Format multi-line braces blocks using do/end

Fixes crystal-lang#4504

spec/compiler/formatter/formatter_spec.cr

@@ -200,7 +200,7 @@ describe Crystal::Formatter do
   assert_format "foo do   # hello\nend", "foo do # hello\nend"
   assert_format "foo{}", "foo { }"
   assert_format "foo{|x| x}", "foo { |x| x }"
-  assert_format "foo{|x|\n x}", "foo { |x|\n  x\n}"
+  assert_format "foo{|x|\n x}", "foo do |x|\n  x\nend"
   assert_format "foo   &.bar", "foo &.bar"
   assert_format "foo   &.bar( 1 , 2 )", "foo &.bar(1, 2)"
   assert_format "foo.bar  &.baz( 1 , 2 )", "foo.bar &.baz(1, 2)"
@@ -947,6 +947,9 @@ describe Crystal::Formatter do
   assert_format "foo { | a, ( b , c, ), | a + b + c }", "foo { |a, (b, c)| a + b + c }"
   assert_format "foo { | a, ( _ , c ) | a + c }", "foo { |a, (_, c)| a + c }"
 
+  assert_format "foo do |a| 2 end", "foo do |a|\n  2\nend"
+  assert_format "foo { |a|\n  2\n}", "foo do |a|\n  2\nend"
+
   assert_format "def foo\n  {{@type}}\nend"
 
   assert_format "[\n  1, # foo\n  3,\n]"

src/compiler/crystal/tools/formatter.cr

@@ -1243,13 +1243,13 @@ module Crystal
       end
     end
 
-    def format_nested_with_end(node, column = @indent, write_end_line = true)
+    def format_nested_with_end(node, column = @indent, write_end_line = true, force_end = false)
       skip_space(column + 2)
 
       if @token.type == :";"
         if node.is_a?(Nop)
           skip_semicolon_or_space_or_newline
-          check_end
+          check_end unless force_end
           write "; end"
           next_token
           return false
@@ -1259,12 +1259,12 @@ module Crystal
       end
 
       format_nested node, column, write_end_line: write_end_line
-      format_end(column)
+      format_end(column, force_end: force_end)
     end
 
-    def format_end(column)
+    def format_end(column, force_end = false)
       skip_space_or_newline(column + 2, last: true)
-      check_end
+      check_end unless force_end
       write_indent(column)
       write "end"
       next_token
@@ -2480,11 +2480,13 @@ module Crystal
         next_token_skip_space_or_newline
       end
 
-      if @token.keyword?(:do)
+      needs_do_block = node.location.try(&.line_number) != node.end_location.try(&.line_number)
+
+      if @token.keyword?(:do) || (@token.type == :"{" && needs_do_block)
         write " do"
         next_token_skip_space
         body = format_block_args node.args, node
-        format_nested_with_end body
+        format_nested_with_end body, force_end: needs_do_block
       elsif @token.type == :"{"
         write "," if needs_comma
         write " {"