Detect correct missing open brace

[jkeiser]

Right now, this will report closing { without open } on the end brace, which makes it really hard to find out where the actual error was. Indentation makes it pretty clear, so we should modify the rules to make it better:

MyClass: {
    Function1: {
        if (:x == :y) # this is the line with the missing {
           10
        } # error SHOULD be reported here
    }
    Function2: {
        :x + :y
    }
} # error is reported here

[jkeiser]

One way to do this would be to require close braces to be on the same block level as the opening brace. However, we allow expressions to be continued on indented lines in order to support things like this:

:x = if y > 0 {
        1000 / y
     } else { # this close brace is not on the same indent level as the corresponding opening brace
         0
     }

[jkeiser]

A rule that might work, however, would be "a close operator MUST close something from either the current line or the last open line." That would mean:

# this is OK
MyFunction: {
    if y > 0 {
        1000/y
    } else {
        0
    }
}

# this is OK
MyFunction: {
    x = if y > 0 {
           1000 / y
       } else {
           0
       }
}

# this is an error
MyFunction: {
    # we will guess the open brace needs to be here
    y = :y + 1
    if y > 0
        1000/y
    } else { # error: this close brace causes both "if y > 0 ..." and its parent, "MyFunction: {", to be closed.         
        0
    }
}

# this is an error
MyFunction: {
    y = :y + 1
    if y > 0 {
        # we will estimate the close brace here
        1000/y
        } else { # error: this close brace causes both "1000/y" and its parent, "if y > 0 {", to be closed.
            0
        }
}

# this is ok :/
MyFunction: {
    y = :y + 1
    if y > 0 {
            1000/y
        } else {
            0
        }
}

[jkeiser]

This rule could be expanded reasonably to include other operators:

x = 10 + 20
  + 30 + 40
      + 50 + 60; y = 10 # semicolon would be an error

x = 10 * 20
  * 30 * 40 *
    50 + 60 # error: + closes the * two lines above