fix(wasm): resolve playground "env" module error#39
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The wasm-bindgen generated JS contains `import * from "env"` statements for 12 C stdlib functions that tree-sitter needs (malloc, free, fprintf, etc.). Browsers cannot resolve bare module specifiers, causing the playground to fail on load. Fix: add an import map to index.html that maps "env" to a local env.js shim providing no-op stubs. The Rust allocator handles actual memory management via wasm-bindgen; these C stubs exist only to satisfy WebAssembly.instantiate. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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JuanMarchetto
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Feb 26, 2026
jeanclawdbotdamn
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Feb 26, 2026
tree-sitter's C code references malloc/free/fprintf/etc. which become unresolved "env" imports in the WASM binary. Browsers cannot resolve the bare "env" module specifier, causing the playground to fail. Previous fix (PR #39) added JS shims via import map, but malloc returning NULL caused tree-sitter to call abort() at runtime. This fix provides real #[no_mangle] implementations in Rust: - malloc/calloc/realloc/free: route to Rust's global allocator with an 8-byte size header so free/realloc can reconstruct the Layout - fprintf/snprintf/vsnprintf/fwrite/fputc/fclose: no-op stubs (tree-sitter declares but never calls these in the validation path) - clock: returns 0 - abort: triggers wasm32::unreachable trap The linker resolves these at build time, eliminating all "env" imports from the generated JS. Removes the now-unnecessary env.js shim and import map. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Uncaught TypeError: Failed to resolve module specifier "env"import * from "env"for 12 C stdlib functions tree-sitter needs (malloc,free,calloc,realloc,abort,fprintf,snprintf,vsnprintf,fclose,clock,fwrite,fputc). Browsers cannot resolve bare module specifiers.index.htmlmapping"env"→./pkg/env.js, and provide a shim with no-op stubs for all 12 functionsWebAssembly.instantiateFiles changed
playground/env.jsplayground/index.html<script type="importmap">.github/workflows/pages.ymlenv.jsto_site/pkg/Test plan
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