Auto merge of #71059 - Dylan-DPC:rollup-zgu6jmx, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #71029 (Partial work on building with Cargo)
 - #71034 (Clean up E0515 explanation)
 - #71041 (Update links of `rustc guide`)
 - #71048 (Normalize source when loading external foreign source into SourceMap)
 - #71053 (Add some basic docs to `sym` and `kw` modules)
 - #71057 (Clean up E0516 explanation)

Failed merges:

r? @ghost

24 files changed, 113 insertions, 40 deletions

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 32ce170a5a1..f44096af6dd 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -186,6 +186,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: Interned<String>, cargo: &mut Ca
     // `compiler-rt` is located.
     let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
     let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
+        // Note that `libprofiler_builtins/build.rs` also computes this so if
+        // you're changing something here please also change that.
         cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);
         " compiler-builtins-c".to_string()
     } else {
diff --git a/src/libprofiler_builtins/build.rs b/src/libprofiler_builtins/build.rs
index c990b289335..e23e2f2c130 100644
--- a/src/libprofiler_builtins/build.rs
+++ b/src/libprofiler_builtins/build.rs
@@ -63,8 +63,9 @@ fn main() {
         cfg.define("COMPILER_RT_HAS_ATOMICS", Some("1"));
     }
 
-    let root = env::var_os("RUST_COMPILER_RT_ROOT").unwrap();
-    let root = Path::new(&root);
+    // Note that this should exist if we're going to run (otherwise we just
+    // don't build profiler builtins at all).
+    let root = Path::new("../llvm-project/compiler-rt");
 
     let src_root = root.join("lib").join("profile");
     for src in profile_sources {
diff --git a/src/librustc_data_structures/Cargo.toml b/src/librustc_data_structures/Cargo.toml
index c5707bd24f7..6d7022acc78 100644
--- a/src/librustc_data_structures/Cargo.toml
+++ b/src/librustc_data_structures/Cargo.toml
@@ -27,6 +27,7 @@ smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_index = { path = "../librustc_index", package = "rustc_index" }
 bitflags = "1.2.1"
 measureme = "0.7.1"
+libc = "0.2"
 
 [dependencies.parking_lot]
 version = "0.10"
diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index ba82e58d7a9..d0180911567 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -26,8 +26,6 @@
 
 #[macro_use]
 extern crate log;
-#[cfg(unix)]
-extern crate libc;
 #[macro_use]
 extern crate cfg_if;
 
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 652f16c2e08..cfd103aed32 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -11,6 +11,7 @@ crate-type = ["dylib"]
 
 [dependencies]
 lazy_static = "1.0"
+libc = "0.2"
 log = "0.4"
 env_logger = { version = "0.7", default-features = false }
 rustc_middle = { path = "../librustc_middle" }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index acf8f1adbc2..0e3199975f9 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -8,9 +8,6 @@
 #![feature(nll)]
 #![recursion_limit = "256"]
 
-pub extern crate getopts;
-#[cfg(unix)]
-extern crate libc;
 #[macro_use]
 extern crate log;
 #[macro_use]
@@ -37,6 +34,7 @@ use rustc_save_analysis::DumpHandler;
 use rustc_serialize::json::{self, ToJson};
 use rustc_session::config::nightly_options;
 use rustc_session::config::{ErrorOutputType, Input, OutputType, PrintRequest};
+use rustc_session::getopts;
 use rustc_session::lint::{Lint, LintId};
 use rustc_session::{config, DiagnosticOutput, Session};
 use rustc_session::{early_error, early_warn};
diff --git a/src/librustc_error_codes/error_codes/E0515.md b/src/librustc_error_codes/error_codes/E0515.md
index 9580b6f92ac..0f4fbf67223 100644
--- a/src/librustc_error_codes/error_codes/E0515.md
+++ b/src/librustc_error_codes/error_codes/E0515.md
@@ -1,7 +1,4 @@
-Cannot return value that references local variable
-
-Local variables, function parameters and temporaries are all dropped before the
-end of the function body. So a reference to them cannot be returned.
+A reference to a local variable was returned.
 
 Erroneous code example:
 
@@ -20,6 +17,9 @@ fn get_dangling_iterator<'a>() -> Iter<'a, i32> {
 }
 ```
 
+Local variables, function parameters and temporaries are all dropped before the
+end of the function body. So a reference to them cannot be returned.
+
 Consider returning an owned value instead:
 
 ```
diff --git a/src/librustc_error_codes/error_codes/E0516.md b/src/librustc_error_codes/error_codes/E0516.md
index 815d7609013..935c31bbab9 100644
--- a/src/librustc_error_codes/error_codes/E0516.md
+++ b/src/librustc_error_codes/error_codes/E0516.md
@@ -1,4 +1,5 @@
 The `typeof` keyword is currently reserved but unimplemented.
+
 Erroneous code example:
 
 ```compile_fail,E0516
diff --git a/src/librustc_infer/traits/mod.rs b/src/librustc_infer/traits/mod.rs
index 758a0b39d43..2210c663d14 100644
--- a/src/librustc_infer/traits/mod.rs
+++ b/src/librustc_infer/traits/mod.rs
@@ -1,6 +1,6 @@
-//! Trait Resolution. See the [rustc guide] for more information on how this works.
+//! Trait Resolution. See the [rustc-dev-guide] for more information on how this works.
 //!
-//! [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/resolution.html
+//! [rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html
 
 mod engine;
 pub mod error_reporting;
diff --git a/src/librustc_interface/Cargo.toml b/src/librustc_interface/Cargo.toml
index c9d81e51641..8ea866d7cab 100644
--- a/src/librustc_interface/Cargo.toml
+++ b/src/librustc_interface/Cargo.toml
@@ -10,6 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
+libc = "0.2"
 log = "0.4"
 rayon = { version = "0.3.0", package = "rustc-rayon" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_interface/lib.rs b/src/librustc_interface/lib.rs
index ba1e2216ca8..0650d090034 100644
--- a/src/librustc_interface/lib.rs
+++ b/src/librustc_interface/lib.rs
@@ -6,9 +6,6 @@
 #![feature(generators)]
 #![recursion_limit = "256"]
 
-#[cfg(unix)]
-extern crate libc;
-
 mod callbacks;
 pub mod interface;
 mod passes;
diff --git a/src/librustc_interface/tests.rs b/src/librustc_interface/tests.rs
index b452ccfe33a..c75f3b279a2 100644
--- a/src/librustc_interface/tests.rs
+++ b/src/librustc_interface/tests.rs
@@ -1,5 +1,3 @@
-extern crate getopts;
-
 use crate::interface::parse_cfgspecs;
 
 use rustc_data_structures::fx::FxHashSet;
@@ -9,6 +7,7 @@ use rustc_session::config::{build_configuration, build_session_options, to_crate
 use rustc_session::config::{rustc_optgroups, ErrorOutputType, ExternLocation, Options, Passes};
 use rustc_session::config::{ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
 use rustc_session::config::{Externs, OutputType, OutputTypes, SymbolManglingVersion};
+use rustc_session::getopts;
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::{build_session, Session};
diff --git a/src/librustc_llvm/build.rs b/src/librustc_llvm/build.rs
index fcaeaf2e4b0..f14fc9fc2eb 100644
--- a/src/librustc_llvm/build.rs
+++ b/src/librustc_llvm/build.rs
@@ -24,18 +24,28 @@ fn main() {
     build_helper::restore_library_path();
 
     let target = env::var("TARGET").expect("TARGET was not set");
-    let llvm_config = env::var_os("LLVM_CONFIG").map(PathBuf::from).unwrap_or_else(|| {
-        if let Some(dir) = env::var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
-            let to_test =
-                dir.parent().unwrap().parent().unwrap().join(&target).join("llvm/bin/llvm-config");
-            if Command::new(&to_test).output().is_ok() {
-                return to_test;
+    let llvm_config =
+        env::var_os("LLVM_CONFIG").map(|x| Some(PathBuf::from(x))).unwrap_or_else(|| {
+            if let Some(dir) = env::var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
+                let to_test = dir
+                    .parent()
+                    .unwrap()
+                    .parent()
+                    .unwrap()
+                    .join(&target)
+                    .join("llvm/bin/llvm-config");
+                if Command::new(&to_test).output().is_ok() {
+                    return Some(to_test);
+                }
             }
-        }
-        PathBuf::from("llvm-config")
-    });
+            None
+        });
+
+    if let Some(llvm_config) = &llvm_config {
+        println!("cargo:rerun-if-changed={}", llvm_config.display());
+    }
+    let llvm_config = llvm_config.unwrap_or_else(|| PathBuf::from("llvm-config"));
 
-    println!("cargo:rerun-if-changed={}", llvm_config.display());
     println!("cargo:rerun-if-env-changed=LLVM_CONFIG");
 
     // Test whether we're cross-compiling LLVM. This is a pretty rare case
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index a88ccd52e91..b03e884cdaf 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -11,6 +11,7 @@ doctest = false
 
 [dependencies]
 flate2 = "1.0"
+libc = "0.2"
 log = "0.4"
 memmap = "0.7"
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index 22a2bf28041..4659be8c195 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -10,7 +10,6 @@
 #![feature(stmt_expr_attributes)]
 #![recursion_limit = "256"]
 
-extern crate libc;
 extern crate proc_macro;
 
 #[macro_use]
diff --git a/src/librustc_session/Cargo.toml b/src/librustc_session/Cargo.toml
index 3895d0f8061..814073bb4f7 100644
--- a/src/librustc_session/Cargo.toml
+++ b/src/librustc_session/Cargo.toml
@@ -9,6 +9,7 @@ name = "rustc_session"
 path = "lib.rs"
 
 [dependencies]
+getopts = "0.2"
 log = "0.4"
 rustc_errors = { path = "../librustc_errors" }
 rustc_feature = { path = "../librustc_feature" }
diff --git a/src/librustc_session/lib.rs b/src/librustc_session/lib.rs
index cc4d525d628..2ff92c46d12 100644
--- a/src/librustc_session/lib.rs
+++ b/src/librustc_session/lib.rs
@@ -1,10 +1,4 @@
 #![feature(crate_visibility_modifier)]
-#![feature(test)]
-
-// Use the test crate here so we depend on getopts through it. This allow tools to link to both
-// librustc_session and libtest.
-extern crate getopts;
-extern crate test as _;
 
 pub mod cgu_reuse_tracker;
 pub mod utils;
@@ -23,3 +17,5 @@ mod session;
 pub use session::*;
 
 pub mod output;
+
+pub use getopts;
diff --git a/src/librustc_span/lib.rs b/src/librustc_span/lib.rs
index 0d9f3f214fb..85a870ae34c 100644
--- a/src/librustc_span/lib.rs
+++ b/src/librustc_span/lib.rs
@@ -1192,8 +1192,10 @@ impl SourceFile {
                 kind: src_kind @ ExternalSourceKind::AbsentOk, ..
             } = &mut *external_src
             {
-                if let Some(src) = src {
+                if let Some(mut src) = src {
+                    // The src_hash needs to be computed on the pre-normalized src.
                     if self.src_hash.matches(&src) {
+                        normalize_src(&mut src, BytePos::from_usize(0));
                         *src_kind = ExternalSourceKind::Present(Lrc::new(src));
                         return true;
                     }
diff --git a/src/librustc_span/source_map/tests.rs b/src/librustc_span/source_map/tests.rs
index 79df1884f0d..b8459eee4ec 100644
--- a/src/librustc_span/source_map/tests.rs
+++ b/src/librustc_span/source_map/tests.rs
@@ -168,6 +168,62 @@ fn span_merging_fail() {
     assert!(sm.merge_spans(span1, span2).is_none());
 }
 
+/// Tests loading an external source file that requires normalization.
+#[test]
+fn t10() {
+    let sm = SourceMap::new(FilePathMapping::empty());
+    let unnormalized = "first line.\r\nsecond line";
+    let normalized = "first line.\nsecond line";
+
+    let src_file = sm.new_source_file(PathBuf::from("blork.rs").into(), unnormalized.to_string());
+
+    assert_eq!(src_file.src.as_ref().unwrap().as_ref(), normalized);
+    assert!(
+        src_file.src_hash.matches(unnormalized),
+        "src_hash should use the source before normalization"
+    );
+
+    let SourceFile {
+        name,
+        name_was_remapped,
+        src_hash,
+        start_pos,
+        end_pos,
+        lines,
+        multibyte_chars,
+        non_narrow_chars,
+        normalized_pos,
+        name_hash,
+        ..
+    } = (*src_file).clone();
+
+    let imported_src_file = sm.new_imported_source_file(
+        name,
+        name_was_remapped,
+        src_hash,
+        name_hash,
+        (end_pos - start_pos).to_usize(),
+        CrateNum::new(0),
+        lines,
+        multibyte_chars,
+        non_narrow_chars,
+        normalized_pos,
+        start_pos,
+        end_pos,
+    );
+
+    assert!(
+        imported_src_file.external_src.borrow().get_source().is_none(),
+        "imported source file should not have source yet"
+    );
+    imported_src_file.add_external_src(|| Some(unnormalized.to_string()));
+    assert_eq!(
+        imported_src_file.external_src.borrow().get_source().unwrap().as_ref(),
+        normalized,
+        "imported source file should be normalized"
+    );
+}
+
 /// Returns the span corresponding to the `n`th occurrence of `substring` in `source_text`.
 trait SourceMapExtension {
     fn span_substr(
diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs
index 6845cb3b9a3..4c963ac84dc 100644
--- a/src/librustc_span/symbol.rs
+++ b/src/librustc_span/symbol.rs
@@ -1153,12 +1153,20 @@ impl Interner {
 }
 
 // This module has a very short name because it's used a lot.
+/// This module contains all the defined keyword `Symbol`s.
+///
+/// Given that `kw` is imported, use them like `kw::keyword_name`.
+/// For example `kw::Loop` or `kw::Break`.
 pub mod kw {
     use super::Symbol;
     keywords!();
 }
 
 // This module has a very short name because it's used a lot.
+/// This module contains all the defined non-keyword `Symbol`s.
+///
+/// Given that `sym` is imported, use them like `sym::symbol_name`.
+/// For example `sym::rustfmt` or `sym::u8`.
 #[allow(rustc::default_hash_types)]
 pub mod sym {
     use super::Symbol;
diff --git a/src/librustc_trait_selection/lib.rs b/src/librustc_trait_selection/lib.rs
index 9ada88098a5..4796b431d8d 100644
--- a/src/librustc_trait_selection/lib.rs
+++ b/src/librustc_trait_selection/lib.rs
@@ -2,9 +2,9 @@
 //!
 //! - **Traits.** Trait resolution is implemented in the `traits` module.
 //!
-//! For more information about how rustc works, see the [rustc guide].
+//! For more information about how rustc works, see the [rustc-dev-guide].
 //!
-//! [rustc guide]: https://rust-lang.github.io/rustc-guide/
+//! [rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
 //!
 //! # Note
 //!
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 179c5bfacf3..a5a1e20396c 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -10,6 +10,7 @@ use rustc_session::config::{
     nightly_options,
 };
 use rustc_session::config::{CodegenOptions, DebuggingOptions, ErrorOutputType, Externs};
+use rustc_session::getopts;
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 99860a103d7..b0d5a8e58e1 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -15,7 +15,6 @@
 #![recursion_limit = "256"]
 
 extern crate env_logger;
-extern crate getopts;
 extern crate rustc_ast;
 extern crate rustc_ast_pretty;
 extern crate rustc_attr;
@@ -51,6 +50,7 @@ use std::panic;
 use std::process;
 
 use rustc_session::config::{make_crate_type_option, ErrorOutputType, RustcOptGroup};
+use rustc_session::getopts;
 use rustc_session::{early_error, early_warn};
 
 #[macro_use]
diff --git a/src/libstd/Cargo.toml b/src/libstd/Cargo.toml
index 3a83f3f569a..ceb39c01c67 100644
--- a/src/libstd/Cargo.toml
+++ b/src/libstd/Cargo.toml
@@ -47,7 +47,7 @@ hermit-abi = { version = "0.1.10", features = ['rustc-dep-of-std'] }
 wasi = { version = "0.9.0", features = ['rustc-dep-of-std'], default-features = false }
 
 [features]
-default = ["std_detect_file_io", "std_detect_dlsym_getauxval"]
+default = ["std_detect_file_io", "std_detect_dlsym_getauxval", "panic-unwind"]
 
 backtrace = [
   "backtrace_rs/dbghelp",          # backtrace/symbolize on MSVC