c-static-analysis

# C/C++ static analysis (src/) Use this after you modify a runtime/codegen C/C++ source file under `src/` (not headers). Note that runtime changes also require a rebuild (`make -j`). Run static analysis checks: - First run `make -C src install-analysis-deps` to initialize dependencies (only needed once the first time, or after the LLVM/Clang toolchain dependencies change). This may download and install LLVM/Clang artifacts. - For a source file such as `src/jloptions.c` or `src/codegen.cpp`, use the file stem without the `.c`/`.cpp` extension: ```sh make -C src analyze-<file-stem> -j8 [--output-sync] ``` For example, to analyze `src/jloptions.c`, run: ```sh make -C src analyze-jloptions -j8 ``` Add `--output-sync` when your `make` supports it to keep parallel output grouped; otherwise omit it. - Checks can also be rerun individually with `clang-sa-<file-stem>`, `clang-sagc-<file-stem>`, `clang-safety-<file-stem>` or `clang-tidy-<file-stem>`. ## Fixing the GC-rooting checker (clang-sagc) If `clang-sagc-<file-stem>` fails, first look for fixes that establish real rooting, such as adding appropriate `JL_GC_PUSH`/`JL_GC_POP` scopes, or for lock/control-flow fixes. Do not add `JL_GC_PROMISE_ROOTED` without explicit user or maintainer confirmation. `JL_GC_PROMISE_ROOTED` asserts that a value is already rooted; it does not root the value. If it appears necessary, stop and ask for confirmation, showing the exact expression, the existing root that makes it safe, and the safepoints considered. - Remember arguments are assumed rooted, so check the callers to make sure that is handled. - As a diagnostic hint when asking for confirmation: if the value is temporarily moved through a struct or arraylist and then reloaded, the promised expression may need to refer to the reloaded field, such as `JL_GC_PROMISE_ROOTED(struct->field)`, immediately after the reload and before any use of that field. - If confirmed, put the promise as early in the code as is legal, near the definition or reload rather than the use.