Future-proof loading tree-sitter library on MS-Windows

* src/treesit.c (syms_of_treesit) <tree-sitter--library-abi>: New
internal variable.

* lisp/term/w32-win.el (dynamic-library-alist): Use
'tree-sitter--library-abi' to select a proper libtree-sitter DLL
version.

2 files changed, 23 insertions, 2 deletions

diff --git a/lisp/term/w32-win.el b/lisp/term/w32-win.el
index 3c0acf368f4..2a59ec2460d 100644
--- a/lisp/term/w32-win.el
+++ b/lisp/term/w32-win.el
@@ -290,8 +290,18 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
        '(lcms2 "liblcms2-2.dll")
        '(gccjit "libgccjit-0.dll")
        ;; MSYS2 distributes libtree-sitter.dll, without API version
-       ;; number...
-       '(tree-sitter "libtree-sitter.dll" "libtree-sitter-0.dll")))
+       ;; number, upto and including version 0.24.3-2; later versions
+       ;; come with libtree-sitter-major.minor.dll (as in
+       ;; libtree-sitter-0.24.dll).  Sadly, the header files don't have
+       ;; any symbols for library version, so we can only use the
+       ;; library-language ABI version; according to
+       ;; https://github.com/tree-sitter/tree-sitter/issues/3925, the
+       ;; language ABI must change when the library's ABI is modified.
+       (if (<= tree-sitter--library-abi 14)
+           '(tree-sitter "libtree-sitter-0.24.dll"
+                         "libtree-sitter.dll"
+                         "libtree-sitter-0.dll")
+         '(tree-sitter "libtree-sitter-0.25.dll"))))
 
 ;;; multi-tty support
 (defvar w32-initialized nil
diff --git a/src/treesit.c b/src/treesit.c
index 679b8fc7ddd..4031d80f7c9 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -4371,4 +4371,15 @@ the symbol of that THING.  For example, (or sexp sentence).  */);
   defsubr (&Streesit_subtree_stat);
 #endif /* HAVE_TREE_SITTER */
   defsubr (&Streesit_available_p);
+#ifdef WINDOWSNT
+  DEFSYM (Qtree_sitter__library_abi, "tree-sitter--library-abi");
+  Fset (Qtree_sitter__library_abi,
+#if HAVE_TREE_SITTER
+        make_fixnum (TREE_SITTER_LANGUAGE_VERSION)
+#else
+        make_fixnum (-1)
+#endif
+        );
+#endif
+
 }