f90-ts-mode is a major mode for editing Fortran 90/2003 (and newer) source
files, based on Emacs's built-in tree-sitter support (requires Emacs 30+)

Features:
  - Syntax highlighting
  - Indentation
  - Alignment for multiline statements where applicable
  - Smart end completion
  - Breaking and joining continued lines
  - (Un)commenting regions with configurable prefixes
  - OpenMP and preprocessor directives
  - Region selection based on tree-sitter nodes
  - Xref (buffer local)
  - Imenu
  - Fortran menu and transient keybindings

Features can be found by the fortran menu or a transient popup bound
to the key C-c C-f.

Installation requires the tree-sitter Fortran grammar, which can be found at
  https://github.com/stadelmanma/tree-sitter-fortran

Basic setup with use-package:

  (use-package f90-ts-mode
    :mode ("\\.f90\\'" . f90-ts-mode))

See the README and MANUAL at https://github.com/mscfd/emacs-f90-ts-mode
for full documentation on options, keybindings, etc.

Bugs and features:
  https://github.com/mscfd/emacs-f90-ts-mode/issues

Questions and discussions:
  https://fortran-lang.discourse.group/t/tree-sitter-based-f90-mode-for-emacs/10746

Note: Emacs must be linked against tree-sitter 0.25.x at runtime.
Emacs does not yet support 0.26, though support is in development and this
restriction may soon be obsolete.
Moreover the grammar should also be compiled against tree-sitter 0.25.x,
though it seems that grammar files generated by 0.26 work as well.
The pregenerated grammar files in the master branch of
https://github.com/mscfd/tree-sitter-fortran are built against 0.25.10
and ready to use, if there are problems with the official repository.

To verify the setup:
  M-: (treesit-library-abi-version)           ; should return 15
  M-: (treesit-language-abi-version 'fortran) ; should return 15

  in linux:
  ldd "emacs" | grep libtree-sitter ; should show libtree-sitter.so.0.25

  in macos:
  otool -L "emacs" | grep tree-sitter
  ; expecting something like: .../tree-sitter/lib/libtree-sitter.0.dylib
                              (compatibility version 0.0.0, current version 0.25.0)

  in windows: unknown how to check