Auto merge of #54168 - kennytm:rollup, r=kennytm

Rollup of 11 pull requests

Successful merges:

 - #53371 (Do not emit E0277 on incorrect tuple destructured binding)
 - #53829 (Add rustc SHA to released DWARF debuginfo)
 - #53950 (Allow for opting out of ThinLTO and clean up LTO related cli flag handling.)
 - #53976 (Replace unwrap calls in example by expect)
 - #54070 (Add Error::description soft-deprecation to RELEASES)
 - #54076 (miri loop detector hashing)
 - #54119 (Add some unit tests for find_best_match_for_name)
 - #54147 (Add a test that tries to modify static memory at compile-time)
 - #54150 (Updated 1.29 release notes with --document-private-items flag)
 - #54163 (Update stage 0 to latest beta)
 - #54170 (COMPILER_TESTS.md has been moved)

2 files changed, 38 insertions, 30 deletions

diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 016e7adb4c9..0831e29bddd 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -97,6 +97,10 @@ fn build_libbacktrace(target: &str) -> Result<(), ()> {
         .file("../libbacktrace/sort.c")
         .file("../libbacktrace/state.c");
 
+    let any_debug = env::var("RUSTC_DEBUGINFO").unwrap_or(String::new()) == "true" ||
+        env::var("RUSTC_DEBUGINFO_LINES").unwrap_or(String::new()) == "true";
+    build.debug(any_debug);
+
     if target.contains("darwin") {
         build.file("../libbacktrace/macho.c");
     } else if target.contains("windows") {
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index 372f3e83e3d..63dd12f782f 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -102,8 +102,8 @@ use sys;
 /// }
 ///
 /// // We are certain that our string doesn't have 0 bytes in the middle,
-/// // so we can .unwrap()
-/// let c_to_print = CString::new("Hello, world!").unwrap();
+/// // so we can .expect()
+/// let c_to_print = CString::new("Hello, world!").expect("CString::new failed");
 /// unsafe {
 ///     my_printer(c_to_print.as_ptr());
 /// }
@@ -175,7 +175,7 @@ pub struct CString {
 ///     unsafe { work_with(data.as_ptr()) }
 /// }
 ///
-/// let s = CString::new("data data data data").unwrap();
+/// let s = CString::new("data data data data").expect("CString::new failed");
 /// work(&s);
 /// ```
 ///
@@ -314,7 +314,7 @@ impl CString {
     ///
     /// extern { fn puts(s: *const c_char); }
     ///
-    /// let to_print = CString::new("Hello!").unwrap();
+    /// let to_print = CString::new("Hello!").expect("CString::new failed");
     /// unsafe {
     ///     puts(to_print.as_ptr());
     /// }
@@ -398,7 +398,7 @@ impl CString {
     ///     fn some_extern_function(s: *mut c_char);
     /// }
     ///
-    /// let c_string = CString::new("Hello!").unwrap();
+    /// let c_string = CString::new("Hello!").expect("CString::new failed");
     /// let raw = c_string.into_raw();
     /// unsafe {
     ///     some_extern_function(raw);
@@ -428,7 +428,7 @@ impl CString {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new("foo").unwrap();
+    /// let c_string = CString::new("foo").expect("CString::new failed");
     ///
     /// let ptr = c_string.into_raw();
     ///
@@ -460,12 +460,12 @@ impl CString {
     /// use std::ffi::CString;
     ///
     /// let valid_utf8 = vec![b'f', b'o', b'o'];
-    /// let cstring = CString::new(valid_utf8).unwrap();
-    /// assert_eq!(cstring.into_string().unwrap(), "foo");
+    /// let cstring = CString::new(valid_utf8).expect("CString::new failed");
+    /// assert_eq!(cstring.into_string().expect("into_string() call failed"), "foo");
     ///
     /// let invalid_utf8 = vec![b'f', 0xff, b'o', b'o'];
-    /// let cstring = CString::new(invalid_utf8).unwrap();
-    /// let err = cstring.into_string().err().unwrap();
+    /// let cstring = CString::new(invalid_utf8).expect("CString::new failed");
+    /// let err = cstring.into_string().err().expect("into_string().err() failed");
     /// assert_eq!(err.utf8_error().valid_up_to(), 1);
     /// ```
 
@@ -489,7 +489,7 @@ impl CString {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new("foo").unwrap();
+    /// let c_string = CString::new("foo").expect("CString::new failed");
     /// let bytes = c_string.into_bytes();
     /// assert_eq!(bytes, vec![b'f', b'o', b'o']);
     /// ```
@@ -511,7 +511,7 @@ impl CString {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new("foo").unwrap();
+    /// let c_string = CString::new("foo").expect("CString::new failed");
     /// let bytes = c_string.into_bytes_with_nul();
     /// assert_eq!(bytes, vec![b'f', b'o', b'o', b'\0']);
     /// ```
@@ -534,7 +534,7 @@ impl CString {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new("foo").unwrap();
+    /// let c_string = CString::new("foo").expect("CString::new failed");
     /// let bytes = c_string.as_bytes();
     /// assert_eq!(bytes, &[b'f', b'o', b'o']);
     /// ```
@@ -554,7 +554,7 @@ impl CString {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new("foo").unwrap();
+    /// let c_string = CString::new("foo").expect("CString::new failed");
     /// let bytes = c_string.as_bytes_with_nul();
     /// assert_eq!(bytes, &[b'f', b'o', b'o', b'\0']);
     /// ```
@@ -573,9 +573,10 @@ impl CString {
     /// ```
     /// use std::ffi::{CString, CStr};
     ///
-    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
+    /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
     /// let c_str = c_string.as_c_str();
-    /// assert_eq!(c_str, CStr::from_bytes_with_nul(b"foo\0").unwrap());
+    /// assert_eq!(c_str,
+    ///            CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
     /// ```
     #[inline]
     #[stable(feature = "as_c_str", since = "1.20.0")]
@@ -592,16 +593,17 @@ impl CString {
     /// ```
     /// use std::ffi::{CString, CStr};
     ///
-    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
+    /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
     /// let boxed = c_string.into_boxed_c_str();
-    /// assert_eq!(&*boxed, CStr::from_bytes_with_nul(b"foo\0").unwrap());
+    /// assert_eq!(&*boxed,
+    ///            CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
     /// ```
     #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
     pub fn into_boxed_c_str(self) -> Box<CStr> {
         unsafe { Box::from_raw(Box::into_raw(self.into_inner()) as *mut CStr) }
     }
 
-    // Bypass "move out of struct which implements [`Drop`] trait" restriction.
+    /// Bypass "move out of struct which implements [`Drop`] trait" restriction.
     ///
     /// [`Drop`]: ../ops/trait.Drop.html
     fn into_inner(self) -> Box<[u8]> {
@@ -1031,7 +1033,7 @@ impl CStr {
     /// use std::ffi::{CStr, CString};
     ///
     /// unsafe {
-    ///     let cstring = CString::new("hello").unwrap();
+    ///     let cstring = CString::new("hello").expect("CString::new failed");
     ///     let cstr = CStr::from_bytes_with_nul_unchecked(cstring.to_bytes_with_nul());
     ///     assert_eq!(cstr, &*cstring);
     /// }
@@ -1058,7 +1060,7 @@ impl CStr {
     /// # #![allow(unused_must_use)]
     /// use std::ffi::{CString};
     ///
-    /// let ptr = CString::new("Hello").unwrap().as_ptr();
+    /// let ptr = CString::new("Hello").expect("CString::new failed").as_ptr();
     /// unsafe {
     ///     // `ptr` is dangling
     ///     *ptr;
@@ -1067,14 +1069,14 @@ impl CStr {
     ///
     /// This happens because the pointer returned by `as_ptr` does not carry any
     /// lifetime information and the [`CString`] is deallocated immediately after
-    /// the `CString::new("Hello").unwrap().as_ptr()` expression is evaluated.
+    /// the `CString::new("Hello").expect("CString::new failed").as_ptr()` expression is evaluated.
     /// To fix the problem, bind the `CString` to a local variable:
     ///
     /// ```no_run
     /// # #![allow(unused_must_use)]
     /// use std::ffi::{CString};
     ///
-    /// let hello = CString::new("Hello").unwrap();
+    /// let hello = CString::new("Hello").expect("CString::new failed");
     /// let ptr = hello.as_ptr();
     /// unsafe {
     ///     // `ptr` is valid because `hello` is in scope
@@ -1106,7 +1108,7 @@ impl CStr {
     /// ```
     /// use std::ffi::CStr;
     ///
-    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
+    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(c_str.to_bytes(), b"foo");
     /// ```
     #[inline]
@@ -1132,7 +1134,7 @@ impl CStr {
     /// ```
     /// use std::ffi::CStr;
     ///
-    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
+    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(c_str.to_bytes_with_nul(), b"foo\0");
     /// ```
     #[inline]
@@ -1159,7 +1161,7 @@ impl CStr {
     /// ```
     /// use std::ffi::CStr;
     ///
-    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
+    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(c_str.to_str(), Ok("foo"));
     /// ```
     #[stable(feature = "cstr_to_str", since = "1.4.0")]
@@ -1200,7 +1202,8 @@ impl CStr {
     /// use std::borrow::Cow;
     /// use std::ffi::CStr;
     ///
-    /// let c_str = CStr::from_bytes_with_nul(b"Hello World\0").unwrap();
+    /// let c_str = CStr::from_bytes_with_nul(b"Hello World\0")
+    ///                  .expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(c_str.to_string_lossy(), Cow::Borrowed("Hello World"));
     /// ```
     ///
@@ -1210,7 +1213,8 @@ impl CStr {
     /// use std::borrow::Cow;
     /// use std::ffi::CStr;
     ///
-    /// let c_str = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0").unwrap();
+    /// let c_str = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0")
+    ///                  .expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(
     ///     c_str.to_string_lossy(),
     ///     Cow::Owned(String::from("Hello �World")) as Cow<str>
@@ -1231,9 +1235,9 @@ impl CStr {
     /// ```
     /// use std::ffi::CString;
     ///
-    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
+    /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
     /// let boxed = c_string.into_boxed_c_str();
-    /// assert_eq!(boxed.into_c_string(), CString::new("foo").unwrap());
+    /// assert_eq!(boxed.into_c_string(), CString::new("foo").expect("CString::new failed"));
     /// ```
     #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
     pub fn into_c_string(self: Box<CStr>) -> CString {