Auto merge of #119945 - matthiaskrgr:rollup-oy3e1j2, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #119189 (Move section "Installing from Source" to seperate file)
 - #119925 (store the segment name when resolution fails)
 - #119935 (Move personality implementation out of PAL)
 - #119937 (Improve UEFI target docs)
 - #119938 (Allow unauthorized users to user the has-merge-commits label)

r? `@ghost`
`@rustbot` modify labels: rollup

.reuse/dep5

@@ -18,6 +18,7 @@ Files: compiler/*
        configure
        CONTRIBUTING.md
        COPYRIGHT
+       INSTALL.md
        LICENSE-APACHE
        LICENSE-MIT
        README.md

INSTALL.md

@@ -0,0 +1,253 @@
+# Installing from Source
+
+**Note: This document describes _building_ Rust _from source_.
+This is _not recommended_ if you don't know what you're doing.
+If you just want to install Rust, check out the [README.md](README.md) instead.**
+
+The Rust build system uses a Python script called `x.py` to build the compiler,
+which manages the bootstrapping process. It lives at the root of the project.
+It also uses a file named `config.toml` to determine various configuration
+settings for the build. You can see a full list of options in
+`config.example.toml`.
+
+The `x.py` command can be run directly on most Unix systems in the following
+format:
+
+```sh
+./x.py <subcommand> [flags]
+```
+
+This is how the documentation and examples assume you are running `x.py`.
+See the [rustc dev guide][rustcguidebuild] if this does not work on your
+platform.
+
+More information about `x.py` can be found by running it with the `--help` flag
+or reading the [rustc dev guide][rustcguidebuild].
+
+[gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.html
+[rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#what-is-xpy
+
+## Dependencies
+
+Make sure you have installed the dependencies:
+
+* `python` 3 or 2.7
+* `git`
+* A C compiler (when building for the host, `cc` is enough; cross-compiling may
+  need additional compilers)
+* `curl` (not needed on Windows)
+* `pkg-config` if you are compiling on Linux and targeting Linux
+* `libiconv` (already included with glibc on Debian-based distros)
+
+To build Cargo, you'll also need OpenSSL (`libssl-dev` or `openssl-devel` on
+most Unix distros).
+
+If building LLVM from source, you'll need additional tools:
+
+* `g++`, `clang++`, or MSVC with versions listed on
+  [LLVM's documentation](https://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library)
+* `ninja`, or GNU `make` 3.81 or later (Ninja is recommended, especially on
+  Windows)
+* `cmake` 3.13.4 or later
+* `libstdc++-static` may be required on some Linux distributions such as Fedora
+  and Ubuntu
+
+On tier 1 or tier 2 with host tools platforms, you can also choose to download
+LLVM by setting `llvm.download-ci-llvm = true`.
+Otherwise, you'll need LLVM installed and `llvm-config` in your path.
+See [the rustc-dev-guide for more info][sysllvm].
+
+[sysllvm]: https://rustc-dev-guide.rust-lang.org/building/new-target.html#using-pre-built-llvm
+
+
+## Building on a Unix-like system
+
+### Build steps
+
+1. Clone the [source] with `git`:
+
+   ```sh
+   git clone https://github.com/rust-lang/rust.git
+   cd rust
+   ```
+
+[source]: https://github.com/rust-lang/rust
+
+2. Configure the build settings:
+
+   ```sh
+   ./configure
+   ```
+
+   If you plan to use `x.py install` to create an installation, it is
+   recommended that you set the `prefix` value in the `[install]` section to a
+   directory: `./configure --set install.prefix=<path>`
+
+3. Build and install:
+
+   ```sh
+   ./x.py build && ./x.py install
+   ```
+
+   When complete, `./x.py install` will place several programs into
+   `$PREFIX/bin`: `rustc`, the Rust compiler, and `rustdoc`, the
+   API-documentation tool. By default, it will also include [Cargo], Rust's
+   package manager. You can disable this behavior by passing
+   `--set build.extended=false` to `./configure`.
+
+[Cargo]: https://github.com/rust-lang/cargo
+
+### Configure and Make
+
+This project provides a configure script and makefile (the latter of which just
+invokes `x.py`). `./configure` is the recommended way to programmatically
+generate a `config.toml`. `make` is not recommended (we suggest using `x.py`
+directly), but it is supported and we try not to break it unnecessarily.
+
+```sh
+./configure
+make && sudo make install
+```
+
+`configure` generates a `config.toml` which can also be used with normal `x.py`
+invocations.
+
+## Building on Windows
+
+On Windows, we suggest using [winget] to install dependencies by running the
+following in a terminal:
+
+```powershell
+winget install -e Python.Python.3
+winget install -e Kitware.CMake
+winget install -e Git.Git
+```
+
+Then edit your system's `PATH` variable and add: `C:\Program Files\CMake\bin`.
+See
+[this guide on editing the system `PATH`](https://www.java.com/en/download/help/path.html)
+from the Java documentation.
+
+[winget]: https://github.com/microsoft/winget-cli
+
+There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by
+Visual Studio and the GNU ABI used by the GCC toolchain. Which version of Rust
+you need depends largely on what C/C++ libraries you want to interoperate with.
+Use the MSVC build of Rust to interop with software produced by Visual Studio
+and the GNU build to interop with GNU software built using the MinGW/MSYS2
+toolchain.
+
+### MinGW
+
+[MSYS2][msys2] can be used to easily build Rust on Windows:
+
+[msys2]: https://www.msys2.org/
+
+1. Download the latest [MSYS2 installer][msys2] and go through the installer.
+
+2. Run `mingw32_shell.bat` or `mingw64_shell.bat` from the MSYS2 installation
+   directory (e.g. `C:\msys64`), depending on whether you want 32-bit or 64-bit
+   Rust. (As of the latest version of MSYS2 you have to run `msys2_shell.cmd
+   -mingw32` or `msys2_shell.cmd -mingw64` from the command line instead.)
+
+3. From this terminal, install the required tools:
+
+   ```sh
+   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
+   pacman -Sy pacman-mirrors
+
+   # Install build tools needed for Rust. If you're building a 32-bit compiler,
+   # then replace "x86_64" below with "i686". If you've already got Git, Python,
+   # or CMake installed and in PATH you can remove them from this list.
+   # Note that it is important that you do **not** use the 'python2', 'cmake',
+   # and 'ninja' packages from the 'msys2' subsystem.
+   # The build has historically been known to fail with these packages.
+   pacman -S git \
+               make \
+               diffutils \
+               tar \
+               mingw-w64-x86_64-python \
+               mingw-w64-x86_64-cmake \
+               mingw-w64-x86_64-gcc \
+               mingw-w64-x86_64-ninja
+   ```
+
+4. Navigate to Rust's source code (or clone it), then build it:
+
+   ```sh
+   python x.py setup user && python x.py build && python x.py install
+   ```
+
+### MSVC
+
+MSVC builds of Rust additionally require an installation of Visual Studio 2017
+(or later) so `rustc` can use its linker. The simplest way is to get
+[Visual Studio], check the "C++ build tools" and "Windows 10 SDK" workload.
+
+[Visual Studio]: https://visualstudio.microsoft.com/downloads/
+
+(If you're installing CMake yourself, be careful that "C++ CMake tools for
+Windows" doesn't get included under "Individual components".)
+
+With these dependencies installed, you can build the compiler in a `cmd.exe`
+shell with:
+
+```sh
+python x.py setup user
+python x.py build
+```
+
+Right now, building Rust only works with some known versions of Visual Studio.
+If you have a more recent version installed and the build system doesn't
+understand, you may need to force rustbuild to use an older version.
+This can be done by manually calling the appropriate vcvars file before running
+the bootstrap.
+
+```batch
+CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"
+python x.py build
+```
+
+### Specifying an ABI
+
+Each specific ABI can also be used from either environment (for example, using
+the GNU ABI in PowerShell) by using an explicit build triple. The available
+Windows build triples are:
+- GNU ABI (using GCC)
+    - `i686-pc-windows-gnu`
+    - `x86_64-pc-windows-gnu`
+- The MSVC ABI
+    - `i686-pc-windows-msvc`
+    - `x86_64-pc-windows-msvc`
+
+The build triple can be specified by either specifying `--build=<triple>` when
+invoking `x.py` commands, or by creating a `config.toml` file (as described in
+[Building on a Unix-like system](#building-on-a-unix-like-system)), and passing
+`--set build.build=<triple>` to `./configure`.
+
+## Building Documentation
+
+If you'd like to build the documentation, it's almost the same:
+
+```sh
+./x.py doc
+```
+
+The generated documentation will appear under `doc` in the `build` directory for
+the ABI used. That is, if the ABI was `x86_64-pc-windows-msvc`, the directory
+will be `build\x86_64-pc-windows-msvc\doc`.
+
+## Notes
+
+Since the Rust compiler is written in Rust, it must be built by a precompiled
+"snapshot" version of itself (made in an earlier stage of development).
+As such, source builds require an Internet connection to fetch snapshots, and an
+OS that can execute the available snapshot binaries.
+
+See https://doc.rust-lang.org/nightly/rustc/platform-support.html for a list of
+supported platforms.
+Only "host tools" platforms have a pre-compiled snapshot binary available; to
+compile for a platform without host tools you must cross-compile.
+
+You may find that other platforms work, but these are our officially supported
+build environments that are most likely to work.

README.md

@@ -15,9 +15,6 @@ If you wish to _contribute_ to the compiler, you should read
 <summary>Table of Contents</summary>
 
 - [Quick Start](#quick-start)
-- [Installing from Source](#installing-from-source)
-- [Building Documentation](#building-documentation)
-- [Notes](#notes)
 - [Getting Help](#getting-help)
 - [Contributing](#contributing)
 - [License](#license)
@@ -32,255 +29,9 @@ Read ["Installation"] from [The Book].
 ["Installation"]: https://doc.rust-lang.org/book/ch01-01-installation.html
 [The Book]: https://doc.rust-lang.org/book/index.html
 
-## Installing from Source
+## Installing from source
 
-The Rust build system uses a Python script called `x.py` to build the compiler,
+If you really want to install from source (though this is not recommended), see [INSTALL.md](INSTALL.md).
-which manages the bootstrapping process. It lives at the root of the project.
-It also uses a file named `config.toml` to determine various configuration
-settings for the build. You can see a full list of options in
-`config.example.toml`.
-
-The `x.py` command can be run directly on most Unix systems in the following
-format:
-
-```sh
-./x.py <subcommand> [flags]
-```
-
-This is how the documentation and examples assume you are running `x.py`.
-See the [rustc dev guide][rustcguidebuild] if this does not work on your
-platform.
-
-More information about `x.py` can be found by running it with the `--help` flag
-or reading the [rustc dev guide][rustcguidebuild].
-
-[gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.html
-[rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#what-is-xpy
-
-### Dependencies
-
-Make sure you have installed the dependencies:
-
-* `python` 3 or 2.7
-* `git`
-* A C compiler (when building for the host, `cc` is enough; cross-compiling may
-  need additional compilers)
-* `curl` (not needed on Windows)
-* `pkg-config` if you are compiling on Linux and targeting Linux
-* `libiconv` (already included with glibc on Debian-based distros)
-
-To build Cargo, you'll also need OpenSSL (`libssl-dev` or `openssl-devel` on
-most Unix distros).
-
-If building LLVM from source, you'll need additional tools:
-
-* `g++`, `clang++`, or MSVC with versions listed on
-  [LLVM's documentation](https://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library)
-* `ninja`, or GNU `make` 3.81 or later (Ninja is recommended, especially on
-  Windows)
-* `cmake` 3.13.4 or later
-* `libstdc++-static` may be required on some Linux distributions such as Fedora
-  and Ubuntu
-
-On tier 1 or tier 2 with host tools platforms, you can also choose to download
-LLVM by setting `llvm.download-ci-llvm = true`.
-Otherwise, you'll need LLVM installed and `llvm-config` in your path.
-See [the rustc-dev-guide for more info][sysllvm].
-
-[sysllvm]: https://rustc-dev-guide.rust-lang.org/building/new-target.html#using-pre-built-llvm
-
-
-### Building on a Unix-like system
-
-#### Build steps
-
-1. Clone the [source] with `git`:
-
-   ```sh
-   git clone https://github.com/rust-lang/rust.git
-   cd rust
-   ```
-
-[source]: https://github.com/rust-lang/rust
-
-2. Configure the build settings:
-
-   ```sh
-   ./configure
-   ```
-
-   If you plan to use `x.py install` to create an installation, it is
-   recommended that you set the `prefix` value in the `[install]` section to a
-   directory: `./configure --set install.prefix=<path>`
-
-3. Build and install:
-
-   ```sh
-   ./x.py build && ./x.py install
-   ```
-
-   When complete, `./x.py install` will place several programs into
-   `$PREFIX/bin`: `rustc`, the Rust compiler, and `rustdoc`, the
-   API-documentation tool. By default, it will also include [Cargo], Rust's
-   package manager. You can disable this behavior by passing
-   `--set build.extended=false` to `./configure`.
-
-[Cargo]: https://github.com/rust-lang/cargo
-
-#### Configure and Make
-
-This project provides a configure script and makefile (the latter of which just
-invokes `x.py`). `./configure` is the recommended way to programmatically
-generate a `config.toml`. `make` is not recommended (we suggest using `x.py`
-directly), but it is supported and we try not to break it unnecessarily.
-
-```sh
-./configure
-make && sudo make install
-```
-
-`configure` generates a `config.toml` which can also be used with normal `x.py`
-invocations.
-
-### Building on Windows
-
-On Windows, we suggest using [winget] to install dependencies by running the
-following in a terminal:
-
-```powershell
-winget install -e Python.Python.3
-winget install -e Kitware.CMake
-winget install -e Git.Git
-```
-
-Then edit your system's `PATH` variable and add: `C:\Program Files\CMake\bin`.
-See
-[this guide on editing the system `PATH`](https://www.java.com/en/download/help/path.html)
-from the Java documentation.
-
-[winget]: https://github.com/microsoft/winget-cli
-
-There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by
-Visual Studio and the GNU ABI used by the GCC toolchain. Which version of Rust
-you need depends largely on what C/C++ libraries you want to interoperate with.
-Use the MSVC build of Rust to interop with software produced by Visual Studio
-and the GNU build to interop with GNU software built using the MinGW/MSYS2
-toolchain.
-
-#### MinGW
-
-[MSYS2][msys2] can be used to easily build Rust on Windows:
-
-[msys2]: https://www.msys2.org/
-
-1. Download the latest [MSYS2 installer][msys2] and go through the installer.
-
-2. Run `mingw32_shell.bat` or `mingw64_shell.bat` from the MSYS2 installation
-   directory (e.g. `C:\msys64`), depending on whether you want 32-bit or 64-bit
-   Rust. (As of the latest version of MSYS2 you have to run `msys2_shell.cmd
-   -mingw32` or `msys2_shell.cmd -mingw64` from the command line instead.)
-
-3. From this terminal, install the required tools:
-
-   ```sh
-   # Update package mirrors (may be needed if you have a fresh install of MSYS2)
-   pacman -Sy pacman-mirrors
-
-   # Install build tools needed for Rust. If you're building a 32-bit compiler,
-   # then replace "x86_64" below with "i686". If you've already got Git, Python,
-   # or CMake installed and in PATH you can remove them from this list.
-   # Note that it is important that you do **not** use the 'python2', 'cmake',
-   # and 'ninja' packages from the 'msys2' subsystem.
-   # The build has historically been known to fail with these packages.
-   pacman -S git \
-               make \
-               diffutils \
-               tar \
-               mingw-w64-x86_64-python \
-               mingw-w64-x86_64-cmake \
-               mingw-w64-x86_64-gcc \
-               mingw-w64-x86_64-ninja
-   ```
-
-4. Navigate to Rust's source code (or clone it), then build it:
-
-   ```sh
-   python x.py setup user && python x.py build && python x.py install
-   ```
-
-#### MSVC
-
-MSVC builds of Rust additionally require an installation of Visual Studio 2017
-(or later) so `rustc` can use its linker. The simplest way is to get
-[Visual Studio], check the "C++ build tools" and "Windows 10 SDK" workload.
-
-[Visual Studio]: https://visualstudio.microsoft.com/downloads/
-
-(If you're installing CMake yourself, be careful that "C++ CMake tools for
-Windows" doesn't get included under "Individual components".)
-
-With these dependencies installed, you can build the compiler in a `cmd.exe`
-shell with:
-
-```sh
-python x.py setup user
-python x.py build
-```
-
-Right now, building Rust only works with some known versions of Visual Studio.
-If you have a more recent version installed and the build system doesn't
-understand, you may need to force rustbuild to use an older version.
-This can be done by manually calling the appropriate vcvars file before running
-the bootstrap.
-
-```batch
-CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"
-python x.py build
-```
-
-#### Specifying an ABI
-
-Each specific ABI can also be used from either environment (for example, using
-the GNU ABI in PowerShell) by using an explicit build triple. The available
-Windows build triples are:
-- GNU ABI (using GCC)
-    - `i686-pc-windows-gnu`
-    - `x86_64-pc-windows-gnu`
-- The MSVC ABI
-    - `i686-pc-windows-msvc`
-    - `x86_64-pc-windows-msvc`
-
-The build triple can be specified by either specifying `--build=<triple>` when
-invoking `x.py` commands, or by creating a `config.toml` file (as described in
-[Building on a Unix-like system](#building-on-a-unix-like-system)), and passing
-`--set build.build=<triple>` to `./configure`.
-
-## Building Documentation
-
-If you'd like to build the documentation, it's almost the same:
-
-```sh
-./x.py doc
-```
-
-The generated documentation will appear under `doc` in the `build` directory for
-the ABI used. That is, if the ABI was `x86_64-pc-windows-msvc`, the directory
-will be `build\x86_64-pc-windows-msvc\doc`.
-
-## Notes
-
-Since the Rust compiler is written in Rust, it must be built by a precompiled
-"snapshot" version of itself (made in an earlier stage of development).
-As such, source builds require an Internet connection to fetch snapshots, and an
-OS that can execute the available snapshot binaries.
-
-See https://doc.rust-lang.org/nightly/rustc/platform-support.html for a list of
-supported platforms.
-Only "host tools" platforms have a pre-compiled snapshot binary available; to
-compile for a platform without host tools you must cross-compile.
-
-You may find that other platforms work, but these are our officially supported
-build environments that are most likely to work.
 
 ## Getting Help
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -786,7 +786,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
                 self.dcx().create_err(errs::SelfImportOnlyInImportListWithNonEmptyPrefix { span })
             }
-            ResolutionError::FailedToResolve { last_segment, label, suggestion, module } => {
+            ResolutionError::FailedToResolve { segment, label, suggestion, module } => {
                 let mut err =
                     struct_span_code_err!(self.dcx(), span, E0433, "failed to resolve: {}", &label);
                 err.span_label(span, label);
@@ -801,9 +801,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
                 if let Some(ModuleOrUniformRoot::Module(module)) = module
                     && let Some(module) = module.opt_def_id()
-                    && let Some(last_segment) = last_segment
+                    && let Some(segment) = segment
                 {
-                    self.find_cfg_stripped(&mut err, &last_segment, module);
+                    self.find_cfg_stripped(&mut err, &segment, module);
                 }
 
                 err
@@ -981,12 +981,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
             VisResolutionError::FailedToResolve(span, label, suggestion) => self.into_struct_error(
                 span,
-                ResolutionError::FailedToResolve {
+                ResolutionError::FailedToResolve { segment: None, label, suggestion, module: None },
-                    last_segment: None,
-                    label,
-                    suggestion,
-                    module: None,
-                },
             ),
             VisResolutionError::ExpectedFound(span, path_str, res) => {
                 self.dcx().create_err(errs::ExpectedFound { span, res, path_str })
@@ -2450,7 +2445,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
     pub(crate) fn find_cfg_stripped(
         &mut self,
         err: &mut Diagnostic,
-        last_segment: &Symbol,
+        segment: &Symbol,
         module: DefId,
     ) {
         let local_items;
@@ -2469,7 +2464,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         };
 
         for &StrippedCfgItem { parent_module, name, ref cfg } in symbols {
-            if parent_module != module || name.name != *last_segment {
+            if parent_module != module || name.name != *segment {
                 continue;
             }
 

compiler/rustc_resolve/src/ident.rs

@@ -1381,13 +1381,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                             continue;
                         }
                     }
-                    return PathResult::failed(
+                    return PathResult::failed(ident, false, finalize.is_some(), module, || {
-                        ident.span,
+                        ("there are too many leading `super` keywords".to_string(), None)
-                        false,
+                    });
-                        finalize.is_some(),
-                        module,
-                        || ("there are too many leading `super` keywords".to_string(), None),
-                    );
                 }
                 if segment_idx == 0 {
                     if name == kw::SelfLower {
@@ -1419,7 +1415,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
             // Report special messages for path segment keywords in wrong positions.
             if ident.is_path_segment_keyword() && segment_idx != 0 {
-                return PathResult::failed(ident.span, false, finalize.is_some(), module, || {
+                return PathResult::failed(ident, false, finalize.is_some(), module, || {
                     let name_str = if name == kw::PathRoot {
                         "crate root".to_string()
                     } else {
@@ -1515,7 +1511,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         ));
                     } else {
                         return PathResult::failed(
-                            ident.span,
+                            ident,
                             is_last,
                             finalize.is_some(),
                             module,
@@ -1541,24 +1537,18 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         }
                     }
 
-                    return PathResult::failed(
+                    return PathResult::failed(ident, is_last, finalize.is_some(), module, || {
-                        ident.span,
+                        self.report_path_resolution_error(
-                        is_last,
+                            path,
-                        finalize.is_some(),
+                            opt_ns,
-                        module,
+                            parent_scope,
-                        || {
+                            ribs,
-                            self.report_path_resolution_error(
+                            ignore_binding,
-                                path,
+                            module,
-                                opt_ns,
+                            segment_idx,
-                                parent_scope,
+                            ident,
-                                ribs,
+                        )
-                                ignore_binding,
+                    });
-                                module,
-                                segment_idx,
-                                ident,
-                            )
-                        },
-                    );
                 }
             }
         }

compiler/rustc_resolve/src/imports.rs

@@ -886,6 +886,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             PathResult::Failed {
                 is_error_from_last_segment: false,
                 span,
+                segment_name,
                 label,
                 suggestion,
                 module,
@@ -895,7 +896,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     self.report_error(
                         span,
                         ResolutionError::FailedToResolve {
-                            last_segment: None,
+                            segment: Some(segment_name),
                             label,
                             suggestion,
                             module,

compiler/rustc_resolve/src/late.rs

@@ -4054,11 +4054,12 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 label,
                 suggestion,
                 module,
+                segment_name,
             } => {
                 return Err(respan(
                     span,
                     ResolutionError::FailedToResolve {
-                        last_segment: None,
+                        segment: Some(segment_name),
                         label,
                         suggestion,
                         module,

compiler/rustc_resolve/src/lib.rs

@@ -213,7 +213,7 @@ enum ResolutionError<'a> {
     SelfImportOnlyInImportListWithNonEmptyPrefix,
     /// Error E0433: failed to resolve.
     FailedToResolve {
-        last_segment: Option<Symbol>,
+        segment: Option<Symbol>,
         label: String,
         suggestion: Option<Suggestion>,
         module: Option<ModuleOrUniformRoot<'a>>,
@@ -396,12 +396,14 @@ enum PathResult<'a> {
         suggestion: Option<Suggestion>,
         is_error_from_last_segment: bool,
         module: Option<ModuleOrUniformRoot<'a>>,
+        /// The segment name of target
+        segment_name: Symbol,
     },
 }
 
 impl<'a> PathResult<'a> {
     fn failed(
-        span: Span,
+        ident: Ident,
         is_error_from_last_segment: bool,
         finalize: bool,
         module: Option<ModuleOrUniformRoot<'a>>,
@@ -409,7 +411,14 @@ impl<'a> PathResult<'a> {
     ) -> PathResult<'a> {
         let (label, suggestion) =
             if finalize { label_and_suggestion() } else { (String::new(), None) };
-        PathResult::Failed { span, label, suggestion, is_error_from_last_segment, module }
+        PathResult::Failed {
+            span: ident.span,
+            segment_name: ident.name,
+            label,
+            suggestion,
+            is_error_from_last_segment,
+            module,
+        }
     }
 }
 

compiler/rustc_resolve/src/macros.rs

@@ -773,7 +773,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     self.report_error(
                         span,
                         ResolutionError::FailedToResolve {
-                            last_segment: path.last().map(|segment| segment.ident.name),
+                            segment: path.last().map(|segment| segment.ident.name),
                             label,
                             suggestion,
                             module,

library/std/src/sys/mod.rs

@@ -3,6 +3,8 @@
 /// descriptors.
 mod pal;
 
+mod personality;
+
 // FIXME(117276): remove this, move feature implementations into individual
 //                submodules.
 pub use pal::*;

library/std/src/sys/pal/mod.rs

@@ -23,7 +23,6 @@
 #![allow(missing_debug_implementations)]
 
 pub mod common;
-mod personality;
 
 cfg_if::cfg_if! {
     if #[cfg(unix)] {

src/doc/rustc/src/platform-support/unknown-uefi.md

@@ -82,13 +82,29 @@ rustup target add x86_64-unknown-uefi
 cargo build --target x86_64-unknown-uefi
 ```
 
+### Building a driver
+
+There are three types of UEFI executables: application, boot service
+driver, and runtime driver. All of Rust's UEFI targets default to
+producing applications. To build a driver instead, pass a
+[`subsystem`][linker-subsystem] linker flag with a value of
+`efi_boot_service_driver` or `efi_runtime_driver`.
+
+Example:
+
+```toml
+# In .cargo/config.toml:
+[build]
+rustflags = ["-C", "link-args=/subsystem:efi_runtime_driver"]
+```
+
 ## Testing
 
 UEFI applications can be copied into the ESP on any UEFI system and executed
 via the firmware boot menu. The qemu suite allows emulating UEFI systems and
 executing UEFI applications as well. See its documentation for details.
 
-The [uefi-run](https://github.com/Richard-W/uefi-run) rust tool is a simple
+The [uefi-run] rust tool is a simple
 wrapper around `qemu` that can spawn UEFI applications in qemu. You can install
 it via `cargo install uefi-run` and execute qemu applications as
 `uefi-run ./application.efi`.
@@ -132,19 +148,19 @@ have been developed to provide access to UEFI protocols and make UEFI
 programming more ergonomic in rust. The following list is a short overview (in
 alphabetical ordering):
 
-- **efi**: *Ergonomic Rust bindings for writing UEFI applications*. Provides
+- **[efi][efi-crate]**: *Ergonomic Rust bindings for writing UEFI applications*. Provides
   _rustified_ access to UEFI protocols, implements allocators and a safe
   environment to write UEFI applications.
-- **r-efi**: *UEFI Reference Specification Protocol Constants and Definitions*.
+- **[r-efi]**: *UEFI Reference Specification Protocol Constants and Definitions*.
   A pure transpose of the UEFI specification into rust. This provides the raw
   definitions from the specification, without any extended helpers or
   _rustification_. It serves as baseline to implement any more elaborate rust
   UEFI layers.
-- **uefi-rs**: *Safe and easy-to-use wrapper for building UEFI apps*. An
+- **[uefi-rs]**: *Safe and easy-to-use wrapper for building UEFI apps*. An
   elaborate library providing safe abstractions for UEFI protocols and
   features. It implements allocators and provides an execution environment to
   UEFI applications written in rust.
-- **uefi-run**: *Run UEFI applications*. A small wrapper around _qemu_ to spawn
+- **[uefi-run]**: *Run UEFI applications*. A small wrapper around _qemu_ to spawn
   UEFI applications in an emulated `x86_64` machine.
 
 ## Example: Freestanding
@@ -311,3 +327,9 @@ pub fn main() {
 The current implementation of std makes `BootServices` unavailable once `ExitBootServices` is called. Refer to [Runtime Drivers](https://edk2-docs.gitbook.io/edk-ii-uefi-driver-writer-s-guide/7_driver_entry_point/711_runtime_drivers) for more information regarding how to handle switching from using physical addresses to using virtual addresses.
 
 Note: It should be noted that it is up to the user to drop all allocated memory before `ExitBootServices` is called.
+
+[efi-crate]: https://github.com/gurry/efi
+[linker-subsystem]: https://learn.microsoft.com/en-us/cpp/build/reference/subsystem
+[r-efi]: https://github.com/r-efi/r-efi
+[uefi-rs]: https://github.com/rust-osdev/uefi-rs
+[uefi-run]: https://github.com/Richard-W/uefi-run

src/tools/tidy/src/pal.rs

@@ -46,8 +46,8 @@ const EXCEPTION_PATHS: &[&str] = &[
     // we must use `#[cfg(windows)]` to conditionally compile the
     // correct `VaList` structure for windows.
     "library/core/src/ffi/mod.rs",
-    "library/std/src/sys/pal/", // Platform-specific code for std lives here.
+    "library/std/src/sys", // Platform-specific code for std lives here.
-    "library/std/src/os",       // Platform-specific public interfaces
+    "library/std/src/os",  // Platform-specific public interfaces
     // Temporary `std` exceptions
     // FIXME: platform-specific code should be moved to `sys`
     "library/std/src/io/copy.rs",

tests/ui/cfg/diagnostics-cross-crate.rs

@@ -14,9 +14,9 @@ fn main() {
 
     // The module isn't found - we would like to get a diagnostic, but currently don't due to
     // the awkward way the resolver diagnostics are currently implemented.
-    // FIXME(Nilstrieb): Also add a note to the cfg diagnostic here
     cfged_out::inner::doesnt_exist::hello(); //~ ERROR failed to resolve
     //~^ NOTE could not find `doesnt_exist` in `inner`
+    //~| NOTE found an item that was configured out
 
     // It should find the one in the right module, not the wrong one.
     cfged_out::inner::right::meow(); //~ ERROR cannot find function

tests/ui/cfg/diagnostics-cross-crate.stderr

@@ -1,8 +1,14 @@
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-cross-crate.rs:18:23
+  --> $DIR/diagnostics-cross-crate.rs:17:23
    |
 LL |     cfged_out::inner::doesnt_exist::hello();
    |                       ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
+   |
+note: found an item that was configured out
+  --> $DIR/auxiliary/cfged_out.rs:6:13
+   |
+LL |     pub mod doesnt_exist {
+   |             ^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in crate `cfged_out`
   --> $DIR/diagnostics-cross-crate.rs:7:16

tests/ui/cfg/diagnostics-same-crate.rs

@@ -4,7 +4,7 @@ pub mod inner {
     //~^ NOTE found an item that was configured out
 
     #[cfg(FALSE)]
-    pub mod doesnt_exist {
+    pub mod doesnt_exist { //~ NOTE found an item that was configured out
         pub fn hello() {}
     }
 
@@ -34,7 +34,6 @@ fn main() {
 
     // The module isn't found - we would like to get a diagnostic, but currently don't due to
     // the awkward way the resolver diagnostics are currently implemented.
-    // FIXME(Nilstrieb): Also add a note to the cfg diagnostic here
     inner::doesnt_exist::hello(); //~ ERROR failed to resolve
     //~| NOTE could not find `doesnt_exist` in `inner`
 

tests/ui/cfg/diagnostics-same-crate.stderr

@@ -1,8 +1,14 @@
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-same-crate.rs:38:12
+  --> $DIR/diagnostics-same-crate.rs:37:12
    |
 LL |     inner::doesnt_exist::hello();
    |            ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-same-crate.rs:7:13
+   |
+LL |     pub mod doesnt_exist {
+   |             ^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
   --> $DIR/diagnostics-same-crate.rs:32:12
@@ -17,7 +23,7 @@ LL |     pub fn uwu() {}
    |            ^^^
 
 error[E0425]: cannot find function `meow` in module `inner::right`
-  --> $DIR/diagnostics-same-crate.rs:42:19
+  --> $DIR/diagnostics-same-crate.rs:41:19
    |
 LL |     inner::right::meow();
    |                   ^^^^ not found in `inner::right`
@@ -36,7 +42,7 @@ LL |     uwu();
    |     ^^^ not found in this scope
 
 error[E0425]: cannot find function `vanished` in this scope
-  --> $DIR/diagnostics-same-crate.rs:49:5
+  --> $DIR/diagnostics-same-crate.rs:48:5
    |
 LL |     vanished();
    |     ^^^^^^^^ not found in this scope

triagebot.toml

@@ -22,6 +22,7 @@ allow-unauthenticated = [
     "perf-*",
     "AsyncAwait-OnDeck",
     "needs-triage",
+    "has-merge-commits",
 ]
 
 [review-submitted]