Whitespace issue with if conditions

[ajeetdsouza]

Askama seems to be including whitespace from inside an if condition even when the condition is not fulfilled. Here is my template file:

{%- if some_condition -%}
# WARNING

{% endif -%}

# FILE START

What I expected is:

• When some_condition is true:

  # WARNING
  
  # FILE START
  

• When some_condition is false:

  # FILE START
  

What I got is:

• When some_condition is true: same as expected output

• When some_condition is false (notice the blank lines before FILE START):

  
  
  # FILE START
  

Is this a bug? If not, is there a way to get the behaviour I described?

[djc]

It sure sounds like a bug! Let me look at some code.

[djc]

So the code generation for if statements is here:

https://github.com/djc/askama/blob/main/askama_shared/src/generator.rs#L502

I don't immediately see anything obviously wrong. Maybe you can contribute a test case and/or use the debugging facility (add print = "code" to your template attribute) to look at the generated code and see what's going on?

[ajeetdsouza]

@djc I've added the test. Using print = "code" makes the bug more apparent - it's adding the newlines outside the if condition rather than inside:

fn render_into(&self, writer: &mut dyn ::std::fmt::Write) -> ::askama::Result<()> {
    include_bytes !
("/home/ajeetdsouza/ws/askama/testing/templates/cond-whitespace.txt") ;
    if self.show_preamble {
        writer.write_str("preamble")?;
    }
    writer.write_str("\n\nintroduction\n\nconclusion")?;
    Ok(())
}