Allocate tree-sitter's external scanners from the same Zig allocator as its runtime

2026-10-01T03:12:14Z

syntax.zig points the tree-sitter runtime at a Zig allocator, but the grammars' external scanners did not follow it. A grammar's tree_sitter/alloc.h maps ts_malloc to the runtime's current allocator only when TREE_SITTER_REUSE_ALLOCATOR is defined, and plain malloc otherwise, so every scanner's state and its arrays came from libc. Five scanners (bash, markdown, markdown_inline, python, typst) also call malloc, calloc, realloc and free by name. build.zig now compiles every grammar with TREE_SITTER_REUSE_ALLOCATOR and forces in src/tree_sitter_heap.h, which includes stdlib.h and then defines the four names as calls through ts_current_malloc and friends. A header forced in from the build rather than a patch to the grammars keeps zig-pkg pristine. No grammar archive refers to libc's allocator any more; only the runtime does, for its defaults. A scanner frees only what it allocated itself, and the syntax tests that create and destroy a parser for every grammar under a leak-checking allocator pass. Co-Authored-By: Claude Opus 5.5 (1M context)

pardes.git/src/tree_sitter_heap.h, branch release-0.24

Allocate tree-sitter's external scanners from the same Zig allocator as its runtime