Merge #1850 #1851

1850: Update GCC/Rust files per 'contrib/update-copyright.py --this-year' [#1831] r=tschwinge a=tschwinge

Fixes: #1831
1851: Merge upstream (dummy), 2023-01-31 GCC/Rust upstreaming r=tschwinge a=tschwinge

In #1847 "Merge upstream, last commit before 2023-01-31 GCC/Rust upstreaming"
we merged commit 9e56306f4d7c15e7667d8ac0b62ae6efb93ba756 from upstream GCC
master branch.

This one now merges the 2023-01-31 GCC/Rust upstreaming, commits
9e56306f4d7c15e7667d8ac0b62ae6efb93ba756..50335ddd301404e9053786b26a23a924471b4d09:

      - 5be4c2687a89 gccrs: session-manager: Add ast-pretty-expanded dump
      - e66fec8e6ba3 gccrs: const folding port
      - ff8a56950776 gccrs: Desugar double borrows into two HIR:BorrowExpr's
      - 86743891a6e9 gccrs: backend: Expose Bvariable class through rust-gcc header
      - 41547275c5e9 gccrs: builtins: Add add_overflow builtin and refactor class
      - 9c87dc0afe05 gccrs: backend: Add overflow checks to every arithmetic operation
      - 3a3a352091b7 gccrs: rustc_attrs: Allow `rustc_inherit_overflow_checks` as a builtin..
      - 938facc5e93a gccrs: lint: Do not emit unused warnings for public items
      - f7014b28b81f gccrs: parser: Parse RangeFullExpr without erroring out
      - 1fed030c1651 gccrs: macros: Handle matchers properly in repetitions
      - 252216dd0c59 gccrs: transcriber: Do not infinite loop if the current parsed node is an error
      - 7dc41901213d gccrs: dump: Add AST debugging using the AST::Dump class
      - 55fb35c51b2e gccrs: ast: Only expand expressions and types if the kind is right
      - 3663d7ef6662 gccrs: ast: Add better assertion on AST fragments
      - 245ce6f26a16 gccrs: Add guards against getting data from an empty vector
      - af22b54af53c gccrs: Add missing location info to coercions
      - 7ad24d802e59 gccrs: Refactor unify to hit a unify_site
      - 1eabeb5aecc9 gccrs: Remove param_use_canonical_types checks ported from c++ front-end
      - ffa16a4590ad gccrs: Create canonical process of compiling constant items
      - 43cb42a3d82d gccrs: Add extra debugging for method call expressions
      - e641158a5f5c gccrs: Add new check for contains_associated_types
      - 0fffc0e772d6 gccrs: Unit structs are not concrete when they need substitutions
      - 689a5c6711b8 gccrs: bugfix: initialize slice from array in const context
      - b0ff1647cbe6 gccrs: add testcase to test component_ref and constructor codes in eval_constant_expression()
      - e6a3886a833a gccrs: backend: correctly formulate the exit condition ...
      - dd9d6656e9a4 gccrs: add testcase with struct to test component_ref and constructor codes..
      - 0d5adf093566 gccrs: testsuite: add loop condition execution test
      - 288b6298a6ae gccrs: const generics: Make sure const generic types are visited properly
      - ff9d7741d4b9 gccrs: const generics: Forbid default values in Functions, Traits and Impls
      - 739d0509ed55 gccrs: attributes: Add #[macro_use] as builtin
      - 3736647947b6 gccrs: module lowering: Do not append null pointers as items
      - 70fc174b78a2 gccrs: Static Items must be const evaluated
      - 408ab8a6e412 gccrs: Statics are a coercion site
      - a0c2ea3ee6e4 gccrs: remove bad assertion
      - f92f8ee75bf0 gccrs: Add testcase for const-eval issue from rust-blog
      - 9d6b434e1fda gccrs: rust: Add -frust-compile-until option
      - e88ce5cc6847 gccrs: expand: eager evaluate macros inside builtin macros
      - c6c4342273a7 gccrs: testsuite/rust: add a testcase for testing ...
      - e1beb624ff5a gccrs: Cleanup formatting of backend expression visitor
      - 9c60f0e1e5cd gccrs: Make constexpr constructors type-checking more permissive
      - 11a37f895040 gccrs: Fix duplicated function generation on higher ranked trait bounds
      - 104cc285533e gccrs: Refactor TypeResolution to be a simple query based system
      - d9d7b6ccd45a gccrs: Add testcase to show forward declared items work
      - 50335ddd3014 gccrs: Add testcase to show forward declared items work via TypeAlias

This merge is done with 'git merge --strategy=ours', so effectively doesn't
merge any changes.  Rationale: those commits are taken from GCC/Rust master
branch, and any remaining changes we'd either like to persist, or assess
individually, later.

Co-authored-by: Thomas Schwinge <thomas@codesourcery.com>
Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>
Co-authored-by: Faisal Abbas <90.abbasfaisal@gmail.com>
Co-authored-by: Philip Herron <philip.herron@embecosm.com>
Co-authored-by: liushuyu <liushuyu011@gmail.com>