crystal tool format on 'Range'

[willy610]

crystal tool format

Problems when formatting source containing

result_set.rows =(from..to).map { |i| result_set.rows[i] }

Solved by inserting space after the = like

result_set.rows = (from..to).map { |i| result_set.rows[i] }

crystal -v
Crystal 1.7.3 (2023-03-07)

LLVM: 14.0.6
Default target: aarch64-apple-darwin22.3.0

Same problem and solution in VC Code and Extensions

[Blacksmoke16]

What the actual error is, plus trace:

$ ccrystal tool format --show-backtrace test.cr 
Using compiled compiler at /home/george/dev/git/crystal/.build/crystal
Index out of bounds (IndexError)
  from /home/george/dev/git/crystal/src/indexable.cr:803:12 in 'last'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2660:22 in 'visit'
  from /home/george/dev/git/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /home/george/dev/git/crystal/src/compiler/crystal/syntax/visitor.cr:20:7 in 'accept'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:4812:24 in 'indent'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2897:11 in 'format_args_simple'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2859:54 in 'format_args'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2853:5 in 'format_args'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2850:29 in 'format_call_args'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:2736:11 in 'visit'
  from /home/george/dev/git/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:22:7 in 'format'
  from /home/george/dev/git/crystal/src/compiler/crystal/tools/formatter.cr:5:5 in 'format'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:169:7 in 'format'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:137:16 in 'format_source'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:133:7 in 'format_file'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:120:11 in 'format_file_or_directory'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:113:9 in 'format_many'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:102:9 in 'run'
  from /home/george/dev/git/crystal/src/compiler/crystal/command/format.cr:63:5 in 'format'
  from /home/george/dev/git/crystal/src/compiler/crystal/command.cr:174:10 in 'tool'
  from /home/george/dev/git/crystal/src/compiler/crystal/command.cr:114:7 in 'run'
  from /home/george/dev/git/crystal/src/compiler/crystal/command.cr:51:5 in 'run'
  from /home/george/dev/git/crystal/src/compiler/crystal/command.cr:50:3 in 'run'
  from /home/george/dev/git/crystal/src/compiler/crystal.cr:11:1 in '__crystal_main'
  from /home/george/dev/git/crystal/src/crystal/main.cr:115:5 in 'main_user_code'
  from /home/george/dev/git/crystal/src/crystal/main.cr:101:7 in 'main'
  from /home/george/dev/git/crystal/src/crystal/main.cr:127:3 in 'main'
  from /usr/lib/libc.so.6 in '??'
  from /usr/lib/libc.so.6 in '__libc_start_main'
  from /home/george/dev/git/crystal/.build/crystal in '_start'
  from ???

couldn't format './test.cr', please report a bug including the contents of it: https://github.com/crystal-lang/crystal/issues

[hovsater]

I've begun looking into this. The problem can be found here:

crystal/src/compiler/crystal/tools/formatter.cr

Lines 2734 to 2752 in 008d76a

	if assignment
	skip_space
	next_token
	if @token.type.op_lparen?
	write "=("
	slash_is_regex!
	next_token
	format_call_args(node, true, base_indent)
	skip_space_or_newline
	write_token :OP_RPAREN
	else
	write " ="
	skip_space
	accept_assign_value_after_equals node.args.last
	end
	return false
	end

Specifically, if we find a left parentheses, we treat it differently from regular assignment. The problem of course is that range literals starts with the same operand. I was hoping I could use node.has_parentheses? to check whether or not parentheses were used, but unfortunately, it seems like it always returns false.

I'd love to get some input and guidance on how to move forward. 🙂

[straight-shoota]

I think the current formatter behaviour is a bit weird.

foo =(bar) formats to foo=(bar). That's a possible interpretation, but foo = (bar) is probably the more common expectation.
foo= (bar) formats to x.foo = (bar) which seems better to me.

Changing this behaviour keeps the logic pretty sleek:

--- i/src/compiler/crystal/tools/formatter.cr
+++ w/src/compiler/crystal/tools/formatter.cr
@@ -2732,10 +2732,12 @@ module Crystal
       passed_backslash_newline = @token.passed_backslash_newline

       if assignment
+        space_before_assignment = @token.type.space?
         skip_space

         next_token
-        if @token.type.op_lparen?
+        if @token.type.op_lparen? && !space_before_assignment
           write "=("
           slash_is_regex!
           next_token

As a result, only foo=( is considered standard call syntax. If there's any white space around =, the special assignment syntax is used.