commit_analysis.md

Upstream Rust Compiler Commits Analysis (320 commits)

1. Stabilized Features (Features moved from nightly to stable)

• assert_matches - Stabilize the assert_matches! macro for pattern matching assertions
• atomic_try_update - Stabilize atomic compare-and-swap update operations
• core::hint::cold_path - Stabilize hint for marking cold execution paths
• Const ControlFlow predicates - Stabilize const evaluation of ControlFlow methods
• New inclusive range type and iter - Stabilize new range type and iterator functionality
• int_from_ascii for NonZero<T> - Implement ASCII parsing for non-zero integers

2. New Language Features (New syntax, semantics, or capabilities)

• Pattern types in libcore - Start using pattern types (experimental type system feature)
• Heterogeneous & homogeneous try blocks - Implement try { } blocks with type-flexible error handling
• MVP for opaque generic const arguments (mGCA) - Major work on generic const arguments including:
  • Support for type const syntax (type const <IDENT> = <EXPR>)
  • Associated const obligations in well-formedness checking
  • Support for directly represented negated literals
  • Require #[type_const] on free consts
  • Transform args for inherent type_consts
• Truthy/falsy values - Allow non-boolean values in conditions
• Optional chaining - Support for ?. and ?? operators (related to your fork!)
• unreachable_cfg_select_predicates lint - New lint for unreachable cfg predicates

3. Standard Library Additions (New APIs, types, methods)

• BinaryHeap::from_raw_vec - Construct BinaryHeap from raw Vec without validation
• NonZero::<T>::from_str_radix - Parse non-zero integers with custom radix
• std::path normalize methods - Introduce path normalization at top of std::path
• TrustedLen for ArrayWindows - Implement trusted length trait for array windows iterator
• TrustedRandomAccess for ArrayWindows - Implement trusted random access for array windows
• FusedIterator for ArrayWindows - Implement fused iterator for array windows
• Stdio FD constants - Implement standard file descriptor constants
• const { 'Σ'.len_utf8() } - Enable const UTF-8 length computation

4. Major Internal Refactors (Significant compiler architecture changes)

Query System Overhaul (largest refactor category):

• Move rustc_query_system::plumbing to rustc_query_impl::execution - Major reorganization (parts 1 & 2)
• Move rustc_query_system::cache to rustc_middle::traits - Rename Cache as WithDepNodeCache
• Move rustc_middle::query::values to rustc_query_impl - Query value handling reorganization
• Move rustc_query_system::query::job parts to rustc_middle::job - Job tracking reorganization
• Move try_get_cached from rustc_query_system to rustc_middle - Cache lookup reorganization
• Remove trait QueryDispatcher - Simplify query dispatch mechanism
• Remove QueryDispatcherUnerased::Dispatcher associated type - Simplification
• Clarify names of QueryVTable functions - Better naming for query execution
• Clean up query macros for cache_on_disk_if - Macro simplification
• Rename JobOwner to ActiveJobGuard - Better naming
• Include key_hash in ActiveJobGuard - Add hash for active jobs
• Derive Clone for QueryJob and QueryLatch - Enable cloning
• Move needs-drop check for arena_cache queries out of macro code - Simplification
• Provide cycle handler for GenericPredicates - Prevent cycles in trait resolution
• Prevent cycles when lowering from supertrait elaboration - Cycle prevention

Diagnostics Infrastructure Overhaul (major migration):

• Remove fluent infrastructure - Major removal of localization system:
  • Remove DiagMessage::FluentIdentifier
  • Remove slugs from #[derive(Diagnostic)] macro
  • Remove fallback bundle
  • Remove fluent tests in rustc_error
  • Remove rustc_fluent_macro
  • Remove tidy fluent file checks
  • Remove ui-fulldeps tests for slugs
• Convert to inline diagnostics - Massive migration across crates:
  • rustc_lint
  • rustc_parse
  • rustc_const_eval
  • rustc_mir_build
  • rustc_passes
• Remove SubdiagMessage in favour of DiagMessage - Unification
• Convert impl Subdiagnostic to derives - Use macros instead of manual impls
• Remove empty subdiagnostics - Cleanup

Attribute Parser Migration (systematic port to new parser):

• Port to new attribute parser:
  • #![test_runner]
  • rustc_object_lifetime_default
  • rustc_no_mir_inline
  • rustc_trivial_field_reads
  • rustc_never_type_options
  • rustc_capture_analysis
  • rustc_conversion_suggestion
  • rustc_deprecated_safe_2024
  • rustc_expected_cgu_reuse
  • rustc_no_implicit_bounds
  • rustc_reservation_impl
  • rustc_strict_coherence
  • rustc_insignificant_dtor
  • rustc_outlives
  • rustc_evaluate_where_clauses
  • rustc_delayed_bug_from_inside_query
  • rustc_regions
  • rustc_intrinsic_const_stable_indirect
  • rustc_intrinsic
  • rustc_symbol_name
  • rustc_def_path

Other Major Refactors:

• Modularize custom fork code to reduce merge conflicts - Your custom fork refactor!
• Move impl Interner for TyCtxt to its own submodule - Better organization
• Move ADT related code to sub module for type info - Type reflection organization
• Uplift Predicate::allow_normalization to rustc_type_ir - Move to shared IR
• Move target machine factory error reporting into codegen backend - Better separation
• Use cg_ssa's produce_final_output_artifacts in cg_clif - Code sharing
• Remove tm_factory field from CodegenContext - Simplification
• Streamline rustc_span::HashStableContext - Hash stability improvements
• Tweak query key trait bounds - Trait bound refinement
• Borrowck: simplify diagnostics for placeholders - Borrow checker simplification

5. Diagnostics Improvements (Better error messages)

• Fix suggestion on CallToDeprecatedSafeFnRequiresUnsafe - Better unsafe hints
• Fix help on AmbiguousMissingKwForItemSub - Clearer keyword suggestions
• Fix suggestion on AutoTraitItems - Better auto-trait diagnostics
• Add help message suggesting explicit reference cast for From/TryFrom - Better conversion hints
• Modernize diagnostic for indeterminate trait object lifetime bounds - Clearer lifetime messages
• Fix diagnostics in closure signature mismatch - Better closure error messages
• Add note for ?Sized params in int-ptr casts diag - Better cast diagnostics
• Add note when inherent impl for alias type defined outside crate - Better type alias hints
• rustc_parse: improve error diagnostic for "missing let" - Better let binding errors
• rustc_parse_format: improve diagnostics for unsupported debug = syntax - Better format string errors
• Fix error spans for asm!() args that are macros - Better inline assembly diagnostics
• borrowck: suggest &mut *x for pattern reborrows - Better reborrow suggestions
• Suppress unused_mut lint if mutation fails due to borrowck error - Reduce noise
• Split parse_inner_attr errors by case - More specific attribute errors
• Split ComparisonOrShiftInterpretedAsGenericSugg - More specific generic suggestions
• Use display_source_code() in ReferenceConversion - Show source in diagnostics
• Cover more cases for parentheses in &(impl Trait1 + Trait2) - Better trait bound formatting

6. Bug Fixes (Notable fixes)

• Fix issue #152482, #152004, #151124, #152347 - Various ICE fixes
• Fix copy-paste bug in report_sub_sup_conflict - Used wrong trace cause
• Fix rustdoc macro call highlighting - Correctly detect macro calls
• Fix bound var resolution for trait aliases - Trait alias type resolution
• Fix ICE in vtable iteration for trait reference in const eval - Const eval crash fix
• Fix SourceFile::normalized_byte_pos - File position calculation
• Fix passing/returning structs with 64-bit SPARC ABI - SPARC ABI correctness
• Fix lockfile - Cargo.lock issues
• prevent incorrect layout error - Layout computation fix
• GVN: Do not unify dereferences if they are references - Optimization soundness
• GVN: Do not introduce new dereferences if they borrow from non-SSA locals - Optimization safety
• GVN: Remove invalidate_derefs - Fix optimization bug
• Handle race when coloring nodes concurrently as both green and red - Concurrency fix
• Weaken assert_dep_node_not_yet_allocated_in_current_session for multiple threads - Multi-threading fix
• Correctly implement client side request cancellation support - LSP cancellation
• Avoid bogus THIR span for let x = offset_of!(..) - Better span tracking
• std: Don't panic when removing nonexistent UEFI var - UEFI robustness
• libm: Fix acoshf and acosh for negative inputs - Math library correctness
• libm: Fix tests for lgamma - Math library testing
• Infer expected len in include_bytes!() to avoid mismatches - Macro correctness
• Fix not complete .not in condition - Boolean operator fix
• fix linking of postcard test - Test infrastructure fix
• Allow deprecated(since = "CURRENT_RUSTC_VERSION") - Deprecation system fix
• check stalled coroutine obligations eagerly - Async/generator fix
• Fix rustdoc links for BoundRegionKind/BoundTyKind - Documentation links

7. Platform/Target Changes (New targets, platform-specific changes)

New Targets:

• s390x-unknown-none-softfloat - New bare-metal s390x target with software floating point
• Add avr_target_feature - AVR target feature support
• Require sram target feature on AVR - AVR memory requirement

Target Improvements:

• Bump tvOS, visionOS and watchOS Aarch64 targets to tier 2 - Apple platform promotion
• Disable profiler runtime on tvOS and watchOS - Apple platform fixes
• Fix @needs-backends compiletest directive - Better backend testing
• Set crt_static_allow_dylibs to true for Emscripten target - Emscripten linking
• hexagon: Make fma label local to avoid symbol collision - Hexagon platform fix
• Implement __sync builtins for thumbv6-none-eabi - ARM Cortex-M0 atomics

Target Refactors:

• Renamed RustcAbi::X86Softfloat to Softfloat - Made platform-agnostic
• Allow for variant aliases in target_spec_enum! - Target spec flexibility

8. CI/Infrastructure (Build system, CI changes)

Build System:

• ./rebuild.sh and ./rebuild.sh cache - Your custom build scripts!
• Update to LLVM 22 rc 3 - LLVM version bump
• Update to Xcode 26.2 - macOS toolchain update
• Update wasi-sdk used in CI/releases - WebAssembly toolchain
• Always use default Clang on macOS - macOS build simplification
• Remove AR=ar env var - Build cleanup
• Remove USE_XCODE_CLANG - Build simplification
• Remove -Alinker-messages - Build output cleanup
• Unset WINAPI_NO_BUNDLED_LIBRARIES - Windows build fix
• Only set CFG_COMPILER_HOST_TRIPLE when building rustc - Build optimization
• Remove a couple of unnecessary stage checks - Build simplification
• bootstrap: always propagate CARGO_TARGET_{host}_LINKER - Build consistency
• Set codegen-units=1 for benchmarks - Benchmark optimization

CI Updates:

• ci: Pin rustc on native PowerPC job - CI stability
• ci: Temporarily disable native PPC and s390x jobs - CI maintenance
• ci: Update all docker images to latest version - Container updates
• ci: Enable verbose output for josh-sync - Better CI logging
• triagebot: Switch to check-commits = "uncanonicalized" - Commit checking
• compiletest: -Zunstable-options for json targets - Test infrastructure
• Disable the run-make/translation test for now - Test maintenance
• Ignore all debuginfo tests for LLDB that we do not run in CI - Test cleanup

Documentation:

• improve build docs - Better build documentation
• Update CI documentation for branch names - CI docs update
• Fix typos and capitalization across documentation - Documentation cleanup
• Fix typos and grammar in top-level and src/doc documentation - More doc cleanup
• Use relative paths for std links in rustc-docs - Better doc linking
• Document -Zcache-proc-macros - Proc macro caching docs
• Document feature gate checking - Feature gate system docs
• Add cross-links between feature gate docs - Better doc navigation
• Clarify and reorganize feature-gate-check doc - Feature gate clarity
• Update translation documentation - Translation system docs
• Update diagnostics documentation - Diagnostics system docs
• Update documentation of rustc_macros - Macro system docs

Dependency Updates:

• Update cargo submodule (multiple times) - Cargo updates
• Bump salsa - Salsa dependency update
• Bump time from 0.3.44 to 0.3.47 - Security/bug fix update
• meta: Upgrade all dependencies to latest compatible versions - Mass dependency update
• meta: Switch to workspace dependencies - Cargo workspace improvement
• meta: Sort Cargo.toml [features] table after [dependencies] - Cargo.toml organization
• Remove unused fluent-syntax dependency from tidy - Dependency cleanup

Project Organization:

• Update books - Rust book updates
• Remove compiler adhoc group - Triagebot cleanup
• Remove project-exploit-mitigations adhoc group - Triagebot cleanup
• Remove project-stable-mir adhoc group - Triagebot cleanup
• Remove project-const-traits adhoc group - Triagebot cleanup
• Remove types adhoc group - Triagebot cleanup
• Remove rustdoc adhoc group - Triagebot cleanup
• Add reddevilmidzy to review group - Reviewer addition
• re-add TaKO8Ki to triagebot review queue - Reviewer re-addition
• Add 'C-date-reference-triage' to exclude_labels - Triage automation
• Add label for date reference triage - Triage labels

9. Type System & Const Generics Work

• Support unions in type info reflection - Type reflection for unions
• Support enums in type info reflection - Type reflection for enums
• Support structs in type info reflection - Type reflection for structs
• Add generics info for structs in type info - Generic type reflection
• Simplify writing of tuple type info - Tuple type reflection optimization
• Erase type lifetime before writing type ID - Type ID computation
• Introduce helper ty::Generics::has_own_self - Generics helper method
• Use .map.collect to aggregate in .to_ty of tuples - Type conversion optimization
• Fix bound var resolution for trait aliases - Trait alias type resolution

10. Code Quality & Cleanup

• Remove now-unnecessary indirection - Code simplification (multiple instances)
• cleanup: Perform some simplifications possible with the MSRV bump - Use newer features
• Bump the libm MSRV to 1.67 - Minimum version bump
• Format heterogeneous try blocks - Formatting improvement
• style: remove unneeded trailing commas - Style cleanup
• Simplify redundant description - Documentation cleanup
• Remove some empty subdiagnostics - Dead code removal
• Remove a couple of unused errors - Dead code removal
• Remove unused comments related to SyntaxErrorKind - Comment cleanup
• Remove outdated fixme - Comment cleanup
• Remove out-of-date comment - Comment cleanup
• Fix typo (multiple) - Typo fixes
• Allow more capitalized words - Spellcheck update
• deduplicate Tag enum - Code deduplication
• remove Closure generics - Simplification
• remove 'static in many places - Lifetime simplification
• expand define_reify_functions! - Macro expansion
• keep const blocks around - Const evaluation improvement

11. Testing Improvements

• Add tests for issues 152004, 151124, 152347 - Regression tests
• Add regression test for macro call highlighting - Rustdoc test
• Add regression test for inherent type_const normalization - Type system test
• Reorganize tests that no longer crash - Move from crashes/ to ui/
• Move tests from tests/crashes to tests/ui now that they don't ICE - Test organization
• Add ui test insufficient-suggestion-issue-141679.rs - Diagnostics test
• Regression test for let x = offset_of!(..) else { .. } span - Span test
• Add miscompiled test cases for GVN - Optimization correctness tests
• add regression test - Generic regression test
• Add selection test case - Selection test
• Add test case for select non-first branch - Selection edge case
• cmse: additional argument passing tests - ARM security extension tests
• symcheck: Add tests for symbol checker - Symbol checking tests
• symcheck: Check for core symbols with new mangling - Mangling test
• symcheck: Enable wasm by default - WebAssembly symbol checking
• add tests for s390x-unknown-none-softfloat - New target tests
• Add extra test to ensure highlighting for macros is working - Rustdoc test
• improve tests - Test quality improvement
• use test instead of unix to be platform-independent - Cross-platform tests
• libm-test: Remove exception for fmaximum_num tests - Math test improvement
• add test for simd from array repeat codegen - SIMD codegen test

12. Compiler Backend & Codegen

• Remove support for ScalarPair unadjusted arguments - ABI cleanup
• Don't compute FnAbi for LLVM intrinsics in backends - Optimization
• Reduce usage of FnAbi in codegen_llvm_intrinsic_call - Simplification
• extract TyAndLayout::peel_transparent_wrappers helper - Layout helper
• cmse: don't use BackendRepr when checking return type - ARM CMSE fix
• Stop having two different alignment constants - Deduplication
• Don't import TyCtxt from crate::ty::context - Import cleanup
• Indicate that bidirectional_lang_item_map! declares functions - Macro documentation
• Drop dump test for type info reflection - Test removal

13. Const Evaluation & MIR

• Also duplicate #[expect] attribute in #[derive]-ed code - Lint attribute handling
• Allow only a single accepter per attribute - Attribute validation
• Prevent const stability attrs from being applied to macros - Const stability fix
• Restrict the set of things that const stability can be applied - Const stability validation
• Remove accidental const stability marker on a struct - Const stability fix
• Split ol mapper into more specific to/kernel/from mapper - Optimization refactor
• Add some conversion trait impls - Trait implementations
• use mem::conjure_zst directly - ZST handling
• make with_api! take explicit type paths - Macro improvement
• simplify some other generics - Generic simplification

14. Safety & Security

• FCW for derive helper attributes that will conflict with built-in attributes - Future compatibility warning
• Replace some feature(core_intrinsics) with stable hints - Reduce unsafe surface
• Remove unnecessary unsafe(non_update_types) - Safety cleanup
• Prevent incorrect layout error - Memory safety
• RwLock: refine documentation to emphasize non-reentrancy guarantees - Concurrency safety docs
• BikeshedGuaranteedNoDrop trait: add comments that it can be observed on stable - Safety documentation

15. Lints & Warnings

• add unreachable_cfg_select_predicates lint - New lint for cfg predicates
• make the lint more sophisticated - Lint improvement
• Suppress unused_mut lint if mutation fails due to borrowck error - Reduce false positives
• Allow unstable_name_collisions - Lint exemption

Summary Statistics

Most Active Areas:

1. Query System Refactor (~25 commits) - Major architectural cleanup
2. Diagnostics Infrastructure (~30 commits) - Removal of fluent, inline diagnostics
3. Attribute Parser Migration (~20 commits) - Systematic modernization
4. Generic Const Arguments (mGCA) (~10 commits) - Major feature development
5. Type Info Reflection (~7 commits) - New type system capability

Most Significant Changes:

• mGCA implementation - Major new language feature for const generics
• Try blocks - New control flow construct
• Query system overhaul - Massive internal refactor for maintainability
• Fluent removal - Complete removal of localization infrastructure
• Attribute parser migration - Systematic modernization of ~20 attributes

Breaking Changes:

• Remove ScalarPair unadjusted arguments (ABI change)
• Remove support for old diagnostic infrastructure (internal)
• Various const stability restrictions (compile-time)

Your Fork's Relevance: Several upstream commits relate to features you've already implemented:

• Optional chaining (?., ??) - you have this!
• Truthy/falsy values - you have this!
• Try blocks - you have similar features
• String operations - you have extensive string methods
• Math operators (**, ≈) - you have these!

This analysis shows Rust is actively investing in const generics, improving diagnostics, and doing major internal cleanup while maintaining stability.