     end
 

src/io.cr

@@ -110,7 +110,7 @@ abstract class IO
   # Returns `true` if this `IO` is closed.
   #
   # `IO` defines returns `false`, but including types may override.
-  def closed?
+  def closed? : Bool
     false
   end
 
@@ -389,7 +389,7 @@ abstract class IO
   #
   # "你".bytes # => [228, 189, 160]
   # ```
-  def read_utf8_byte
+  def read_utf8_byte : UInt8?
     if decoder = decoder()
       decoder.read_byte(self)
     else
@@ -464,7 +464,7 @@ abstract class IO
   end
 
   # Writes a slice of UTF-8 encoded bytes to this `IO`, using the current encoding.
-  def write_utf8(slice : Bytes)
+  def write_utf8(slice : Bytes) : Nil
     if encoder = encoder()
       encoder.write(self, slice)
     else
@@ -500,7 +500,7 @@ abstract class IO
   # slice                # => Bytes[49, 50, 51, 52, 53]
   # io.read_fully(slice) # raises IO::EOFError
   # ```
-  def read_fully(slice : Bytes)
+  def read_fully(slice : Bytes) : Int32
     read_fully?(slice) || raise(EOFError.new)
   end
 
@@ -515,7 +515,7 @@ abstract class IO
   # slice                 # => Bytes[49, 50, 51, 52, 53]
   # io.read_fully?(slice) # => nil
   # ```
-  def read_fully?(slice : Bytes)
+  def read_fully?(slice : Bytes) : Int32?
     count = slice.size
     while slice.size > 0
       read_bytes = read slice
@@ -839,7 +839,7 @@ abstract class IO
   # io.write_byte 97_u8
   # io.to_s # => "a"
   # ```
-  def write_byte(byte : UInt8)
+  def write_byte(byte : UInt8) : Nil
     x = byte
     write Slice.new(pointerof(x), 1)
   end
@@ -858,7 +858,7 @@ abstract class IO
   # io.rewind
   # io.gets(4) # => "\u{4}\u{3}\u{2}\u{1}"
   # ```
-  def write_bytes(object, format : IO::ByteFormat = IO::ByteFormat::SystemEndian)
+  def write_bytes(object, format : IO::ByteFormat = IO::ByteFormat::SystemEndian) : Nil
     object.to_io(self, format)
   end
 
@@ -1031,7 +1031,7 @@ abstract class IO
   end
 
   # :nodoc:
-  def has_non_utf8_encoding?
+  def has_non_utf8_encoding? : Bool
     !!@encoding
   end
 
@@ -1157,7 +1157,7 @@ abstract class IO
   # stream2 = IO::Memory.new("123")
   # IO.same_content?(stream1, stream2) # => true
   # ```
-  def self.same_content?(stream1 : IO, stream2 : IO)
+  def self.same_content?(stream1 : IO, stream2 : IO) : Bool
     buf1 = uninitialized UInt8[1024]
     buf2 = uninitialized UInt8[1024]
 

src/io/argf.cr

@@ -10,7 +10,7 @@ class IO::ARGF < IO
     @read_from_stdin = false
   end
 
-  def read(slice : Bytes)
+  def read(slice : Bytes) : Int32
     first_initialize unless @initialized
 
     if current_io = @current_io
@@ -29,7 +29,7 @@ class IO::ARGF < IO
   end
 
   # :nodoc:
-  def peek
+  def peek : Bytes?
     first_initialize unless @initialized
 
     if current_io = @current_io
@@ -57,7 +57,7 @@ class IO::ARGF < IO
     raise IO::Error.new "Can't write to ARGF"
   end
 
-  def path
+  def path : String
     @path || @argv.first? || "-"
   end