Accept versioned tree-sitter language grammar files

By discussion on emacs-devel, titled "Versioned Tree-sitter parser
libraries".

* src/treesit.c (Vtreesit_str_dot_0): New variable.
(treesit_load_language_push_for_each_suffix): Additionally look for
lib_base_name.0 and lib_base_name.0.0.
(syms_of_treesit): Initialize Vtreesit_str_dot_0.

1 files changed, 16 insertions, 2 deletions

diff --git a/src/treesit.c b/src/treesit.c
index 53dbeb68882..2d0df10ec44 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -404,6 +404,7 @@ init_treesit_functions (void)
 
 static Lisp_Object Vtreesit_str_libtree_sitter;
 static Lisp_Object Vtreesit_str_tree_sitter;
+static Lisp_Object Vtreesit_str_dot_0;
 static Lisp_Object Vtreesit_str_dot;
 static Lisp_Object Vtreesit_str_question_mark;
 static Lisp_Object Vtreesit_str_star;
@@ -529,8 +530,19 @@ treesit_load_language_push_for_each_suffix (Lisp_Object lib_base_name,
   suffixes = Vdynamic_library_suffixes;
 
   FOR_EACH_TAIL (suffixes)
-    *path_candidates = Fcons (concat2 (lib_base_name, XCAR (suffixes)),
-                              *path_candidates);
+    {
+      Lisp_Object candidate1 = concat2 (lib_base_name, XCAR (suffixes));
+      /* Support libraries named with ABI version numbers.  In the
+         foreseeable future we only need to support version 0.0.  See
+         the thread titled "Versioned Tree-sitter parser libraries" on
+         emacs-devel.  */
+      Lisp_Object candidate2 = concat2 (candidate1, Vtreesit_str_dot_0);
+      Lisp_Object candidate3 = concat2 (candidate2, Vtreesit_str_dot_0);
+
+      *path_candidates = Fcons (candidate3, *path_candidates);
+      *path_candidates = Fcons (candidate2, *path_candidates);
+      *path_candidates = Fcons (candidate1, *path_candidates);
+    }
 }
 
 /* Load the dynamic library of LANGUAGE_SYMBOL and return the pointer
@@ -3583,6 +3595,8 @@ then in the system default locations for dynamic libraries, in that order.  */);
   Vtreesit_str_libtree_sitter = build_pure_c_string ("libtree-sitter-");
   staticpro (&Vtreesit_str_tree_sitter);
   Vtreesit_str_tree_sitter = build_pure_c_string ("tree-sitter-");
+  staticpro (&Vtreesit_str_dot_0);
+  Vtreesit_str_dot_0 = build_pure_c_string (".0");
   staticpro (&Vtreesit_str_dot);
   Vtreesit_str_dot = build_pure_c_string (".");
   staticpro (&Vtreesit_str_question_mark);