Checking stage0 compiler artifacts {rustc-main, rustc_abi, rustc_arena, rustc_ast, rustc_ast_ir, rustc_ast_lowering, rustc_ast_passes, rustc_ast_pretty, rustc_attr_data_structures, rustc_attr_parsing, rustc_baked_icu_data, rustc_borrowck, rustc_builtin_macros, rustc_codegen_llvm, rustc_codegen_ssa, rustc_const_eval, rustc_data_structures, rustc_driver, rustc_driver_impl, rustc_error_codes, rustc_error_messages, rustc_errors, rustc_expand, rustc_feature, rustc_fluent_macro, rustc_fs_util, rustc_graphviz, rustc_hir, rustc_hir_analysis, rustc_hir_pretty, rustc_hir_typeck, rustc_incremental, rustc_index, rustc_index_macros, rustc_infer, rustc_interface, rustc_lexer, rustc_lint, rustc_lint_defs, rustc_llvm, rustc_log, rustc_macros, rustc_metadata, rustc_middle, rustc_mir_build, rustc_mir_dataflow, rustc_mir_transform, rustc_monomorphize, rustc_next_trait_solver, rustc_parse, rustc_parse_format, rustc_passes, rustc_pattern_analysis, rustc_privacy, rustc_query_impl, rustc_query_system, rustc_resolve, rustc_sanitizers, rustc_serialize, rustc_session, rustc_smir, rustc_span, rustc_symbol_mangling, rustc_target, rustc_trait_selection, rustc_traits, rustc_transmute, rustc_ty_utils, rustc_type_ir, rustc_type_ir_macros, stable_mir} (x86_64-unknown-linux-gnu)
Finished `release` profile [optimized + debuginfo] target(s) in 0.23s
Checking stage0 bootstrap artifacts (x86_64-unknown-linux-gnu)
Checking bootstrap v0.0.0 (/home/joe/repos/rust/src/bootstrap)
Finished `release` profile [optimized + debuginfo] target(s) in 0.64s
DEBUG bootstrap checking for postponed test failures from `test --no-fail-fast`
Build completed successfully in 0:00:08
```
#### Controlling tracing output
The env var `BOOTSTRAP_TRACING` accepts a [`tracing` env-filter][tracing-env-filter].
There are two orthogonal ways to control which kind of tracing logs you want:
1. You can specify the log **level**, e.g. `DEBUG` or `TRACE`.
2. You can also control the log **target**, e.g. `bootstrap` or `bootstrap::core::config` vs custom targets like `CONFIG_HANDLING`.
- Custom targets are used to limit what is output when `BOOTSTRAP_TRACING=bootstrap=TRACE` is used, as they can be too verbose even for `TRACE` level by default. Currently used custom targets:
- `CONFIG_HANDLING`
The `TRACE` filter will enable *all* `trace` level or less verbose level tracing output.
You can of course combine them (custom target logs are typically gated behind `TRACE` log level additionally):