Module cargo::ops::fix

High-level overview of how fix works:

The main goal is to run cargo check to get rustc to emit JSON diagnostics with suggested fixes that can be applied to the files on the filesystem, and validate that those changes didn’t break anything.

Cargo begins by launching a LockServer thread in the background to listen for network connections to coordinate locking when multiple targets are built simultaneously. It ensures each package has only one fix running at once.

The RustfixDiagnosticServer is launched in a background thread (in JobQueue) to listen for network connections to coordinate displaying messages to the user on the console (so that multiple processes don’t try to print at the same time).

Cargo begins a normal cargo check operation with itself set as a proxy for rustc by setting primary_unit_rustc in the build config. When cargo launches rustc to check a crate, it is actually launching itself. The FIX_ENV_INTERNAL environment variable is set so that cargo knows it is in fix-proxy-mode.

Each proxied cargo-as-rustc detects it is in fix-proxy-mode (via FIX_ENV_INTERNAL environment variable in main) and does the following:

• Acquire a lock from the LockServer from the master cargo process.
• Launches the real rustc (rustfix_and_fix), looking at the JSON output for suggested fixes.
• Uses the rustfix crate to apply the suggestions to the files on the file system.
• If rustfix fails to apply any suggestions (for example, they are overlapping), but at least some suggestions succeeded, it will try the previous two steps up to 4 times as long as some suggestions succeed.
• Assuming there’s at least one suggestion applied, and the suggestions applied cleanly, rustc is run again to verify the suggestions didn’t break anything. The change will be backed out if it fails (unless --broken-code is used).

Structs

• FixArgs 🔒
  Various command-line options and settings used when cargo is running as a proxy for rustc during the fix operation.
• FixOptions
• FixedCrate 🔒
• FixedFile 🔒

Constants

• BROKEN_CODE_ENV_INTERNAL 🔒
  Internal only. For passing FixOptions::broken_code through to cargo running in proxy mode.
• EDITION_ENV_INTERNAL 🔒
  Internal only. For passing FixOptions::edition through to cargo running in proxy mode.
• FIX_ENV_INTERNAL 🔒
  Internal only. Indicates Cargo is in fix-proxy-mode if presents. The value of it is the socket address of the LockServer being used. See the module-level documentation for more.
• IDIOMS_ENV_INTERNAL 🔒
  Internal only. For passing FixOptions::idioms through to cargo running in proxy mode.
• SYSROOT_INTERNAL 🔒
  Internal only. The sysroot path.

Functions

• add_feature_for_unused_deps 🔒
• check_resolver_change 🔒
• check_version_control 🔒
• emit_output 🔒
• exit_with 🔒
• fix
• fix_exec_rustc
  Entry point for cargo running as a proxy for rustc.
• fix_get_proxy_lock_addr
  Provide the lock address when running in proxy mode
• log_failed_fix 🔒
• migrate_manifests 🔒
• rename_array_of_target_fields_2024 🔒
• rename_dep_fields_2024 🔒
• rename_table 🔒
• rename_target_fields_2024 🔒
• report_maybe_diesel 🔒
• rustfix_and_fix 🔒
  Executes rustc to apply one round of suggestions to the crate in question.
• rustfix_crate 🔒
  Attempts to apply fixes to a single crate.