Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

22 files changed, 906 insertions, 447 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 6cce95427..0dc0dee86 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -11,7 +11,7 @@ use rustc_metadata::find_native_static_library;
 use rustc_metadata::fs::{emit_metadata, METADATA_FILENAME};
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
-use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, LdImpl, Strip};
+use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, LdImpl, Lto, Strip};
 use rustc_session::config::{OutputFilenames, OutputType, PrintRequest, SplitDwarfKind};
 use rustc_session::cstore::DllImport;
 use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
@@ -23,20 +23,23 @@ use rustc_session::{filesearch, Session};
 use rustc_span::symbol::Symbol;
 use rustc_span::DebuggerVisualizerFile;
 use rustc_target::spec::crt_objects::{CrtObjects, LinkSelfContainedDefault};
-use rustc_target::spec::{LinkOutputKind, LinkerFlavor, LldFlavor, SplitDebuginfo};
-use rustc_target::spec::{PanicStrategy, RelocModel, RelroLevel, SanitizerSet, Target};
+use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, LinkerFlavorCli, Lld, PanicStrategy};
+use rustc_target::spec::{RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo, Target};
 
 use super::archive::{ArchiveBuilder, ArchiveBuilderBuilder};
 use super::command::Command;
 use super::linker::{self, Linker};
 use super::metadata::{create_rmeta_file, MetadataPosition};
 use super::rpath::{self, RPathConfig};
-use crate::{looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, NativeLib};
+use crate::{
+    errors, looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, NativeLib,
+};
 
 use cc::windows_registry;
 use regex::Regex;
 use tempfile::Builder as TempFileBuilder;
 
+use itertools::Itertools;
 use std::borrow::Borrow;
 use std::cell::OnceCell;
 use std::collections::BTreeSet;
@@ -93,7 +96,7 @@ pub fn link_binary<'a>(
             let tmpdir = TempFileBuilder::new()
                 .prefix("rustc")
                 .tempdir()
-                .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err)));
+                .unwrap_or_else(|error| sess.emit_fatal(errors::CreateTempDir { error }));
             let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps);
             let out_filename = out_filename(
                 sess,
@@ -206,11 +209,29 @@ pub fn link_binary<'a>(
 }
 
 pub fn each_linked_rlib(
+    sess: &Session,
     info: &CrateInfo,
     f: &mut dyn FnMut(CrateNum, &Path),
-) -> Result<(), String> {
+) -> Result<(), errors::LinkRlibError> {
     let crates = info.used_crates.iter();
     let mut fmts = None;
+
+    let lto_active = matches!(sess.lto(), Lto::Fat | Lto::Thin);
+    if lto_active {
+        for combination in info.dependency_formats.iter().combinations(2) {
+            let (ty1, list1) = &combination[0];
+            let (ty2, list2) = &combination[1];
+            if list1 != list2 {
+                return Err(errors::LinkRlibError::IncompatibleDependencyFormats {
+                    ty1: format!("{ty1:?}"),
+                    ty2: format!("{ty2:?}"),
+                    list1: format!("{list1:?}"),
+                    list2: format!("{list2:?}"),
+                });
+            }
+        }
+    }
+
     for (ty, list) in info.dependency_formats.iter() {
         match ty {
             CrateType::Executable
@@ -220,30 +241,31 @@ pub fn each_linked_rlib(
                 fmts = Some(list);
                 break;
             }
+            CrateType::Dylib if lto_active => {
+                fmts = Some(list);
+                break;
+            }
             _ => {}
         }
     }
     let Some(fmts) = fmts else {
-        return Err("could not find formats for rlibs".to_string());
+        return Err(errors::LinkRlibError::MissingFormat);
     };
     for &cnum in crates {
         match fmts.get(cnum.as_usize() - 1) {
             Some(&Linkage::NotLinked | &Linkage::IncludedFromDylib) => continue,
             Some(_) => {}
-            None => return Err("could not find formats for rlibs".to_string()),
+            None => return Err(errors::LinkRlibError::MissingFormat),
         }
-        let name = info.crate_name[&cnum];
+        let crate_name = info.crate_name[&cnum];
         let used_crate_source = &info.used_crate_source[&cnum];
         if let Some((path, _)) = &used_crate_source.rlib {
             f(cnum, &path);
         } else {
             if used_crate_source.rmeta.is_some() {
-                return Err(format!(
-                    "could not find rlib for: `{}`, found rmeta (metadata) file",
-                    name
-                ));
+                return Err(errors::LinkRlibError::OnlyRmetaFound { crate_name });
             } else {
-                return Err(format!("could not find rlib for: `{}`", name));
+                return Err(errors::LinkRlibError::NotFound { crate_name });
             }
         }
     }
@@ -340,10 +362,7 @@ fn link_rlib<'a>(
                 // -whole-archive and it isn't clear how we can currently handle such a
                 // situation correctly.
                 // See https://github.com/rust-lang/rust/issues/88085#issuecomment-901050897
-                sess.err(
-                    "the linking modifiers `+bundle` and `+whole-archive` are not compatible \
-                        with each other when generating rlibs",
-                );
+                sess.emit_err(errors::IncompatibleLinkingModifiers);
             }
             NativeLibKind::Static { bundle: None | Some(true), .. } => {}
             NativeLibKind::Static { bundle: Some(false), .. }
@@ -365,12 +384,8 @@ fn link_rlib<'a>(
                 ));
                 continue;
             }
-            ab.add_archive(&location, Box::new(|_| false)).unwrap_or_else(|e| {
-                sess.fatal(&format!(
-                    "failed to add native library {}: {}",
-                    location.to_string_lossy(),
-                    e
-                ));
+            ab.add_archive(&location, Box::new(|_| false)).unwrap_or_else(|error| {
+                sess.emit_fatal(errors::AddNativeLibrary { library_path: location, error });
             });
         }
     }
@@ -386,8 +401,8 @@ fn link_rlib<'a>(
             true,
         );
 
-        ab.add_archive(&output_path, Box::new(|_| false)).unwrap_or_else(|e| {
-            sess.fatal(&format!("failed to add native library {}: {}", output_path.display(), e));
+        ab.add_archive(&output_path, Box::new(|_| false)).unwrap_or_else(|error| {
+            sess.emit_fatal(errors::AddNativeLibrary { library_path: output_path, error });
         });
     }
 
@@ -452,14 +467,11 @@ fn collate_raw_dylibs<'a, 'b>(
                     // FIXME: when we add support for ordinals, figure out if we need to do anything
                     // if we have two DllImport values with the same name but different ordinals.
                     if import.calling_convention != old_import.calling_convention {
-                        sess.span_err(
-                            import.span,
-                            &format!(
-                                "multiple declarations of external function `{}` from \
-                                 library `{}` have different calling conventions",
-                                import.name, name,
-                            ),
-                        );
+                        sess.emit_err(errors::MultipleExternalFuncDecl {
+                            span: import.span,
+                            function: import.name,
+                            library_name: &name,
+                        });
                     }
                 }
             }
@@ -502,7 +514,7 @@ fn link_staticlib<'a>(
     )?;
     let mut all_native_libs = vec![];
 
-    let res = each_linked_rlib(&codegen_results.crate_info, &mut |cnum, path| {
+    let res = each_linked_rlib(sess, &codegen_results.crate_info, &mut |cnum, path| {
         let name = codegen_results.crate_info.crate_name[&cnum];
         let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
 
@@ -561,7 +573,7 @@ fn link_staticlib<'a>(
         all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
     });
     if let Err(e) = res {
-        sess.fatal(&e);
+        sess.emit_fatal(e);
     }
 
     ab.build(out_filename);
@@ -674,9 +686,7 @@ fn link_dwarf_object<'a>(
     }) {
         Ok(()) => {}
         Err(e) => {
-            sess.struct_err("linking dwarf objects with thorin failed")
-                .note(&format!("{:?}", e))
-                .emit();
+            sess.emit_err(errors::ThorinErrorWrapper(e));
             sess.abort_if_errors();
         }
     }
@@ -749,8 +759,7 @@ fn link_natively<'a>(
         // then it should not default to linking executables as pie. Different
         // versions of gcc seem to use different quotes in the error message so
         // don't check for them.
-        if sess.target.linker_is_gnu
-            && flavor != LinkerFlavor::Ld
+        if matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
             && unknown_arg_regex.is_match(&out)
             && out.contains("-no-pie")
             && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie")
@@ -768,8 +777,7 @@ fn link_natively<'a>(
 
         // Detect '-static-pie' used with an older version of gcc or clang not supporting it.
         // Fallback from '-static-pie' to '-static' in that case.
-        if sess.target.linker_is_gnu
-            && flavor != LinkerFlavor::Ld
+        if matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
             && unknown_arg_regex.is_match(&out)
             && (out.contains("-static-pie") || out.contains("--no-dynamic-linker"))
             && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-static-pie")
@@ -882,29 +890,20 @@ fn link_natively<'a>(
                 let mut output = prog.stderr.clone();
                 output.extend_from_slice(&prog.stdout);
                 let escaped_output = escape_string(&output);
-                let mut err = sess.struct_err(&format!(
-                    "linking with `{}` failed: {}",
-                    linker_path.display(),
-                    prog.status
-                ));
-                err.note(&format!("{:?}", &cmd)).note(&escaped_output);
-                if escaped_output.contains("undefined reference to") {
-                    err.help(
-                        "some `extern` functions couldn't be found; some native libraries may \
-                         need to be installed or have their path specified",
-                    );
-                    err.note("use the `-l` flag to specify native libraries to link");
-                    err.note("use the `cargo:rustc-link-lib` directive to specify the native \
-                              libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#cargorustc-link-libkindname)");
-                }
-                err.emit();
-
+                // FIXME: Add UI tests for this error.
+                let err = errors::LinkingFailed {
+                    linker_path: &linker_path,
+                    exit_status: prog.status,
+                    command: &cmd,
+                    escaped_output: &escaped_output,
+                };
+                sess.diagnostic().emit_err(err);
                 // If MSVC's `link.exe` was expected but the return code
                 // is not a Microsoft LNK error then suggest a way to fix or
                 // install the Visual Studio build tools.
                 if let Some(code) = prog.status.code() {
                     if sess.target.is_like_msvc
-                        && flavor == LinkerFlavor::Msvc
+                        && flavor == LinkerFlavor::Msvc(Lld::No)
                         // Respect the command line override
                         && sess.opts.cg.linker.is_none()
                         // Match exactly "link.exe"
@@ -980,9 +979,10 @@ fn link_natively<'a>(
                      but `link.exe` was not found",
                 );
                 sess.note_without_error(
-                    "please ensure that VS 2013, VS 2015, VS 2017, VS 2019 or VS 2022 \
-                     was installed with the Visual C++ option",
+                    "please ensure that Visual Studio 2017 or later, or Build Tools \
+                     for Visual Studio were installed with the Visual C++ option.",
                 );
+                sess.note_without_error("VS Code is a different product, and is not sufficient.");
             }
             sess.abort_if_errors();
         }
@@ -1035,16 +1035,36 @@ fn link_natively<'a>(
 
     if sess.target.is_like_osx {
         match (strip, crate_type) {
-            (Strip::Debuginfo, _) => strip_symbols_in_osx(sess, &out_filename, Some("-S")),
+            (Strip::Debuginfo, _) => {
+                strip_symbols_with_external_utility(sess, "strip", &out_filename, Some("-S"))
+            }
             // Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988)
             (Strip::Symbols, CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro) => {
-                strip_symbols_in_osx(sess, &out_filename, Some("-x"))
+                strip_symbols_with_external_utility(sess, "strip", &out_filename, Some("-x"))
+            }
+            (Strip::Symbols, _) => {
+                strip_symbols_with_external_utility(sess, "strip", &out_filename, None)
             }
-            (Strip::Symbols, _) => strip_symbols_in_osx(sess, &out_filename, None),
             (Strip::None, _) => {}
         }
     }
 
+    if sess.target.os == "illumos" {
+        // Many illumos systems will have both the native 'strip' utility and
+        // the GNU one. Use the native version explicitly and do not rely on
+        // what's in the path.
+        let stripcmd = "/usr/bin/strip";
+        match strip {
+            // Always preserve the symbol table (-x).
+            Strip::Debuginfo => {
+                strip_symbols_with_external_utility(sess, stripcmd, &out_filename, Some("-x"))
+            }
+            // Strip::Symbols is handled via the --strip-all linker option.
+            Strip::Symbols => {}
+            Strip::None => {}
+        }
+    }
+
     Ok(())
 }
 
@@ -1056,8 +1076,13 @@ fn strip_value(sess: &Session) -> Strip {
     }
 }
 
-fn strip_symbols_in_osx<'a>(sess: &'a Session, out_filename: &Path, option: Option<&str>) {
-    let mut cmd = Command::new("strip");
+fn strip_symbols_with_external_utility<'a>(
+    sess: &'a Session,
+    util: &str,
+    out_filename: &Path,
+    option: Option<&str>,
+) {
+    let mut cmd = Command::new(util);
     if let Some(option) = option {
         cmd.arg(option);
     }
@@ -1068,14 +1093,14 @@ fn strip_symbols_in_osx<'a>(sess: &'a Session, out_filename: &Path, option: Opti
                 let mut output = prog.stderr.clone();
                 output.extend_from_slice(&prog.stdout);
                 sess.struct_warn(&format!(
-                    "stripping debug info with `strip` failed: {}",
-                    prog.status
+                    "stripping debug info with `{}` failed: {}",
+                    util, prog.status
                 ))
                 .note(&escape_string(&output))
                 .emit();
             }
         }
-        Err(e) => sess.fatal(&format!("unable to run `strip`: {}", e)),
+        Err(e) => sess.fatal(&format!("unable to run `{}`: {}", util, e)),
     }
 }
 
@@ -1091,11 +1116,12 @@ fn add_sanitizer_libraries(sess: &Session, crate_type: CrateType, linker: &mut d
     // both executables and dynamic shared objects. Everywhere else the runtimes
     // are currently distributed as static libraries which should be linked to
     // executables only.
-    let needs_runtime = match crate_type {
-        CrateType::Executable => true,
-        CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => sess.target.is_like_osx,
-        CrateType::Rlib | CrateType::Staticlib => false,
-    };
+    let needs_runtime = !sess.target.is_like_android
+        && match crate_type {
+            CrateType::Executable => true,
+            CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => sess.target.is_like_osx,
+            CrateType::Rlib | CrateType::Staticlib => false,
+        };
 
     if !needs_runtime {
         return;
@@ -1187,7 +1213,10 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
             // only the linker flavor is known; use the default linker for the selected flavor
             (None, Some(flavor)) => Some((
                 PathBuf::from(match flavor {
-                    LinkerFlavor::Gcc => {
+                    LinkerFlavor::Gnu(Cc::Yes, _)
+                    | LinkerFlavor::Darwin(Cc::Yes, _)
+                    | LinkerFlavor::WasmLld(Cc::Yes)
+                    | LinkerFlavor::Unix(Cc::Yes) => {
                         if cfg!(any(target_os = "solaris", target_os = "illumos")) {
                             // On historical Solaris systems, "cc" may have
                             // been Sun Studio, which is not flag-compatible
@@ -1200,9 +1229,14 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
                             "cc"
                         }
                     }
-                    LinkerFlavor::Ld => "ld",
-                    LinkerFlavor::Lld(_) => "lld",
-                    LinkerFlavor::Msvc => "link.exe",
+                    LinkerFlavor::Gnu(_, Lld::Yes)
+                    | LinkerFlavor::Darwin(_, Lld::Yes)
+                    | LinkerFlavor::WasmLld(..)
+                    | LinkerFlavor::Msvc(Lld::Yes) => "lld",
+                    LinkerFlavor::Gnu(..) | LinkerFlavor::Darwin(..) | LinkerFlavor::Unix(..) => {
+                        "ld"
+                    }
+                    LinkerFlavor::Msvc(..) => "link.exe",
                     LinkerFlavor::EmCc => {
                         if cfg!(windows) {
                             "emcc.bat"
@@ -1227,15 +1261,20 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
                     || stem == "clang"
                     || stem.ends_with("-clang")
                 {
-                    LinkerFlavor::Gcc
+                    LinkerFlavor::from_cli(LinkerFlavorCli::Gcc, &sess.target)
                 } else if stem == "wasm-ld" || stem.ends_with("-wasm-ld") {
-                    LinkerFlavor::Lld(LldFlavor::Wasm)
-                } else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") {
-                    LinkerFlavor::Ld
-                } else if stem == "link" || stem == "lld-link" {
-                    LinkerFlavor::Msvc
+                    LinkerFlavor::WasmLld(Cc::No)
+                } else if stem == "ld" || stem.ends_with("-ld") {
+                    LinkerFlavor::from_cli(LinkerFlavorCli::Ld, &sess.target)
+                } else if stem == "ld.lld" {
+                    LinkerFlavor::Gnu(Cc::No, Lld::Yes)
+                } else if stem == "link" {
+                    LinkerFlavor::Msvc(Lld::No)
+                } else if stem == "lld-link" {
+                    LinkerFlavor::Msvc(Lld::Yes)
                 } else if stem == "lld" || stem == "rust-lld" {
-                    LinkerFlavor::Lld(sess.target.lld_flavor)
+                    let lld_flavor = sess.target.linker_flavor.lld_flavor();
+                    LinkerFlavor::from_cli(LinkerFlavorCli::Lld(lld_flavor), &sess.target)
                 } else {
                     // fall back to the value in the target spec
                     sess.target.linker_flavor
@@ -1249,7 +1288,8 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
 
     // linker and linker flavor specified via command line have precedence over what the target
     // specification specifies
-    let linker_flavor = sess.opts.cg.linker_flavor.map(LinkerFlavor::from_cli);
+    let linker_flavor =
+        sess.opts.cg.linker_flavor.map(|flavor| LinkerFlavor::from_cli(flavor, &sess.target));
     if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), linker_flavor) {
         return ret;
     }
@@ -1320,7 +1360,7 @@ fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLib]) {
                     let verbatim = lib.verbatim.unwrap_or(false);
                     if sess.target.is_like_msvc {
                         Some(format!("{}{}", name, if verbatim { "" } else { ".lib" }))
-                    } else if sess.target.linker_is_gnu {
+                    } else if sess.target.linker_flavor.is_gnu() {
                         Some(format!("-l{}{}", if verbatim { ":" } else { "" }, name))
                     } else {
                         Some(format!("-l{}", name))
@@ -1607,7 +1647,7 @@ fn add_pre_link_objects(
     let empty = Default::default();
     let objects = if self_contained {
         &opts.pre_link_objects_self_contained
-    } else if !(sess.target.os == "fuchsia" && flavor == LinkerFlavor::Gcc) {
+    } else if !(sess.target.os == "fuchsia" && matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))) {
         &opts.pre_link_objects
     } else {
         &empty
@@ -1647,7 +1687,7 @@ fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor)
 fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) {
     match (crate_type, &sess.target.link_script) {
         (CrateType::Cdylib | CrateType::Executable, Some(script)) => {
-            if !sess.target.linker_is_gnu {
+            if !sess.target.linker_flavor.is_gnu() {
                 sess.fatal("can only use link script when linking with GNU-like linker");
             }
 
@@ -1890,7 +1930,7 @@ fn add_rpath_args(
             out_filename: out_filename.to_path_buf(),
             has_rpath: sess.target.has_rpath,
             is_like_osx: sess.target.is_like_osx,
-            linker_is_gnu: sess.target.linker_is_gnu,
+            linker_is_gnu: sess.target.linker_flavor.is_gnu(),
         };
         cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
     }
@@ -2134,7 +2174,7 @@ fn add_order_independent_options(
 
     if sess.target.os == "fuchsia"
         && crate_type == CrateType::Executable
-        && flavor != LinkerFlavor::Gcc
+        && !matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
     {
         let prefix = if sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
             "asan/"
@@ -2747,12 +2787,12 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     let llvm_target = &sess.target.llvm_target;
     if sess.target.vendor != "apple"
         || !matches!(os.as_ref(), "ios" | "tvos" | "watchos" | "macos")
-        || (flavor != LinkerFlavor::Gcc && flavor != LinkerFlavor::Lld(LldFlavor::Ld64))
+        || !matches!(flavor, LinkerFlavor::Darwin(..))
     {
         return;
     }
 
-    if os == "macos" && flavor != LinkerFlavor::Lld(LldFlavor::Ld64) {
+    if os == "macos" && !matches!(flavor, LinkerFlavor::Darwin(Cc::No, _)) {
         return;
     }
 
@@ -2786,10 +2826,10 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     };
 
     match flavor {
-        LinkerFlavor::Gcc => {
+        LinkerFlavor::Darwin(Cc::Yes, _) => {
             cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
         }
-        LinkerFlavor::Lld(LldFlavor::Ld64) => {
+        LinkerFlavor::Darwin(Cc::No, _) => {
             cmd.args(&["-syslibroot", &sdk_root]);
         }
         _ => unreachable!(),
@@ -2852,7 +2892,10 @@ fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {
 
 fn add_gcc_ld_path(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     if let Some(ld_impl) = sess.opts.unstable_opts.gcc_ld {
-        if let LinkerFlavor::Gcc = flavor {
+        if let LinkerFlavor::Gnu(Cc::Yes, _)
+        | LinkerFlavor::Darwin(Cc::Yes, _)
+        | LinkerFlavor::WasmLld(Cc::Yes) = flavor
+        {
             match ld_impl {
                 LdImpl::Lld => {
                     // Implement the "self-contained" part of -Zgcc-ld
@@ -2867,7 +2910,7 @@ fn add_gcc_ld_path(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
                     // Implement the "linker flavor" part of -Zgcc-ld
                     // by asking cc to use some kind of lld.
                     cmd.arg("-fuse-ld=lld");
-                    if sess.target.lld_flavor != LldFlavor::Ld {
+                    if !flavor.is_gnu() {
                         // Tell clang to use a non-default LLD flavor.
                         // Gcc doesn't understand the target option, but we currently assume
                         // that gcc is not used for Apple and Wasm targets (#97402).
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index e505543b2..c49b19bdf 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -1,5 +1,6 @@
 use super::command::Command;
 use super::symbol_export;
+use crate::errors;
 use rustc_span::symbol::sym;
 
 use std::ffi::{OsStr, OsString};
@@ -16,7 +17,7 @@ use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo, S
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel, Strip};
 use rustc_session::Session;
-use rustc_target::spec::{LinkOutputKind, LinkerFlavor, LldFlavor};
+use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, Lld};
 
 use cc::windows_registry;
 
@@ -56,8 +57,13 @@ pub fn get_linker<'a>(
     let mut cmd = match linker.to_str() {
         Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker),
         _ => match flavor {
-            LinkerFlavor::Lld(f) => Command::lld(linker, f),
-            LinkerFlavor::Msvc if sess.opts.cg.linker.is_none() && sess.target.linker.is_none() => {
+            LinkerFlavor::Gnu(Cc::No, Lld::Yes)
+            | LinkerFlavor::Darwin(Cc::No, Lld::Yes)
+            | LinkerFlavor::WasmLld(Cc::No)
+            | LinkerFlavor::Msvc(Lld::Yes) => Command::lld(linker, flavor.lld_flavor()),
+            LinkerFlavor::Msvc(Lld::No)
+                if sess.opts.cg.linker.is_none() && sess.target.linker.is_none() =>
+            {
                 Command::new(msvc_tool.as_ref().map_or(linker, |t| t.path()))
             }
             _ => Command::new(linker),
@@ -68,9 +74,7 @@ pub fn get_linker<'a>(
     // To comply with the Windows App Certification Kit,
     // MSVC needs to link with the Store versions of the runtime libraries (vcruntime, msvcrt, etc).
     let t = &sess.target;
-    if (flavor == LinkerFlavor::Msvc || flavor == LinkerFlavor::Lld(LldFlavor::Link))
-        && t.vendor == "uwp"
-    {
+    if matches!(flavor, LinkerFlavor::Msvc(..)) && t.vendor == "uwp" {
         if let Some(ref tool) = msvc_tool {
             let original_path = tool.path();
             if let Some(ref root_lib_path) = original_path.ancestors().nth(4) {
@@ -126,23 +130,22 @@ pub fn get_linker<'a>(
     // to the linker args construction.
     assert!(cmd.get_args().is_empty() || sess.target.vendor == "uwp");
     match flavor {
-        LinkerFlavor::Gcc => {
-            Box::new(GccLinker { cmd, sess, target_cpu, hinted_static: false, is_ld: false })
-                as Box<dyn Linker>
-        }
-        LinkerFlavor::Ld if sess.target.os == "l4re" => {
+        LinkerFlavor::Unix(Cc::No) if sess.target.os == "l4re" => {
             Box::new(L4Bender::new(cmd, sess)) as Box<dyn Linker>
         }
-        LinkerFlavor::Lld(LldFlavor::Ld)
-        | LinkerFlavor::Lld(LldFlavor::Ld64)
-        | LinkerFlavor::Ld => {
-            Box::new(GccLinker { cmd, sess, target_cpu, hinted_static: false, is_ld: true })
-                as Box<dyn Linker>
-        }
-        LinkerFlavor::Lld(LldFlavor::Link) | LinkerFlavor::Msvc => {
-            Box::new(MsvcLinker { cmd, sess }) as Box<dyn Linker>
-        }
-        LinkerFlavor::Lld(LldFlavor::Wasm) => Box::new(WasmLd::new(cmd, sess)) as Box<dyn Linker>,
+        LinkerFlavor::WasmLld(Cc::No) => Box::new(WasmLd::new(cmd, sess)) as Box<dyn Linker>,
+        LinkerFlavor::Gnu(cc, _)
+        | LinkerFlavor::Darwin(cc, _)
+        | LinkerFlavor::WasmLld(cc)
+        | LinkerFlavor::Unix(cc) => Box::new(GccLinker {
+            cmd,
+            sess,
+            target_cpu,
+            hinted_static: false,
+            is_ld: cc == Cc::No,
+            is_gnu: flavor.is_gnu(),
+        }) as Box<dyn Linker>,
+        LinkerFlavor::Msvc(..) => Box::new(MsvcLinker { cmd, sess }) as Box<dyn Linker>,
         LinkerFlavor::EmCc => Box::new(EmLinker { cmd, sess }) as Box<dyn Linker>,
         LinkerFlavor::Bpf => Box::new(BpfLinker { cmd, sess }) as Box<dyn Linker>,
         LinkerFlavor::Ptx => Box::new(PtxLinker { cmd, sess }) as Box<dyn Linker>,
@@ -211,6 +214,7 @@ pub struct GccLinker<'a> {
     hinted_static: bool, // Keeps track of the current hinting mode.
     // Link as ld
     is_ld: bool,
+    is_gnu: bool,
 }
 
 impl<'a> GccLinker<'a> {
@@ -359,7 +363,7 @@ impl<'a> Linker for GccLinker<'a> {
     fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
         match output_kind {
             LinkOutputKind::DynamicNoPicExe => {
-                if !self.is_ld && self.sess.target.linker_is_gnu {
+                if !self.is_ld && self.is_gnu {
                     self.cmd.arg("-no-pie");
                 }
             }
@@ -373,7 +377,7 @@ impl<'a> Linker for GccLinker<'a> {
             LinkOutputKind::StaticNoPicExe => {
                 // `-static` works for both gcc wrapper and ld.
                 self.cmd.arg("-static");
-                if !self.is_ld && self.sess.target.linker_is_gnu {
+                if !self.is_ld && self.is_gnu {
                     self.cmd.arg("-no-pie");
                 }
             }
@@ -431,26 +435,26 @@ impl<'a> Linker for GccLinker<'a> {
                 // FIXME(81490): ld64 doesn't support these flags but macOS 11
                 // has -needed-l{} / -needed_library {}
                 // but we have no way to detect that here.
-                self.sess.warn("`as-needed` modifier not implemented yet for ld64");
-            } else if self.sess.target.linker_is_gnu && !self.sess.target.is_like_windows {
+                self.sess.emit_warning(errors::Ld64UnimplementedModifier);
+            } else if self.is_gnu && !self.sess.target.is_like_windows {
                 self.linker_arg("--no-as-needed");
             } else {
-                self.sess.warn("`as-needed` modifier not supported for current linker");
+                self.sess.emit_warning(errors::LinkerUnsupportedModifier);
             }
         }
         self.hint_dynamic();
-        self.cmd.arg(format!("-l{}{}", if verbatim { ":" } else { "" }, lib));
+        self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
         if !as_needed {
             if self.sess.target.is_like_osx {
                 // See above FIXME comment
-            } else if self.sess.target.linker_is_gnu && !self.sess.target.is_like_windows {
+            } else if self.is_gnu && !self.sess.target.is_like_windows {
                 self.linker_arg("--as-needed");
             }
         }
     }
     fn link_staticlib(&mut self, lib: &str, verbatim: bool) {
         self.hint_static();
-        self.cmd.arg(format!("-l{}{}", if verbatim { ":" } else { "" }, lib));
+        self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
     }
     fn link_rlib(&mut self, lib: &Path) {
         self.hint_static();
@@ -489,7 +493,7 @@ impl<'a> Linker for GccLinker<'a> {
             // FIXME(81490): ld64 as of macOS 11 supports the -needed_framework
             // flag but we have no way to detect that here.
             // self.cmd.arg("-needed_framework").arg(framework);
-            self.sess.warn("`as-needed` modifier not implemented yet for ld64");
+            self.sess.emit_warning(errors::Ld64UnimplementedModifier);
         }
         self.cmd.arg("-framework").arg(framework);
     }
@@ -504,11 +508,8 @@ impl<'a> Linker for GccLinker<'a> {
         self.hint_static();
         let target = &self.sess.target;
         if !target.is_like_osx {
-            self.linker_arg("--whole-archive").cmd.arg(format!(
-                "-l{}{}",
-                if verbatim { ":" } else { "" },
-                lib
-            ));
+            self.linker_arg("--whole-archive");
+            self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
             self.linker_arg("--no-whole-archive");
         } else {
             // -force_load is the macOS equivalent of --whole-archive, but it
@@ -553,21 +554,19 @@ impl<'a> Linker for GccLinker<'a> {
         // eliminate the metadata. If we're building an executable, however,
         // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
         // reduction.
-        } else if (self.sess.target.linker_is_gnu || self.sess.target.is_like_wasm)
-            && !keep_metadata
-        {
+        } else if (self.is_gnu || self.sess.target.is_like_wasm) && !keep_metadata {
             self.linker_arg("--gc-sections");
         }
     }
 
     fn no_gc_sections(&mut self) {
-        if self.sess.target.linker_is_gnu || self.sess.target.is_like_wasm {
+        if self.is_gnu || self.sess.target.is_like_wasm {
             self.linker_arg("--no-gc-sections");
         }
     }
 
     fn optimize(&mut self) {
-        if !self.sess.target.linker_is_gnu && !self.sess.target.is_like_wasm {
+        if !self.is_gnu && !self.sess.target.is_like_wasm {
             return;
         }
 
@@ -581,7 +580,7 @@ impl<'a> Linker for GccLinker<'a> {
     }
 
     fn pgo_gen(&mut self) {
-        if !self.sess.target.linker_is_gnu {
+        if !self.is_gnu {
             return;
         }
 
@@ -611,7 +610,13 @@ impl<'a> Linker for GccLinker<'a> {
         match strip {
             Strip::None => {}
             Strip::Debuginfo => {
-                self.linker_arg("--strip-debug");
+                // The illumos linker does not support --strip-debug although
+                // it does support --strip-all as a compatibility alias for -s.
+                // The --strip-debug case is handled by running an external
+                // `strip` utility as a separate step after linking.
+                if self.sess.target.os != "illumos" {
+                    self.linker_arg("--strip-debug");
+                }
             }
             Strip::Symbols => {
                 self.linker_arg("--strip-all");
@@ -667,8 +672,8 @@ impl<'a> Linker for GccLinker<'a> {
                     writeln!(f, "_{}", sym)?;
                 }
             };
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to write lib.def file: {}", e));
+            if let Err(error) = res {
+                self.sess.emit_fatal(errors::LibDefWriteFailure { error });
             }
         } else if is_windows {
             let res: io::Result<()> = try {
@@ -682,8 +687,8 @@ impl<'a> Linker for GccLinker<'a> {
                     writeln!(f, "  {}", symbol)?;
                 }
             };
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to write list.def file: {}", e));
+            if let Err(error) = res {
+                self.sess.emit_fatal(errors::LibDefWriteFailure { error });
             }
         } else {
             // Write an LD version script
@@ -699,8 +704,8 @@ impl<'a> Linker for GccLinker<'a> {
                 }
                 writeln!(f, "\n  local:\n    *;\n}};")?;
             };
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to write version script: {}", e));
+            if let Err(error) = res {
+                self.sess.emit_fatal(errors::VersionScriptWriteFailure { error });
             }
         }
 
@@ -752,13 +757,13 @@ impl<'a> Linker for GccLinker<'a> {
     fn add_no_exec(&mut self) {
         if self.sess.target.is_like_windows {
             self.linker_arg("--nxcompat");
-        } else if self.sess.target.linker_is_gnu {
+        } else if self.is_gnu {
             self.linker_arg("-znoexecstack");
         }
     }
 
     fn add_as_needed(&mut self) {
-        if self.sess.target.linker_is_gnu && !self.sess.target.is_like_windows {
+        if self.is_gnu && !self.sess.target.is_like_windows {
             self.linker_arg("--as-needed");
         } else if self.sess.target.is_like_solaris {
             // -z ignore is the Solaris equivalent to the GNU ld --as-needed option
@@ -917,9 +922,8 @@ impl<'a> Linker for MsvcLinker<'a> {
                                     self.cmd.arg(arg);
                                 }
                             }
-                            Err(err) => {
-                                self.sess
-                                    .warn(&format!("error enumerating natvis directory: {}", err));
+                            Err(error) => {
+                                self.sess.emit_warning(errors::NoNatvisDirectory { error });
                             }
                         }
                     }
@@ -973,8 +977,8 @@ impl<'a> Linker for MsvcLinker<'a> {
                 writeln!(f, "  {}", symbol)?;
             }
         };
-        if let Err(e) = res {
-            self.sess.fatal(&format!("failed to write lib.def file: {}", e));
+        if let Err(error) = res {
+            self.sess.emit_fatal(errors::LibDefWriteFailure { error });
         }
         let mut arg = OsString::from("/DEF:");
         arg.push(path);
@@ -1174,22 +1178,19 @@ impl<'a> WasmLd<'a> {
         //   sharing memory and instantiating the module multiple times. As a
         //   result if it were exported then we'd just have no sharing.
         //
-        // * `--export=__wasm_init_memory` - when using `--passive-segments` the
-        //   linker will synthesize this function, and so we need to make sure
-        //   that our usage of `--export` below won't accidentally cause this
-        //   function to get deleted.
-        //
-        // * `--export=*tls*` - when `#[thread_local]` symbols are used these
-        //   symbols are how the TLS segments are initialized and configured.
+        // On wasm32-unknown-unknown, we also export symbols for glue code to use:
+        //    * `--export=*tls*` - when `#[thread_local]` symbols are used these
+        //      symbols are how the TLS segments are initialized and configured.
         if sess.target_features.contains(&sym::atomics) {
             cmd.arg("--shared-memory");
             cmd.arg("--max-memory=1073741824");
             cmd.arg("--import-memory");
-            cmd.arg("--export=__wasm_init_memory");
-            cmd.arg("--export=__wasm_init_tls");
-            cmd.arg("--export=__tls_size");
-            cmd.arg("--export=__tls_align");
-            cmd.arg("--export=__tls_base");
+            if sess.target.os == "unknown" {
+                cmd.arg("--export=__wasm_init_tls");
+                cmd.arg("--export=__tls_size");
+                cmd.arg("--export=__tls_align");
+                cmd.arg("--export=__tls_base");
+            }
         }
         WasmLd { cmd, sess }
     }
@@ -1314,10 +1315,12 @@ impl<'a> Linker for WasmLd<'a> {
 
         // LLD will hide these otherwise-internal symbols since it only exports
         // symbols explicitly passed via the `--export` flags above and hides all
-        // others. Various bits and pieces of tooling use this, so be sure these
-        // symbols make their way out of the linker as well.
-        self.cmd.arg("--export=__heap_base");
-        self.cmd.arg("--export=__data_end");
+        // others. Various bits and pieces of wasm32-unknown-unknown tooling use
+        // this, so be sure these symbols make their way out of the linker as well.
+        if self.sess.target.os == "unknown" {
+            self.cmd.arg("--export=__heap_base");
+            self.cmd.arg("--export=__data_end");
+        }
     }
 
     fn subsystem(&mut self, _subsystem: &str) {}
@@ -1438,7 +1441,7 @@ impl<'a> Linker for L4Bender<'a> {
 
     fn export_symbols(&mut self, _: &Path, _: CrateType, _: &[String]) {
         // ToDo, not implemented, copy from GCC
-        self.sess.warn("exporting symbols not implemented yet for L4Bender");
+        self.sess.emit_warning(errors::L4BenderExportingSymbolsUnimplemented);
         return;
     }
 
@@ -1730,8 +1733,8 @@ impl<'a> Linker for BpfLinker<'a> {
                 writeln!(f, "{}", sym)?;
             }
         };
-        if let Err(e) = res {
-            self.sess.fatal(&format!("failed to write symbols file: {}", e));
+        if let Err(error) = res {
+            self.sess.emit_fatal(errors::SymbolFileWriteFailure { error });
         } else {
             self.cmd.arg("--export-symbols").arg(&path);
         }
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 8d7e2c5cf..c2ecc4160 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -13,7 +13,7 @@ use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::{self, SymbolName, TyCtxt};
-use rustc_session::config::CrateType;
+use rustc_session::config::{CrateType, OomStrategy};
 use rustc_target::spec::SanitizerSet;
 
 pub fn threshold(tcx: TyCtxt<'_>) -> SymbolExportLevel {
@@ -76,7 +76,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap<
             // let it through if it's included statically.
             match tcx.hir().get_by_def_id(def_id) {
                 Node::ForeignItem(..) => {
-                    tcx.is_statically_included_foreign_item(def_id).then_some(def_id)
+                    tcx.native_library(def_id).map_or(false, |library| library.kind.is_statically_included()).then_some(def_id)
                 }
 
                 // Only consider nodes that actually have exported symbols.
@@ -206,6 +206,15 @@ fn exported_symbols_provider_local<'tcx>(
                 },
             ));
         }
+
+        symbols.push((
+            ExportedSymbol::NoDefId(SymbolName::new(tcx, OomStrategy::SYMBOL)),
+            SymbolExportInfo {
+                level: SymbolExportLevel::Rust,
+                kind: SymbolExportKind::Text,
+                used: false,
+            },
+        ));
     }
 
     if tcx.sess.instrument_coverage() || tcx.sess.opts.cg.profile_generate.enabled() {
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 68f3b19b7..d0ac016b0 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -2,11 +2,11 @@ use super::link::{self, ensure_removed};
 use super::lto::{self, SerializedModule};
 use super::symbol_export::symbol_name_for_instance_in_crate;
 
+use crate::errors;
+use crate::traits::*;
 use crate::{
     CachedModuleCodegen, CodegenResults, CompiledModule, CrateInfo, ModuleCodegen, ModuleKind,
 };
-
-use crate::traits::*;
 use jobserver::{Acquired, Client};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
@@ -15,7 +15,10 @@ use rustc_data_structures::profiling::TimingGuard;
 use rustc_data_structures::profiling::VerboseTimingGuard;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::emitter::Emitter;
-use rustc_errors::{translation::Translate, DiagnosticId, FatalError, Handler, Level};
+use rustc_errors::{
+    translation::{to_fluent_args, Translate},
+    DiagnosticId, FatalError, Handler, Level,
+};
 use rustc_fs_util::link_or_copy;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_incremental::{
@@ -113,7 +116,6 @@ pub struct ModuleConfig {
     pub vectorize_slp: bool,
     pub merge_functions: bool,
     pub inline_threshold: Option<u32>,
-    pub new_llvm_pass_manager: Option<bool>,
     pub emit_lifetime_markers: bool,
     pub llvm_plugins: Vec<String>,
 }
@@ -265,7 +267,6 @@ impl ModuleConfig {
             },
 
             inline_threshold: sess.opts.cg.inline_threshold,
-            new_llvm_pass_manager: sess.opts.unstable_opts.new_llvm_pass_manager,
             emit_lifetime_markers: sess.emit_lifetime_markers(),
             llvm_plugins: if_regular!(sess.opts.unstable_opts.llvm_plugins.clone(), vec![]),
         }
@@ -532,7 +533,7 @@ fn produce_final_output_artifacts(
     // Produce final compile outputs.
     let copy_gracefully = |from: &Path, to: &Path| {
         if let Err(e) = fs::copy(from, to) {
-            sess.err(&format!("could not copy {:?} to {:?}: {}", from, to, e));
+            sess.emit_err(errors::CopyPath::new(from, to, e));
         }
     };
 
@@ -548,7 +549,7 @@ fn produce_final_output_artifacts(
                 ensure_removed(sess.diagnostic(), &path);
             }
         } else {
-            let ext = crate_output
+            let extension = crate_output
                 .temp_path(output_type, None)
                 .extension()
                 .unwrap()
@@ -559,19 +560,11 @@ fn produce_final_output_artifacts(
             if crate_output.outputs.contains_key(&output_type) {
                 // 2) Multiple codegen units, with `--emit foo=some_name`.  We have
                 //    no good solution for this case, so warn the user.
-                sess.warn(&format!(
-                    "ignoring emit path because multiple .{} files \
-                                    were produced",
-                    ext
-                ));
+                sess.emit_warning(errors::IgnoringEmitPath { extension });
             } else if crate_output.single_output_file.is_some() {
                 // 3) Multiple codegen units, with `-o some_name`.  We have
                 //    no good solution for this case, so warn the user.
-                sess.warn(&format!(
-                    "ignoring -o because multiple .{} files \
-                                    were produced",
-                    ext
-                ));
+                sess.emit_warning(errors::IgnoringOutput { extension });
             } else {
                 // 4) Multiple codegen units, but no explicit name.  We
                 //    just leave the `foo.0.x` files in place.
@@ -882,14 +875,12 @@ fn execute_copy_from_cache_work_item<B: ExtraBackendMethods>(
         );
         match link_or_copy(&source_file, &output_path) {
             Ok(_) => Some(output_path),
-            Err(err) => {
-                let diag_handler = cgcx.create_diag_handler();
-                diag_handler.err(&format!(
-                    "unable to copy {} to {}: {}",
-                    source_file.display(),
-                    output_path.display(),
-                    err
-                ));
+            Err(error) => {
+                cgcx.create_diag_handler().emit_err(errors::CopyPathBuf {
+                    source_file,
+                    output_path,
+                    error,
+                });
                 None
             }
         }
@@ -1008,6 +999,14 @@ fn start_executing_work<B: ExtraBackendMethods>(
     let coordinator_send = tx_to_llvm_workers;
     let sess = tcx.sess;
 
+    let mut each_linked_rlib_for_lto = Vec::new();
+    drop(link::each_linked_rlib(sess, crate_info, &mut |cnum, path| {
+        if link::ignored_for_lto(sess, crate_info, cnum) {
+            return;
+        }
+        each_linked_rlib_for_lto.push((cnum, path.to_path_buf()));
+    }));
+
     // Compute the set of symbols we need to retain when doing LTO (if we need to)
     let exported_symbols = {
         let mut exported_symbols = FxHashMap::default();
@@ -1029,7 +1028,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
             }
             Lto::Fat | Lto::Thin => {
                 exported_symbols.insert(LOCAL_CRATE, copy_symbols(LOCAL_CRATE));
-                for &cnum in tcx.crates(()).iter() {
+                for &(cnum, ref _path) in &each_linked_rlib_for_lto {
                     exported_symbols.insert(cnum, copy_symbols(cnum));
                 }
                 Some(Arc::new(exported_symbols))
@@ -1049,14 +1048,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
         })
         .expect("failed to spawn helper thread");
 
-    let mut each_linked_rlib_for_lto = Vec::new();
-    drop(link::each_linked_rlib(crate_info, &mut |cnum, path| {
-        if link::ignored_for_lto(sess, crate_info, cnum) {
-            return;
-        }
-        each_linked_rlib_for_lto.push((cnum, path.to_path_buf()));
-    }));
-
     let ol =
         if tcx.sess.opts.unstable_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() {
             // If we know that we won’t be doing codegen, create target machines without optimisation.
@@ -1639,7 +1630,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         llvm_start_time: &mut Option<VerboseTimingGuard<'a>>,
     ) {
         if config.time_module && llvm_start_time.is_none() {
-            *llvm_start_time = Some(prof.extra_verbose_generic_activity("LLVM_passes", "crate"));
+            *llvm_start_time = Some(prof.verbose_generic_activity("LLVM_passes"));
         }
     }
 }
@@ -1752,7 +1743,7 @@ impl Translate for SharedEmitter {
 
 impl Emitter for SharedEmitter {
     fn emit_diagnostic(&mut self, diag: &rustc_errors::Diagnostic) {
-        let fluent_args = self.to_fluent_args(diag.args());
+        let fluent_args = to_fluent_args(diag.args());
         drop(self.sender.send(SharedEmitterMessage::Diagnostic(Diagnostic {
             msg: self.translate_messages(&diag.message, &fluent_args).to_string(),
             code: diag.code.clone(),
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index b98ff4957..84b89cd71 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -39,7 +39,7 @@ use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::Symbol;
 use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType};
-use rustc_target::abi::{Align, VariantIdx};
+use rustc_target::abi::{Align, Size, VariantIdx};
 
 use std::collections::BTreeSet;
 use std::convert::TryFrom;
@@ -151,7 +151,12 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         (&ty::Array(_, len), &ty::Slice(_)) => {
             cx.const_usize(len.eval_usize(cx.tcx(), ty::ParamEnv::reveal_all()))
         }
-        (&ty::Dynamic(ref data_a, ..), &ty::Dynamic(ref data_b, ..)) => {
+        (
+            &ty::Dynamic(ref data_a, _, src_dyn_kind),
+            &ty::Dynamic(ref data_b, _, target_dyn_kind),
+        ) => {
+            assert_eq!(src_dyn_kind, target_dyn_kind);
+
             let old_info =
                 old_info.expect("unsized_info: missing old info for trait upcasting coercion");
             if data_a.principal_def_id() == data_b.principal_def_id() {
@@ -167,11 +172,7 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             if let Some(entry_idx) = vptr_entry_idx {
                 let ptr_ty = cx.type_i8p();
                 let ptr_align = cx.tcx().data_layout.pointer_align.abi;
-                let vtable_ptr_ty = cx.scalar_pair_element_backend_type(
-                    cx.layout_of(cx.tcx().mk_mut_ptr(target)),
-                    1,
-                    true,
-                );
+                let vtable_ptr_ty = vtable_ptr_ty(cx, target, target_dyn_kind);
                 let llvtable = bx.pointercast(old_info, bx.type_ptr_to(ptr_ty));
                 let gep = bx.inbounds_gep(
                     ptr_ty,
@@ -187,18 +188,32 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 old_info
             }
         }
-        (_, &ty::Dynamic(ref data, ..)) => {
-            let vtable_ptr_ty = cx.scalar_pair_element_backend_type(
-                cx.layout_of(cx.tcx().mk_mut_ptr(target)),
-                1,
-                true,
-            );
+        (_, &ty::Dynamic(ref data, _, target_dyn_kind)) => {
+            let vtable_ptr_ty = vtable_ptr_ty(cx, target, target_dyn_kind);
             cx.const_ptrcast(meth::get_vtable(cx, source, data.principal()), vtable_ptr_ty)
         }
         _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
     }
 }
 
+// Returns the vtable pointer type of a `dyn` or `dyn*` type
+fn vtable_ptr_ty<'tcx, Cx: CodegenMethods<'tcx>>(
+    cx: &Cx,
+    target: Ty<'tcx>,
+    kind: ty::DynKind,
+) -> <Cx as BackendTypes>::Type {
+    cx.scalar_pair_element_backend_type(
+        cx.layout_of(match kind {
+            // vtable is the second field of `*mut dyn Trait`
+            ty::Dyn => cx.tcx().mk_mut_ptr(target),
+            // vtable is the second field of `dyn* Trait`
+            ty::DynStar => target,
+        }),
+        1,
+        true,
+    )
+}
+
 /// Coerces `src` to `dst_ty`. `src_ty` must be a pointer.
 pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx: &mut Bx,
@@ -248,6 +263,29 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     }
 }
 
+/// Coerces `src` to `dst_ty` which is guaranteed to be a `dyn*` type.
+pub fn cast_to_dyn_star<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
+    bx: &mut Bx,
+    src: Bx::Value,
+    src_ty_and_layout: TyAndLayout<'tcx>,
+    dst_ty: Ty<'tcx>,
+    old_info: Option<Bx::Value>,
+) -> (Bx::Value, Bx::Value) {
+    debug!("cast_to_dyn_star: {:?} => {:?}", src_ty_and_layout.ty, dst_ty);
+    assert!(
+        matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
+        "destination type must be a dyn*"
+    );
+    // FIXME(dyn-star): this is probably not the best way to check if this is
+    // a pointer, and really we should ensure that the value is a suitable
+    // pointer earlier in the compilation process.
+    let src = match src_ty_and_layout.pointee_info_at(bx.cx(), Size::ZERO) {
+        Some(_) => bx.ptrtoint(src, bx.cx().type_isize()),
+        None => bx.bitcast(src, bx.type_isize()),
+    };
+    (src, unsized_info(bx, src_ty_and_layout.ty, dst_ty, old_info))
+}
+
 /// Coerces `src`, which is a reference to a value of type `src_ty`,
 /// to a value of type `dst_ty`, and stores the result in `dst`.
 pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
@@ -299,40 +337,26 @@ pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
 pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx: &mut Bx,
-    op: hir::BinOpKind,
-    lhs: Bx::Value,
-    rhs: Bx::Value,
-) -> Bx::Value {
-    cast_shift_rhs(bx, op, lhs, rhs)
-}
-
-fn cast_shift_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
-    bx: &mut Bx,
-    op: hir::BinOpKind,
     lhs: Bx::Value,
     rhs: Bx::Value,
 ) -> Bx::Value {
     // Shifts may have any size int on the rhs
-    if op.is_shift() {
-        let mut rhs_llty = bx.cx().val_ty(rhs);
-        let mut lhs_llty = bx.cx().val_ty(lhs);
-        if bx.cx().type_kind(rhs_llty) == TypeKind::Vector {
-            rhs_llty = bx.cx().element_type(rhs_llty)
-        }
-        if bx.cx().type_kind(lhs_llty) == TypeKind::Vector {
-            lhs_llty = bx.cx().element_type(lhs_llty)
-        }
-        let rhs_sz = bx.cx().int_width(rhs_llty);
-        let lhs_sz = bx.cx().int_width(lhs_llty);
-        if lhs_sz < rhs_sz {
-            bx.trunc(rhs, lhs_llty)
-        } else if lhs_sz > rhs_sz {
-            // FIXME (#1877: If in the future shifting by negative
-            // values is no longer undefined then this is wrong.
-            bx.zext(rhs, lhs_llty)
-        } else {
-            rhs
-        }
+    let mut rhs_llty = bx.cx().val_ty(rhs);
+    let mut lhs_llty = bx.cx().val_ty(lhs);
+    if bx.cx().type_kind(rhs_llty) == TypeKind::Vector {
+        rhs_llty = bx.cx().element_type(rhs_llty)
+    }
+    if bx.cx().type_kind(lhs_llty) == TypeKind::Vector {
+        lhs_llty = bx.cx().element_type(lhs_llty)
+    }
+    let rhs_sz = bx.cx().int_width(rhs_llty);
+    let lhs_sz = bx.cx().int_width(lhs_llty);
+    if lhs_sz < rhs_sz {
+        bx.trunc(rhs, lhs_llty)
+    } else if lhs_sz > rhs_sz {
+        // FIXME (#1877: If in the future shifting by negative
+        // values is no longer undefined then this is wrong.
+        bx.zext(rhs, lhs_llty)
     } else {
         rhs
     }
@@ -475,7 +499,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             (rust_main, start_ty, vec![arg_argc, arg_argv])
         };
 
-        let result = bx.call(start_ty, start_fn, &args, None);
+        let result = bx.call(start_ty, None, start_fn, &args, None);
         let cast = bx.intcast(result, cx.type_int(), true);
         bx.ret(cast);
 
diff --git a/compiler/rustc_codegen_ssa/src/common.rs b/compiler/rustc_codegen_ssa/src/common.rs
index 8ca1a6084..71f9179d0 100644
--- a/compiler/rustc_codegen_ssa/src/common.rs
+++ b/compiler/rustc_codegen_ssa/src/common.rs
@@ -1,7 +1,6 @@
 #![allow(non_camel_case_types)]
 
 use rustc_errors::struct_span_err;
-use rustc_hir as hir;
 use rustc_hir::LangItem;
 use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::{self, layout::TyAndLayout, Ty, TyCtxt};
@@ -140,7 +139,7 @@ pub fn build_unchecked_lshift<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     lhs: Bx::Value,
     rhs: Bx::Value,
 ) -> Bx::Value {
-    let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shl, lhs, rhs);
+    let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs);
     // #1877, #10183: Ensure that input is always valid
     let rhs = shift_mask_rhs(bx, rhs);
     bx.shl(lhs, rhs)
@@ -152,7 +151,7 @@ pub fn build_unchecked_rshift<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     lhs: Bx::Value,
     rhs: Bx::Value,
 ) -> Bx::Value {
-    let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shr, lhs, rhs);
+    let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs);
     // #1877, #10183: Ensure that input is always valid
     let rhs = shift_mask_rhs(bx, rhs);
     let is_signed = lhs_t.is_signed();
diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index 135ed680d..e05646e1e 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -666,10 +666,8 @@ fn push_const_param<'tcx>(tcx: TyCtxt<'tcx>, ct: ty::Const<'tcx>, output: &mut S
                     hcx.while_hashing_spans(false, |hcx| {
                         ct.to_valtree().hash_stable(hcx, &mut hasher)
                     });
-                    // Note: Don't use `StableHashResult` impl of `u64` here directly, since that
-                    // would lead to endianness problems.
-                    let hash: u128 = hasher.finish();
-                    (hash.to_le() as u64).to_le()
+                    let hash: u64 = hasher.finish();
+                    hash
                 });
 
                 if cpp_like_debuginfo(tcx) {
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
new file mode 100644
index 000000000..ebb531f1c
--- /dev/null
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -0,0 +1,356 @@
+//! Errors emitted by codegen_ssa
+
+use crate::back::command::Command;
+use rustc_errors::{
+    fluent, DiagnosticArgValue, DiagnosticBuilder, ErrorGuaranteed, Handler, IntoDiagnostic,
+    IntoDiagnosticArg,
+};
+use rustc_macros::Diagnostic;
+use rustc_span::{Span, Symbol};
+use std::borrow::Cow;
+use std::io::Error;
+use std::path::{Path, PathBuf};
+use std::process::ExitStatus;
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_lib_def_write_failure)]
+pub struct LibDefWriteFailure {
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_version_script_write_failure)]
+pub struct VersionScriptWriteFailure {
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_symbol_file_write_failure)]
+pub struct SymbolFileWriteFailure {
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_ld64_unimplemented_modifier)]
+pub struct Ld64UnimplementedModifier;
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_linker_unsupported_modifier)]
+pub struct LinkerUnsupportedModifier;
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_L4Bender_exporting_symbols_unimplemented)]
+pub struct L4BenderExportingSymbolsUnimplemented;
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_no_natvis_directory)]
+pub struct NoNatvisDirectory {
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_copy_path_buf)]
+pub struct CopyPathBuf {
+    pub source_file: PathBuf,
+    pub output_path: PathBuf,
+    pub error: Error,
+}
+
+// Reports Paths using `Debug` implementation rather than Path's `Display` implementation.
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_copy_path)]
+pub struct CopyPath<'a> {
+    from: DebugArgPath<'a>,
+    to: DebugArgPath<'a>,
+    error: Error,
+}
+
+impl<'a> CopyPath<'a> {
+    pub fn new(from: &'a Path, to: &'a Path, error: Error) -> CopyPath<'a> {
+        CopyPath { from: DebugArgPath(from), to: DebugArgPath(to), error }
+    }
+}
+
+struct DebugArgPath<'a>(pub &'a Path);
+
+impl IntoDiagnosticArg for DebugArgPath<'_> {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Owned(format!("{:?}", self.0)))
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_ignoring_emit_path)]
+pub struct IgnoringEmitPath {
+    pub extension: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_ignoring_output)]
+pub struct IgnoringOutput {
+    pub extension: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_create_temp_dir)]
+pub struct CreateTempDir {
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_incompatible_linking_modifiers)]
+pub struct IncompatibleLinkingModifiers;
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_add_native_library)]
+pub struct AddNativeLibrary {
+    pub library_path: PathBuf,
+    pub error: Error,
+}
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_multiple_external_func_decl)]
+pub struct MultipleExternalFuncDecl<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub function: Symbol,
+    pub library_name: &'a str,
+}
+
+#[derive(Diagnostic)]
+pub enum LinkRlibError {
+    #[diag(codegen_ssa_rlib_missing_format)]
+    MissingFormat,
+
+    #[diag(codegen_ssa_rlib_only_rmeta_found)]
+    OnlyRmetaFound { crate_name: Symbol },
+
+    #[diag(codegen_ssa_rlib_not_found)]
+    NotFound { crate_name: Symbol },
+
+    #[diag(codegen_ssa_rlib_incompatible_dependency_formats)]
+    IncompatibleDependencyFormats { ty1: String, ty2: String, list1: String, list2: String },
+}
+
+pub struct ThorinErrorWrapper(pub thorin::Error);
+
+impl IntoDiagnostic<'_> for ThorinErrorWrapper {
+    fn into_diagnostic(self, handler: &Handler) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
+        let mut diag;
+        match self.0 {
+            thorin::Error::ReadInput(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_read_input_failure);
+                diag
+            }
+            thorin::Error::ParseFileKind(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_input_file_kind);
+                diag
+            }
+            thorin::Error::ParseObjectFile(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_input_object_file);
+                diag
+            }
+            thorin::Error::ParseArchiveFile(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_input_archive_file);
+                diag
+            }
+            thorin::Error::ParseArchiveMember(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_archive_member);
+                diag
+            }
+            thorin::Error::InvalidInputKind => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_invalid_input_kind);
+                diag
+            }
+            thorin::Error::DecompressData(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_decompress_data);
+                diag
+            }
+            thorin::Error::NamelessSection(_, offset) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_section_without_name);
+                diag.set_arg("offset", format!("0x{:08x}", offset));
+                diag
+            }
+            thorin::Error::RelocationWithInvalidSymbol(section, offset) => {
+                diag =
+                    handler.struct_err(fluent::codegen_ssa_thorin_relocation_with_invalid_symbol);
+                diag.set_arg("section", section);
+                diag.set_arg("offset", format!("0x{:08x}", offset));
+                diag
+            }
+            thorin::Error::MultipleRelocations(section, offset) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_multiple_relocations);
+                diag.set_arg("section", section);
+                diag.set_arg("offset", format!("0x{:08x}", offset));
+                diag
+            }
+            thorin::Error::UnsupportedRelocation(section, offset) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_unsupported_relocation);
+                diag.set_arg("section", section);
+                diag.set_arg("offset", format!("0x{:08x}", offset));
+                diag
+            }
+            thorin::Error::MissingDwoName(id) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_missing_dwo_name);
+                diag.set_arg("id", format!("0x{:08x}", id));
+                diag
+            }
+            thorin::Error::NoCompilationUnits => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_no_compilation_units);
+                diag
+            }
+            thorin::Error::NoDie => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_no_die);
+                diag
+            }
+            thorin::Error::TopLevelDieNotUnit => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_top_level_die_not_unit);
+                diag
+            }
+            thorin::Error::MissingRequiredSection(section) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_missing_required_section);
+                diag.set_arg("section", section);
+                diag
+            }
+            thorin::Error::ParseUnitAbbreviations(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_unit_abbreviations);
+                diag
+            }
+            thorin::Error::ParseUnitAttribute(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_unit_attribute);
+                diag
+            }
+            thorin::Error::ParseUnitHeader(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_unit_header);
+                diag
+            }
+            thorin::Error::ParseUnit(_) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_unit);
+                diag
+            }
+            thorin::Error::IncompatibleIndexVersion(section, format, actual) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_incompatible_index_version);
+                diag.set_arg("section", section);
+                diag.set_arg("actual", actual);
+                diag.set_arg("format", format);
+                diag
+            }
+            thorin::Error::OffsetAtIndex(_, index) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_offset_at_index);
+                diag.set_arg("index", index);
+                diag
+            }
+            thorin::Error::StrAtOffset(_, offset) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_str_at_offset);
+                diag.set_arg("offset", format!("0x{:08x}", offset));
+                diag
+            }
+            thorin::Error::ParseIndex(_, section) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_parse_index);
+                diag.set_arg("section", section);
+                diag
+            }
+            thorin::Error::UnitNotInIndex(unit) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_unit_not_in_index);
+                diag.set_arg("unit", format!("0x{:08x}", unit));
+                diag
+            }
+            thorin::Error::RowNotInIndex(_, row) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_row_not_in_index);
+                diag.set_arg("row", row);
+                diag
+            }
+            thorin::Error::SectionNotInRow => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_section_not_in_row);
+                diag
+            }
+            thorin::Error::EmptyUnit(unit) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_empty_unit);
+                diag.set_arg("unit", format!("0x{:08x}", unit));
+                diag
+            }
+            thorin::Error::MultipleDebugInfoSection => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_multiple_debug_info_section);
+                diag
+            }
+            thorin::Error::MultipleDebugTypesSection => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_multiple_debug_types_section);
+                diag
+            }
+            thorin::Error::NotSplitUnit => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_not_split_unit);
+                diag
+            }
+            thorin::Error::DuplicateUnit(unit) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_duplicate_unit);
+                diag.set_arg("unit", format!("0x{:08x}", unit));
+                diag
+            }
+            thorin::Error::MissingReferencedUnit(unit) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_missing_referenced_unit);
+                diag.set_arg("unit", format!("0x{:08x}", unit));
+                diag
+            }
+            thorin::Error::NoOutputObjectCreated => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_not_output_object_created);
+                diag
+            }
+            thorin::Error::MixedInputEncodings => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_mixed_input_encodings);
+                diag
+            }
+            thorin::Error::Io(e) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_io);
+                diag.set_arg("error", format!("{e}"));
+                diag
+            }
+            thorin::Error::ObjectRead(e) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_object_read);
+                diag.set_arg("error", format!("{e}"));
+                diag
+            }
+            thorin::Error::ObjectWrite(e) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_object_write);
+                diag.set_arg("error", format!("{e}"));
+                diag
+            }
+            thorin::Error::GimliRead(e) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_gimli_read);
+                diag.set_arg("error", format!("{e}"));
+                diag
+            }
+            thorin::Error::GimliWrite(e) => {
+                diag = handler.struct_err(fluent::codegen_ssa_thorin_gimli_write);
+                diag.set_arg("error", format!("{e}"));
+                diag
+            }
+            _ => unimplemented!("Untranslated thorin error"),
+        }
+    }
+}
+
+pub struct LinkingFailed<'a> {
+    pub linker_path: &'a PathBuf,
+    pub exit_status: ExitStatus,
+    pub command: &'a Command,
+    pub escaped_output: &'a str,
+}
+
+impl IntoDiagnostic<'_> for LinkingFailed<'_> {
+    fn into_diagnostic(self, handler: &Handler) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
+        let mut diag = handler.struct_err(fluent::codegen_ssa_linking_failed);
+        diag.set_arg("linker_path", format!("{}", self.linker_path.display()));
+        diag.set_arg("exit_status", format!("{}", self.exit_status));
+
+        diag.note(format!("{:?}", self.command)).note(self.escaped_output);
+
+        // Trying to match an error from OS linkers
+        // which by now we have no way to translate.
+        if self.escaped_output.contains("undefined reference to") {
+            diag.note(fluent::codegen_ssa_extern_funcs_not_found)
+                .note(fluent::codegen_ssa_specify_libraries_to_link)
+                .note(fluent::codegen_ssa_use_cargo_directive);
+        }
+        diag
+    }
+}
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index e736b2aba..ceebe4d41 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -1,12 +1,12 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(box_patterns)]
 #![feature(try_blocks)]
-#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(once_cell)]
 #![feature(associated_type_bounds)]
 #![feature(strict_provenance)]
 #![feature(int_roundings)]
 #![feature(if_let_guard)]
+#![feature(never_type)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]
 
@@ -44,6 +44,7 @@ pub mod base;
 pub mod common;
 pub mod coverageinfo;
 pub mod debuginfo;
+pub mod errors;
 pub mod glue;
 pub mod meth;
 pub mod mir;
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index a6b226ef7..29b7c9b0a 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -63,7 +63,9 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         }
     }
 
-    fn lltarget<Bx: BuilderMethods<'a, 'tcx>>(
+    /// Get a basic block (creating it if necessary), possibly with a landing
+    /// pad next to it.
+    fn llbb_with_landing_pad<Bx: BuilderMethods<'a, 'tcx>>(
         &self,
         fx: &mut FunctionCx<'a, 'tcx, Bx>,
         target: mir::BasicBlock,
@@ -73,32 +75,36 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         let target_funclet = fx.cleanup_kinds[target].funclet_bb(target);
         match (self.funclet_bb, target_funclet) {
             (None, None) => (lltarget, false),
-            (Some(f), Some(t_f)) if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) => {
-                (lltarget, false)
-            }
             // jump *into* cleanup - need a landing pad if GNU, cleanup pad if MSVC
             (None, Some(_)) => (fx.landing_pad_for(target), false),
             (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", self.terminator),
-            (Some(_), Some(_)) => (fx.landing_pad_for(target), true),
+            (Some(f), Some(t_f)) => {
+                if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) {
+                    (lltarget, false)
+                } else {
+                    (fx.landing_pad_for(target), true)
+                }
+            }
         }
     }
 
-    /// Create a basic block.
-    fn llblock<Bx: BuilderMethods<'a, 'tcx>>(
+    /// Get a basic block (creating it if necessary), possibly with cleanup
+    /// stuff in it or next to it.
+    fn llbb_with_cleanup<Bx: BuilderMethods<'a, 'tcx>>(
         &self,
         fx: &mut FunctionCx<'a, 'tcx, Bx>,
         target: mir::BasicBlock,
     ) -> Bx::BasicBlock {
-        let (lltarget, is_cleanupret) = self.lltarget(fx, target);
+        let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target);
         if is_cleanupret {
             // MSVC cross-funclet jump - need a trampoline
-
-            debug!("llblock: creating cleanup trampoline for {:?}", target);
+            debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess));
+            debug!("llbb_with_cleanup: creating cleanup trampoline for {:?}", target);
             let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
-            let trampoline = Bx::append_block(fx.cx, fx.llfn, name);
-            let mut trampoline_bx = Bx::build(fx.cx, trampoline);
+            let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name);
+            let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb);
             trampoline_bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
-            trampoline
+            trampoline_llbb
         } else {
             lltarget
         }
@@ -110,10 +116,11 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         bx: &mut Bx,
         target: mir::BasicBlock,
     ) {
-        let (lltarget, is_cleanupret) = self.lltarget(fx, target);
+        let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target);
         if is_cleanupret {
-            // micro-optimization: generate a `ret` rather than a jump
+            // MSVC micro-optimization: generate a `ret` rather than a jump
             // to a trampoline.
+            debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess));
             bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
         } else {
             bx.br(lltarget);
@@ -138,7 +145,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         let fn_ty = bx.fn_decl_backend_type(&fn_abi);
 
         let unwind_block = if let Some(cleanup) = cleanup.filter(|_| fn_abi.can_unwind) {
-            Some(self.llblock(fx, cleanup))
+            Some(self.llbb_with_cleanup(fx, cleanup))
         } else if fx.mir[self.bb].is_cleanup
             && fn_abi.can_unwind
             && !base::wants_msvc_seh(fx.cx.tcx().sess)
@@ -162,9 +169,15 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
             } else {
                 fx.unreachable_block()
             };
-            let invokeret =
-                bx.invoke(fn_ty, fn_ptr, &llargs, ret_llbb, unwind_block, self.funclet(fx));
-            bx.apply_attrs_callsite(&fn_abi, invokeret);
+            let invokeret = bx.invoke(
+                fn_ty,
+                Some(&fn_abi),
+                fn_ptr,
+                &llargs,
+                ret_llbb,
+                unwind_block,
+                self.funclet(fx),
+            );
             if fx.mir[self.bb].is_cleanup {
                 bx.do_not_inline(invokeret);
             }
@@ -178,8 +191,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
                 fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
             }
         } else {
-            let llret = bx.call(fn_ty, fn_ptr, &llargs, self.funclet(fx));
-            bx.apply_attrs_callsite(&fn_abi, llret);
+            let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &llargs, self.funclet(fx));
             if fx.mir[self.bb].is_cleanup {
                 // Cleanup is always the cold path. Don't inline
                 // drop glue. Also, when there is a deeply-nested
@@ -226,7 +238,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
                 options,
                 line_spans,
                 instance,
-                Some((ret_llbb, self.llblock(fx, cleanup), self.funclet(fx))),
+                Some((ret_llbb, self.llbb_with_cleanup(fx, cleanup), self.funclet(fx))),
             );
         } else {
             bx.codegen_inline_asm(template, &operands, options, line_spans, instance, None);
@@ -276,8 +288,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         if target_iter.len() == 1 {
             // If there are two targets (one conditional, one fallback), emit br instead of switch
             let (test_value, target) = target_iter.next().unwrap();
-            let lltrue = helper.llblock(self, target);
-            let llfalse = helper.llblock(self, targets.otherwise());
+            let lltrue = helper.llbb_with_cleanup(self, target);
+            let llfalse = helper.llbb_with_cleanup(self, targets.otherwise());
             if switch_ty == bx.tcx().types.bool {
                 // Don't generate trivial icmps when switching on bool
                 match test_value {
@@ -294,8 +306,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         } else {
             bx.switch(
                 discr.immediate(),
-                helper.llblock(self, targets.otherwise()),
-                target_iter.map(|(value, target)| (value, helper.llblock(self, target))),
+                helper.llbb_with_cleanup(self, targets.otherwise()),
+                target_iter.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
             );
         }
     }
@@ -525,7 +537,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let cond = bx.expect(cond, expected);
 
         // Create the failure block and the conditional branch to it.
-        let lltarget = helper.llblock(self, target);
+        let lltarget = helper.llbb_with_cleanup(self, target);
         let panic_block = bx.append_sibling_block("panic");
         if expected {
             bx.cond_br(cond, lltarget, panic_block);
@@ -1454,20 +1466,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 //          bar();
                 //      }
                 Some(&mir::TerminatorKind::Abort) => {
-                    let cs_bb =
+                    let cs_llbb =
                         Bx::append_block(self.cx, self.llfn, &format!("cs_funclet{:?}", bb));
-                    let cp_bb =
+                    let cp_llbb =
                         Bx::append_block(self.cx, self.llfn, &format!("cp_funclet{:?}", bb));
-                    ret_llbb = cs_bb;
+                    ret_llbb = cs_llbb;
 
-                    let mut cs_bx = Bx::build(self.cx, cs_bb);
-                    let cs = cs_bx.catch_switch(None, None, &[cp_bb]);
+                    let mut cs_bx = Bx::build(self.cx, cs_llbb);
+                    let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
 
                     // The "null" here is actually a RTTI type descriptor for the
                     // C++ personality function, but `catch (...)` has no type so
                     // it's null. The 64 here is actually a bitfield which
                     // represents that this is a catch-all block.
-                    let mut cp_bx = Bx::build(self.cx, cp_bb);
+                    let mut cp_bx = Bx::build(self.cx, cp_llbb);
                     let null = cp_bx.const_null(
                         cp_bx.type_i8p_ext(cp_bx.cx().data_layout().instruction_address_space),
                     );
@@ -1476,10 +1488,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     cp_bx.br(llbb);
                 }
                 _ => {
-                    let cleanup_bb =
+                    let cleanup_llbb =
                         Bx::append_block(self.cx, self.llfn, &format!("funclet_{:?}", bb));
-                    ret_llbb = cleanup_bb;
-                    let mut cleanup_bx = Bx::build(self.cx, cleanup_bb);
+                    ret_llbb = cleanup_llbb;
+                    let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
                     funclet = cleanup_bx.cleanup_pad(None, &[]);
                     cleanup_bx.br(llbb);
                 }
@@ -1487,19 +1499,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             self.funclets[bb] = Some(funclet);
             ret_llbb
         } else {
-            let bb = Bx::append_block(self.cx, self.llfn, "cleanup");
-            let mut bx = Bx::build(self.cx, bb);
+            let cleanup_llbb = Bx::append_block(self.cx, self.llfn, "cleanup");
+            let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
 
             let llpersonality = self.cx.eh_personality();
             let llretty = self.landing_pad_type();
-            let lp = bx.cleanup_landing_pad(llretty, llpersonality);
+            let lp = cleanup_bx.cleanup_landing_pad(llretty, llpersonality);
 
-            let slot = self.get_personality_slot(&mut bx);
-            slot.storage_live(&mut bx);
-            Pair(bx.extract_value(lp, 0), bx.extract_value(lp, 1)).store(&mut bx, slot);
+            let slot = self.get_personality_slot(&mut cleanup_bx);
+            slot.storage_live(&mut cleanup_bx);
+            Pair(cleanup_bx.extract_value(lp, 0), cleanup_bx.extract_value(lp, 1))
+                .store(&mut cleanup_bx, slot);
 
-            bx.br(llbb);
-            bx.llbb()
+            cleanup_bx.br(llbb);
+            cleanup_llbb
         }
     }
 
@@ -1533,8 +1546,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, LangItem::PanicNoUnwind);
             let fn_ty = bx.fn_decl_backend_type(&fn_abi);
 
-            let llret = bx.call(fn_ty, fn_ptr, &[], None);
-            bx.apply_attrs_callsite(&fn_abi, llret);
+            let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &[], None);
             bx.do_not_inline(llret);
 
             bx.unreachable();
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 2b931bfc9..da9aaf00e 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -148,10 +148,10 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     let debug_context = cx.create_function_debug_context(instance, &fn_abi, llfn, &mir);
 
     let start_llbb = Bx::append_block(cx, llfn, "start");
-    let mut bx = Bx::build(cx, start_llbb);
+    let mut start_bx = Bx::build(cx, start_llbb);
 
     if mir.basic_blocks.iter().any(|bb| bb.is_cleanup) {
-        bx.set_personality_fn(cx.eh_personality());
+        start_bx.set_personality_fn(cx.eh_personality());
     }
 
     let cleanup_kinds = analyze::cleanup_kinds(&mir);
@@ -180,7 +180,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         caller_location: None,
     };
 
-    fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut bx);
+    fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut start_bx);
 
     // Evaluate all required consts; codegen later assumes that CTFE will never fail.
     let mut all_consts_ok = true;
@@ -206,29 +206,29 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
     // Allocate variable and temp allocas
     fx.locals = {
-        let args = arg_local_refs(&mut bx, &mut fx, &memory_locals);
+        let args = arg_local_refs(&mut start_bx, &mut fx, &memory_locals);
 
         let mut allocate_local = |local| {
             let decl = &mir.local_decls[local];
-            let layout = bx.layout_of(fx.monomorphize(decl.ty));
+            let layout = start_bx.layout_of(fx.monomorphize(decl.ty));
             assert!(!layout.ty.has_erasable_regions());
 
             if local == mir::RETURN_PLACE && fx.fn_abi.ret.is_indirect() {
                 debug!("alloc: {:?} (return place) -> place", local);
-                let llretptr = bx.get_param(0);
+                let llretptr = start_bx.get_param(0);
                 return LocalRef::Place(PlaceRef::new_sized(llretptr, layout));
             }
 
             if memory_locals.contains(local) {
                 debug!("alloc: {:?} -> place", local);
                 if layout.is_unsized() {
-                    LocalRef::UnsizedPlace(PlaceRef::alloca_unsized_indirect(&mut bx, layout))
+                    LocalRef::UnsizedPlace(PlaceRef::alloca_unsized_indirect(&mut start_bx, layout))
                 } else {
-                    LocalRef::Place(PlaceRef::alloca(&mut bx, layout))
+                    LocalRef::Place(PlaceRef::alloca(&mut start_bx, layout))
                 }
             } else {
                 debug!("alloc: {:?} -> operand", local);
-                LocalRef::new_operand(&mut bx, layout)
+                LocalRef::new_operand(&mut start_bx, layout)
             }
         };
 
@@ -240,7 +240,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     };
 
     // Apply debuginfo to the newly allocated locals.
-    fx.debug_introduce_locals(&mut bx);
+    fx.debug_introduce_locals(&mut start_bx);
 
     // Codegen the body of each block using reverse postorder
     for (bb, _) in traversal::reverse_postorder(&mir) {
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index 37b1e0362..e6ba642a7 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -352,7 +352,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
 
         // Allocate an appropriate region on the stack, and copy the value into it
         let (llsize, _) = glue::size_and_align_of_dst(bx, unsized_ty, Some(llextra));
-        let lldst = bx.array_alloca(bx.cx().type_i8(), llsize, max_align);
+        let lldst = bx.byte_array_alloca(llsize, max_align);
         bx.memcpy(lldst, max_align, llptr, min_align, llsize, flags);
 
         // Store the allocated region and the extra to the indirect place.
diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs
index 13d8f6edd..9c18df564 100644
--- a/compiler/rustc_codegen_ssa/src/mir/place.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/place.rs
@@ -400,6 +400,21 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
         downcast
     }
 
+    pub fn project_type<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
+        &self,
+        bx: &mut Bx,
+        ty: Ty<'tcx>,
+    ) -> Self {
+        let mut downcast = *self;
+        downcast.layout = bx.cx().layout_of(ty);
+
+        // Cast to the appropriate type.
+        let variant_ty = bx.cx().backend_type(downcast.layout);
+        downcast.llval = bx.pointercast(downcast.llval, bx.cx().type_ptr_to(variant_ty));
+
+        downcast
+    }
+
     pub fn storage_live<Bx: BuilderMethods<'a, 'tcx, Value = V>>(&self, bx: &mut Bx) {
         bx.lifetime_start(self.llval, self.layout.size);
     }
@@ -442,6 +457,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 mir::ProjectionElem::Field(ref field, _) => {
                     cg_base.project_field(bx, field.index())
                 }
+                mir::ProjectionElem::OpaqueCast(ty) => cg_base.project_type(bx, ty),
                 mir::ProjectionElem::Index(index) => {
                     let index = &mir::Operand::Copy(mir::Place::from(index));
                     let index = self.codegen_operand(bx, index);
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index 56852b0fc..4aab31fbf 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -4,7 +4,6 @@ use super::{FunctionCx, LocalRef};
 
 use crate::base;
 use crate::common::{self, IntPredicate};
-use crate::meth::get_vtable;
 use crate::traits::*;
 use crate::MemFlags;
 
@@ -250,7 +249,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         OperandValue::Pair(lldata, llextra)
                     }
                     mir::CastKind::Pointer(PointerCast::MutToConstPointer)
-                    | mir::CastKind::Misc
+                    | mir::CastKind::PtrToPtr
                         if bx.cx().is_backend_scalar_pair(operand.layout) =>
                     {
                         if let OperandValue::Pair(data_ptr, meta) = operand.val {
@@ -273,24 +272,25 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         }
                     }
                     mir::CastKind::DynStar => {
-                        let data = match operand.val {
+                        let (lldata, llextra) = match operand.val {
                             OperandValue::Ref(_, _, _) => todo!(),
-                            OperandValue::Immediate(v) => v,
-                            OperandValue::Pair(_, _) => todo!(),
+                            OperandValue::Immediate(v) => (v, None),
+                            OperandValue::Pair(v, l) => (v, Some(l)),
                         };
-                        let trait_ref =
-                            if let ty::Dynamic(data, _, ty::DynStar) = cast.ty.kind() {
-                                data.principal()
-                            } else {
-                                bug!("Only valid to do a DynStar cast into a DynStar type")
-                            };
-                        let vtable = get_vtable(bx.cx(), source.ty(self.mir, bx.tcx()), trait_ref);
-                        OperandValue::Pair(data, vtable)
+                        let (lldata, llextra) =
+                            base::cast_to_dyn_star(&mut bx, lldata, operand.layout, cast.ty, llextra);
+                        OperandValue::Pair(lldata, llextra)
                     }
                     mir::CastKind::Pointer(
                         PointerCast::MutToConstPointer | PointerCast::ArrayToPointer,
                     )
-                    | mir::CastKind::Misc
+                    | mir::CastKind::IntToInt
+                    | mir::CastKind::FloatToInt
+                    | mir::CastKind::FloatToFloat
+                    | mir::CastKind::IntToFloat
+                    | mir::CastKind::PtrToPtr
+                    | mir::CastKind::FnPtrToPtr
+
                     // Since int2ptr can have arbitrary integer types as input (so we have to do
                     // sign extension and all that), it is currently best handled in the same code
                     // path as the other integer-to-X casts.
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index 0e259bcd1..83407ee8f 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -13,17 +13,25 @@ pub const RUSTC_SPECIFIC_FEATURES: &[&str] = &["crt-static"];
 // if it doesn't, to_llvm_feature in llvm_util in rustc_codegen_llvm needs to be adapted
 
 const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    // tidy-alphabetical-start
     ("aclass", Some(sym::arm_target_feature)),
-    ("mclass", Some(sym::arm_target_feature)),
-    ("rclass", Some(sym::arm_target_feature)),
-    ("dsp", Some(sym::arm_target_feature)),
-    ("neon", Some(sym::arm_target_feature)),
+    ("aes", Some(sym::arm_target_feature)),
     ("crc", Some(sym::arm_target_feature)),
     ("crypto", Some(sym::arm_target_feature)),
-    ("aes", Some(sym::arm_target_feature)),
-    ("sha2", Some(sym::arm_target_feature)),
-    ("i8mm", Some(sym::arm_target_feature)),
+    ("d32", Some(sym::arm_target_feature)),
     ("dotprod", Some(sym::arm_target_feature)),
+    ("dsp", Some(sym::arm_target_feature)),
+    ("fp-armv8", Some(sym::arm_target_feature)),
+    ("i8mm", Some(sym::arm_target_feature)),
+    ("mclass", Some(sym::arm_target_feature)),
+    ("neon", Some(sym::arm_target_feature)),
+    ("rclass", Some(sym::arm_target_feature)),
+    ("sha2", Some(sym::arm_target_feature)),
+    // This is needed for inline assembly, but shouldn't be stabilized as-is
+    // since it should be enabled per-function using #[instruction_set], not
+    // #[target_feature].
+    ("thumb-mode", Some(sym::arm_target_feature)),
+    ("thumb2", Some(sym::arm_target_feature)),
     ("v5te", Some(sym::arm_target_feature)),
     ("v6", Some(sym::arm_target_feature)),
     ("v6k", Some(sym::arm_target_feature)),
@@ -33,104 +41,97 @@ const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("vfp2", Some(sym::arm_target_feature)),
     ("vfp3", Some(sym::arm_target_feature)),
     ("vfp4", Some(sym::arm_target_feature)),
-    ("fp-armv8", Some(sym::arm_target_feature)),
-    // This is needed for inline assembly, but shouldn't be stabilized as-is
-    // since it should be enabled per-function using #[instruction_set], not
-    // #[target_feature].
-    ("thumb-mode", Some(sym::arm_target_feature)),
-    ("thumb2", Some(sym::arm_target_feature)),
-    ("d32", Some(sym::arm_target_feature)),
+    // tidy-alphabetical-end
 ];
 
 const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    // FEAT_AdvSimd & FEAT_FP
-    ("neon", None),
-    // FEAT_FP16
-    ("fp16", None),
-    // FEAT_SVE
-    ("sve", None),
+    // tidy-alphabetical-start
+    // FEAT_AES
+    ("aes", None),
+    // FEAT_BF16
+    ("bf16", None),
+    // FEAT_BTI
+    ("bti", None),
     // FEAT_CRC
     ("crc", None),
-    // FEAT_RAS
-    ("ras", None),
-    // FEAT_LSE
-    ("lse", None),
-    // FEAT_RDM
-    ("rdm", None),
-    // FEAT_RCPC
-    ("rcpc", None),
-    // FEAT_RCPC2
-    ("rcpc2", None),
-    // FEAT_DotProd
-    ("dotprod", None),
-    // FEAT_TME
-    ("tme", None),
-    // FEAT_FHM
-    ("fhm", None),
     // FEAT_DIT
     ("dit", None),
-    // FEAT_FLAGM
-    ("flagm", None),
-    // FEAT_SSBS
-    ("ssbs", None),
-    // FEAT_SB
-    ("sb", None),
-    // FEAT_PAUTH (address authentication)
-    ("paca", None),
-    // FEAT_PAUTH (generic authentication)
-    ("pacg", None),
+    // FEAT_DotProd
+    ("dotprod", None),
     // FEAT_DPB
     ("dpb", None),
     // FEAT_DPB2
     ("dpb2", None),
-    // FEAT_SVE2
-    ("sve2", None),
-    // FEAT_SVE2_AES
-    ("sve2-aes", None),
-    // FEAT_SVE2_SM4
-    ("sve2-sm4", None),
-    // FEAT_SVE2_SHA3
-    ("sve2-sha3", None),
-    // FEAT_SVE2_BitPerm
-    ("sve2-bitperm", None),
-    // FEAT_FRINTTS
-    ("frintts", None),
-    // FEAT_I8MM
-    ("i8mm", None),
     // FEAT_F32MM
     ("f32mm", None),
     // FEAT_F64MM
     ("f64mm", None),
-    // FEAT_BF16
-    ("bf16", None),
-    // FEAT_RAND
-    ("rand", None),
-    // FEAT_BTI
-    ("bti", None),
-    // FEAT_MTE
-    ("mte", None),
-    // FEAT_JSCVT
-    ("jsconv", None),
     // FEAT_FCMA
     ("fcma", None),
-    // FEAT_AES
-    ("aes", None),
+    // FEAT_FHM
+    ("fhm", None),
+    // FEAT_FLAGM
+    ("flagm", None),
+    // FEAT_FP16
+    ("fp16", None),
+    // FEAT_FRINTTS
+    ("frintts", None),
+    // FEAT_I8MM
+    ("i8mm", None),
+    // FEAT_JSCVT
+    ("jsconv", None),
+    // FEAT_LOR
+    ("lor", None),
+    // FEAT_LSE
+    ("lse", None),
+    // FEAT_MTE
+    ("mte", None),
+    // FEAT_AdvSimd & FEAT_FP
+    ("neon", None),
+    // FEAT_PAUTH (address authentication)
+    ("paca", None),
+    // FEAT_PAUTH (generic authentication)
+    ("pacg", None),
+    // FEAT_PAN
+    ("pan", None),
+    // FEAT_PMUv3
+    ("pmuv3", None),
+    // FEAT_RAND
+    ("rand", None),
+    // FEAT_RAS
+    ("ras", None),
+    // FEAT_RCPC
+    ("rcpc", None),
+    // FEAT_RCPC2
+    ("rcpc2", None),
+    // FEAT_RDM
+    ("rdm", None),
+    // FEAT_SB
+    ("sb", None),
     // FEAT_SHA1 & FEAT_SHA256
     ("sha2", None),
     // FEAT_SHA512 & FEAT_SHA3
     ("sha3", None),
     // FEAT_SM3 & FEAT_SM4
     ("sm4", None),
-    // FEAT_PAN
-    ("pan", None),
-    // FEAT_LOR
-    ("lor", None),
-    // FEAT_VHE
-    ("vh", None),
-    // FEAT_PMUv3
-    ("pmuv3", None),
     // FEAT_SPE
     ("spe", None),
+    // FEAT_SSBS
+    ("ssbs", None),
+    // FEAT_SVE
+    ("sve", None),
+    // FEAT_SVE2
+    ("sve2", None),
+    // FEAT_SVE2_AES
+    ("sve2-aes", None),
+    // FEAT_SVE2_BitPerm
+    ("sve2-bitperm", None),
+    // FEAT_SVE2_SHA3
+    ("sve2-sha3", None),
+    // FEAT_SVE2_SM4
+    ("sve2-sm4", None),
+    // FEAT_TME
+    ("tme", None),
     ("v8.1a", Some(sym::aarch64_ver_target_feature)),
     ("v8.2a", Some(sym::aarch64_ver_target_feature)),
     ("v8.3a", Some(sym::aarch64_ver_target_feature)),
@@ -138,6 +139,9 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("v8.5a", Some(sym::aarch64_ver_target_feature)),
     ("v8.6a", Some(sym::aarch64_ver_target_feature)),
     ("v8.7a", Some(sym::aarch64_ver_target_feature)),
+    // FEAT_VHE
+    ("vh", None),
+    // tidy-alphabetical-end
 ];
 
 const AARCH64_TIED_FEATURES: &[&[&str]] = &[
@@ -145,6 +149,7 @@ const AARCH64_TIED_FEATURES: &[&[&str]] = &[
 ];
 
 const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    // tidy-alphabetical-start
     ("adx", None),
     ("aes", None),
     ("avx", None),
@@ -194,69 +199,80 @@ const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("xsavec", None),
     ("xsaveopt", None),
     ("xsaves", None),
+    // tidy-alphabetical-end
 ];
 
 const HEXAGON_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    // tidy-alphabetical-start
     ("hvx", Some(sym::hexagon_target_feature)),
     ("hvx-length128b", Some(sym::hexagon_target_feature)),
+    // tidy-alphabetical-end
 ];
 
 const POWERPC_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    // tidy-alphabetical-start
     ("altivec", Some(sym::powerpc_target_feature)),
     ("power8-altivec", Some(sym::powerpc_target_feature)),
-    ("power9-altivec", Some(sym::powerpc_target_feature)),
     ("power8-vector", Some(sym::powerpc_target_feature)),
+    ("power9-altivec", Some(sym::powerpc_target_feature)),
     ("power9-vector", Some(sym::powerpc_target_feature)),
     ("vsx", Some(sym::powerpc_target_feature)),
+    // tidy-alphabetical-end
 ];
 
 const MIPS_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    // tidy-alphabetical-start
     ("fp64", Some(sym::mips_target_feature)),
     ("msa", Some(sym::mips_target_feature)),
     ("virt", Some(sym::mips_target_feature)),
+    // tidy-alphabetical-end
 ];
 
 const RISCV_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    ("m", Some(sym::riscv_target_feature)),
+    // tidy-alphabetical-start
     ("a", Some(sym::riscv_target_feature)),
     ("c", Some(sym::riscv_target_feature)),
-    ("f", Some(sym::riscv_target_feature)),
     ("d", Some(sym::riscv_target_feature)),
     ("e", Some(sym::riscv_target_feature)),
+    ("f", Some(sym::riscv_target_feature)),
+    ("m", Some(sym::riscv_target_feature)),
     ("v", Some(sym::riscv_target_feature)),
-    ("zfinx", Some(sym::riscv_target_feature)),
-    ("zdinx", Some(sym::riscv_target_feature)),
-    ("zhinx", Some(sym::riscv_target_feature)),
-    ("zhinxmin", Some(sym::riscv_target_feature)),
-    ("zfh", Some(sym::riscv_target_feature)),
-    ("zfhmin", Some(sym::riscv_target_feature)),
     ("zba", Some(sym::riscv_target_feature)),
     ("zbb", Some(sym::riscv_target_feature)),
     ("zbc", Some(sym::riscv_target_feature)),
-    ("zbs", Some(sym::riscv_target_feature)),
     ("zbkb", Some(sym::riscv_target_feature)),
     ("zbkc", Some(sym::riscv_target_feature)),
     ("zbkx", Some(sym::riscv_target_feature)),
+    ("zbs", Some(sym::riscv_target_feature)),
+    ("zdinx", Some(sym::riscv_target_feature)),
+    ("zfh", Some(sym::riscv_target_feature)),
+    ("zfhmin", Some(sym::riscv_target_feature)),
+    ("zfinx", Some(sym::riscv_target_feature)),
+    ("zhinx", Some(sym::riscv_target_feature)),
+    ("zhinxmin", Some(sym::riscv_target_feature)),
+    ("zk", Some(sym::riscv_target_feature)),
+    ("zkn", Some(sym::riscv_target_feature)),
     ("zknd", Some(sym::riscv_target_feature)),
     ("zkne", Some(sym::riscv_target_feature)),
     ("zknh", Some(sym::riscv_target_feature)),
-    ("zksed", Some(sym::riscv_target_feature)),
-    ("zksh", Some(sym::riscv_target_feature)),
     ("zkr", Some(sym::riscv_target_feature)),
-    ("zkn", Some(sym::riscv_target_feature)),
     ("zks", Some(sym::riscv_target_feature)),
-    ("zk", Some(sym::riscv_target_feature)),
+    ("zksed", Some(sym::riscv_target_feature)),
+    ("zksh", Some(sym::riscv_target_feature)),
     ("zkt", Some(sym::riscv_target_feature)),
+    // tidy-alphabetical-end
 ];
 
 const WASM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    ("simd128", None),
+    // tidy-alphabetical-start
     ("atomics", Some(sym::wasm_target_feature)),
-    ("nontrapping-fptoint", Some(sym::wasm_target_feature)),
     ("bulk-memory", Some(sym::wasm_target_feature)),
     ("mutable-globals", Some(sym::wasm_target_feature)),
+    ("nontrapping-fptoint", Some(sym::wasm_target_feature)),
     ("reference-types", Some(sym::wasm_target_feature)),
     ("sign-ext", Some(sym::wasm_target_feature)),
+    ("simd128", None),
+    // tidy-alphabetical-end
 ];
 
 const BPF_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[("alu32", Some(sym::bpf_target_feature))];
diff --git a/compiler/rustc_codegen_ssa/src/traits/abi.rs b/compiler/rustc_codegen_ssa/src/traits/abi.rs
index a00d78daf..60d8f2a9e 100644
--- a/compiler/rustc_codegen_ssa/src/traits/abi.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/abi.rs
@@ -1,8 +1,5 @@
 use super::BackendTypes;
-use rustc_middle::ty::Ty;
-use rustc_target::abi::call::FnAbi;
 
 pub trait AbiBuilderMethods<'tcx>: BackendTypes {
-    fn apply_attrs_callsite(&mut self, fn_abi: &FnAbi<'tcx, Ty<'tcx>>, callsite: Self::Value);
     fn get_param(&mut self, index: usize) -> Self::Value;
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index 779bd3ea2..87e347c61 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -134,8 +134,6 @@ pub trait ExtraBackendMethods: CodegenBackend + WriteBackendMethods + Sized + Se
         opt_level: config::OptLevel,
         target_features: &[String],
     ) -> TargetMachineFactoryFn<Self>;
-    fn target_cpu<'b>(&self, sess: &'b Session) -> &'b str;
-    fn tune_cpu<'b>(&self, sess: &'b Session) -> Option<&'b str>;
 
     fn spawn_thread<F, T>(_time_trace: bool, f: F) -> std::thread::JoinHandle<T>
     where
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 10cf8948b..01408f39f 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -17,6 +17,7 @@ use crate::MemFlags;
 use rustc_middle::ty::layout::{HasParamEnv, TyAndLayout};
 use rustc_middle::ty::Ty;
 use rustc_span::Span;
+use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::{Abi, Align, Scalar, Size, WrappingRange};
 use rustc_target::spec::HasTargetSpec;
 
@@ -71,6 +72,7 @@ pub trait BuilderMethods<'a, 'tcx>:
     fn invoke(
         &mut self,
         llty: Self::Type,
+        fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
         llfn: Self::Value,
         args: &[Self::Value],
         then: Self::BasicBlock,
@@ -133,8 +135,7 @@ pub trait BuilderMethods<'a, 'tcx>:
     fn to_immediate_scalar(&mut self, val: Self::Value, scalar: Scalar) -> Self::Value;
 
     fn alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
-    fn dynamic_alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
-    fn array_alloca(&mut self, ty: Self::Type, len: Self::Value, align: Align) -> Self::Value;
+    fn byte_array_alloca(&mut self, len: Self::Value, align: Align) -> Self::Value;
 
     fn load(&mut self, ty: Self::Type, ptr: Self::Value, align: Align) -> Self::Value;
     fn volatile_load(&mut self, ty: Self::Type, ptr: Self::Value) -> Self::Value;
@@ -320,6 +321,7 @@ pub trait BuilderMethods<'a, 'tcx>:
     fn call(
         &mut self,
         llty: Self::Type,
+        fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
         llfn: Self::Value,
         args: &[Self::Value],
         funclet: Option<&Self::Funclet>,
diff --git a/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs b/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
index 7755e6793..450672fb9 100644
--- a/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
@@ -5,7 +5,7 @@ use rustc_span::Span;
 use rustc_target::abi::call::FnAbi;
 
 pub trait IntrinsicCallMethods<'tcx>: BackendTypes {
-    /// Remember to add all intrinsics here, in `compiler/rustc_typeck/src/check/mod.rs`,
+    /// Remember to add all intrinsics here, in `compiler/rustc_hir_analysis/src/check/mod.rs`,
     /// and in `library/core/src/intrinsics.rs`; if you need access to any LLVM intrinsics,
     /// add them to `compiler/rustc_codegen_llvm/src/context.rs`.
     fn codegen_intrinsic_call(
diff --git a/compiler/rustc_codegen_ssa/src/traits/misc.rs b/compiler/rustc_codegen_ssa/src/traits/misc.rs
index 4266e42ec..04e2b8796 100644
--- a/compiler/rustc_codegen_ssa/src/traits/misc.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/misc.rs
@@ -15,12 +15,8 @@ pub trait MiscMethods<'tcx>: BackendTypes {
     fn eh_personality(&self) -> Self::Value;
     fn sess(&self) -> &Session;
     fn codegen_unit(&self) -> &'tcx CodegenUnit<'tcx>;
-    fn used_statics(&self) -> &RefCell<Vec<Self::Value>>;
-    fn compiler_used_statics(&self) -> &RefCell<Vec<Self::Value>>;
     fn set_frame_pointer_type(&self, llfn: Self::Function);
     fn apply_target_cpu_attr(&self, llfn: Self::Function);
-    fn create_used_variable(&self);
-    fn create_compiler_used_variable(&self);
     /// Declares the extern "C" main function for the entry point. Returns None if the symbol already exists.
     fn declare_c_main(&self, fn_type: Self::Type) -> Option<Self::Function>;
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/type_.rs b/compiler/rustc_codegen_ssa/src/traits/type_.rs
index 8158e8dd0..bdc6a91cf 100644
--- a/compiler/rustc_codegen_ssa/src/traits/type_.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/type_.rs
@@ -5,7 +5,6 @@ use crate::common::TypeKind;
 use crate::mir::place::PlaceRef;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::ty::{self, Ty};
-use rustc_span::DUMMY_SP;
 use rustc_target::abi::call::{ArgAbi, CastTarget, FnAbi, Reg};
 use rustc_target::abi::{AddressSpace, Integer};
 
@@ -75,16 +74,16 @@ pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
     }
 
     fn type_is_sized(&self, ty: Ty<'tcx>) -> bool {
-        ty.is_sized(self.tcx().at(DUMMY_SP), ty::ParamEnv::reveal_all())
+        ty.is_sized(self.tcx(), ty::ParamEnv::reveal_all())
     }
 
     fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool {
-        ty.is_freeze(self.tcx().at(DUMMY_SP), ty::ParamEnv::reveal_all())
+        ty.is_freeze(self.tcx(), ty::ParamEnv::reveal_all())
     }
 
     fn type_has_metadata(&self, ty: Ty<'tcx>) -> bool {
         let param_env = ty::ParamEnv::reveal_all();
-        if ty.is_sized(self.tcx().at(DUMMY_SP), param_env) {
+        if ty.is_sized(self.tcx(), param_env) {
             return false;
         }
 
diff --git a/compiler/rustc_codegen_ssa/src/traits/write.rs b/compiler/rustc_codegen_ssa/src/traits/write.rs
index e54ec34f1..e0e8ffa89 100644
--- a/compiler/rustc_codegen_ssa/src/traits/write.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/write.rs
@@ -9,7 +9,6 @@ pub trait WriteBackendMethods: 'static + Sized + Clone {
     type Module: Send + Sync;
     type TargetMachine;
     type ModuleBuffer: ModuleBufferMethods;
-    type Context: ?Sized;
     type ThinData: Send + Sync;
     type ThinBuffer: ThinBufferMethods;