feature: Alternative handling of trailing backslashes in macro definitions

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
45/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp
Domain
compilers

Research direction

The issue names no source file or test. Start with the two C++ macro examples and compare their parse-tree endpoints, then read the linked tree-sitter parser documentation and trace how the preproc_arg node is produced. Done means the trailing-backslash case ends at [1, 16], matching the no-trailing-backslash example.

Written by the indexing model from the issue text.

Description

enhancement
Did you check the tree-sitter docs?
Is your feature request related to a problem? Please describe.

Currently, when defining a macro with a trailing backslash \ at the end of the last line, the parse tree extends the preproc_arg end position to the next line.

For example, given:

#define ADD(x, y) \
    ((x) + (y)) \

The parse tree is:

translation_unit [0, 0] - [2, 0]
  preproc_function_def [0, 0] - [2, 0]
    #define [0, 0] - [0, 7]
    name: identifier [0, 8] - [0, 11]
    parameters: preproc_params [0, 11] - [0, 17]
      ( [0, 11] - [0, 12]
      identifier [0, 12] - [0, 13]
      , [0, 13] - [0, 14]
      identifier [0, 15] - [0, 16]
      ) [0, 16] - [0, 17]
    value: preproc_arg [1, 4] - [2, 0]    // Ends at position [2, 0]
Describe the solution you'd like

I was instead wondering if it would be possible to ensure that, in the parse tree, even with a \ at the end of the last line of the macro, the final position of the preproc_arg node matches the following case:

#define ADD(x, y) \
    ((x) + (y))

Where the resulting parse tree is:

translation_unit [0, 0] - [2, 0]
  preproc_function_def [0, 0] - [2, 0]
    #define [0, 0] - [0, 7]
    name: identifier [0, 8] - [0, 11]
    parameters: preproc_params [0, 11] - [0, 17]
      ( [0, 11] - [0, 12]
      identifier [0, 12] - [0, 13]
      , [0, 13] - [0, 14]
      identifier [0, 15] - [0, 16]
      ) [0, 16] - [0, 17]
    value: preproc_arg [1, 4] - [1, 16]    // Ends at position [1, 16]
Dominant language
JavaScript
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