config.compiler.toml

# These defaults are meant for contributors to the compiler who do not modify codegen or LLVM
[build]
# Contributors working on the compiler will probably expect compiler docs to be generated.
compiler-docs = true

[rust]
# This enables `RUSTC_LOG=debug`, avoiding confusing situations
# where adding `debug!()` appears to do nothing.
# However, it makes running the compiler slightly slower.
debug-logging = true
# Get actually-useful information from backtraces, profiling, etc. with minimal added bytes
debuginfo-level = "line-tables-only"
# This greatly increases the speed of rebuilds, especially when there are only minor changes. However, it makes the initial build slightly slower.
incremental = true
# Print backtrace on internal compiler errors during bootstrap
backtrace-on-ice = true
# Make the compiler and standard library faster to build, at the expense of a ~20% runtime slowdown.
lto = "off"
# Forces frame pointers to be used with `-Cforce-frame-pointers`.
# This can be helpful for profiling at a small performance cost.
frame-pointers = true

[llvm]
# Having this set to true disrupts compiler development workflows for people who use `llvm.download-ci-llvm = true`
# because we don't provide ci-llvm on the `rustc-alt-builds` server. Therefore, it is kept off by default.
assertions = false
# Enable warnings during the LLVM compilation (when LLVM is changed, causing a compilation)
enable-warnings = true
# Will download LLVM from CI if available on your platform.
download-ci-llvm = "if-unchanged"