diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 9481cd4e1a4f..fc0a3c0fd881 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -1328,7 +1328,7 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Arc<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> fmt::Pointer for Arc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Pointer::fmt(&self.ptr, f)
+        fmt::Pointer::fmt(&(&**self as *const T), f)
     }
 }
 
diff --git a/src/liballoc/fmt.rs b/src/liballoc/fmt.rs
index 58299d5d8361..77f65412bd3e 100644
--- a/src/liballoc/fmt.rs
+++ b/src/liballoc/fmt.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Utilities for formatting and printing `String`s
+//! Utilities for formatting and printing `String`s.
 //!
 //! This module contains the runtime support for the [`format!`] syntax extension.
 //! This macro is implemented in the compiler to emit calls to this module in
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 2f8620cc7505..72b9fa0eb472 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -1072,7 +1072,7 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Rc<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> fmt::Pointer for Rc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Pointer::fmt(&self.ptr, f)
+        fmt::Pointer::fmt(&(&**self as *const T), f)
     }
 }
 
diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs
index f68ee847eb3a..6e8515f0b362 100644
--- a/src/liballoc/str.rs
+++ b/src/liballoc/str.rs
@@ -1734,7 +1734,7 @@ impl str {
     /// A more complex pattern, using a closure:
     ///
     /// ```
-    /// assert_eq!("1fooX".trim_left_matches(|c| c == '1' || c == 'X'), "fooX");
+    /// assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn trim_right_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str
diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index c410c2d90047..122baec8e58d 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -361,7 +361,7 @@ macro_rules! try {
     })
 }
 
-/// Write formatted data into a buffer
+/// Write formatted data into a buffer.
 ///
 /// This macro accepts a format string, a list of arguments, and a 'writer'. Arguments will be
 /// formatted according to the specified format string and the result will be passed to the writer.
diff --git a/src/librustc_mir/borrow_check.rs b/src/librustc_mir/borrow_check.rs
index cdac72b6dffb..ec173ef66f63 100644
--- a/src/librustc_mir/borrow_check.rs
+++ b/src/librustc_mir/borrow_check.rs
@@ -91,7 +91,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
                     IllegalMoveOriginKind::Static =>
                         tcx.cannot_move_out_of(span, "static item", origin),
                     IllegalMoveOriginKind::BorrowedContent =>
-                        tcx.cannot_move_out_of(span, "borrowed_content", origin),
+                        tcx.cannot_move_out_of(span, "borrowed content", origin),
                     IllegalMoveOriginKind::InteriorOfTypeWithDestructor { container_ty: ty } =>
                         tcx.cannot_move_out_of_interior_of_drop(span, ty, origin),
                     IllegalMoveOriginKind::InteriorOfSliceOrArray { ty, is_index } =>
diff --git a/src/libstd/f32.rs b/src/libstd/f32.rs
index 14f0edc36905..645a4c211509 100644
--- a/src/libstd/f32.rs
+++ b/src/libstd/f32.rs
@@ -9,8 +9,9 @@
 // except according to those terms.
 
 //! This module provides constants which are specific to the implementation
-//! of the `f32` floating point data type. Mathematically significant
-//! numbers are provided in the `consts` sub-module.
+//! of the `f32` floating point data type.
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 //!
 //! *[See also the `f32` primitive type](../primitive.f32.html).*
 
diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs
index e0f0acc6ac44..7fd798155bd5 100644
--- a/src/libstd/f64.rs
+++ b/src/libstd/f64.rs
@@ -9,8 +9,9 @@
 // except according to those terms.
 
 //! This module provides constants which are specific to the implementation
-//! of the `f64` floating point data type. Mathematically significant
-//! numbers are provided in the `consts` sub-module.
+//! of the `f64` floating point data type.
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 //!
 //! *[See also the `f64` primitive type](../primitive.f64.html).*
 
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 57f8c39756e3..62313d7d3a6e 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -419,14 +419,8 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
 ///
 /// [`File`]s implement `Read`:
 ///
-/// [`read()`]: trait.Read.html#tymethod.read
-/// [`std::io`]: ../../std/io/index.html
-/// [`File`]: ../fs/struct.File.html
-/// [`BufRead`]: trait.BufRead.html
-/// [`BufReader`]: struct.BufReader.html
-///
 /// ```
-/// use std::io;
+/// # use std::io;
 /// use std::io::prelude::*;
 /// use std::fs::File;
 ///
@@ -449,6 +443,32 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
 /// # Ok(())
 /// # }
 /// ```
+///
+/// Read from `&str` because [`&[u8]`] implements [`Read`]:
+///
+/// ```
+/// # use std::io;
+/// use std::io::prelude::*;
+///
+/// # fn foo() -> io::Result<()> {
+/// let mut b = "This string will be read".as_bytes();
+/// let mut buffer = [0; 10];
+///
+/// // read up to 10 bytes
+/// b.read(&mut buffer)?;
+///
+/// // etc... it works exactly as a File does!
+/// # Ok(())
+/// # }
+/// ```
+///
+/// [`read()`]: trait.Read.html#tymethod.read
+/// [`std::io`]: ../../std/io/index.html
+/// [`File`]: ../fs/struct.File.html
+/// [`BufRead`]: trait.BufRead.html
+/// [`BufReader`]: struct.BufReader.html
+/// [`&[u8]`]: primitive.slice.html
+///
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Read {
     /// Pull some bytes from this source into the specified buffer, returning
diff --git a/src/libstd/panic.rs b/src/libstd/panic.rs
index 385076e50dde..219e55d6c120 100644
--- a/src/libstd/panic.rs
+++ b/src/libstd/panic.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Panic support in the standard library
+//! Panic support in the standard library.
 
 #![stable(feature = "std_panic", since = "1.9.0")]
 
diff --git a/src/libstd/sync/mutex.rs b/src/libstd/sync/mutex.rs
index eb507858b92b..81f5594bc523 100644
--- a/src/libstd/sync/mutex.rs
+++ b/src/libstd/sync/mutex.rs
@@ -382,6 +382,17 @@ unsafe impl<#[may_dangle] T: ?Sized> Drop for Mutex<T> {
     }
 }
 
+#[stable(feature = "mutex_from", since = "1.22.0")]
+impl<T> From<T> for Mutex<T> {
+    /// Creates a new mutex in an unlocked state ready for use.
+    /// This is equivalent to [`Mutex::new`].
+    ///
+    /// [`Mutex::new`]: #method.new
+    fn from(t: T) -> Self {
+        Mutex::new(t)
+    }
+}
+
 #[stable(feature = "mutex_default", since = "1.10.0")]
 impl<T: ?Sized + Default> Default for Mutex<T> {
     /// Creates a `Mutex<T>`, with the `Default` value for T.
diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
index 6216d78528db..fd6cff6b69c4 100644
--- a/src/libstd/sync/rwlock.rs
+++ b/src/libstd/sync/rwlock.rs
@@ -457,6 +457,17 @@ impl<T: Default> Default for RwLock<T> {
     }
 }
 
+#[stable(feature = "rw_lock_from", since = "1.22.0")]
+impl<T> From<T> for RwLock<T> {
+    /// Creates a new instance of an `RwLock<T>` which is unlocked.
+    /// This is equivalent to [`RwLock::new`].
+    ///
+    /// [`RwLock::new`]: #method.new
+    fn from(t: T) -> Self {
+        RwLock::new(t)
+    }
+}
+
 impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> {
     unsafe fn new(lock: &'rwlock RwLock<T>)
                   -> LockResult<RwLockReadGuard<'rwlock, T>> {
diff --git a/src/libstd/sys/redox/os.rs b/src/libstd/sys/redox/os.rs
index c27e2ee172c6..480765b77a02 100644
--- a/src/libstd/sys/redox/os.rs
+++ b/src/libstd/sys/redox/os.rs
@@ -213,3 +213,7 @@ pub fn exit(code: i32) -> ! {
 pub fn getpid() -> u32 {
     syscall::getpid().unwrap() as u32
 }
+
+pub fn getppid() -> u32 {
+    syscall::getppid().unwrap() as u32
+}
diff --git a/src/libstd/sys/unix/ext/process.rs b/src/libstd/sys/unix/ext/process.rs
index cde21b089a20..60309bec6d4f 100644
--- a/src/libstd/sys/unix/ext/process.rs
+++ b/src/libstd/sys/unix/ext/process.rs
@@ -191,3 +191,9 @@ impl IntoRawFd for process::ChildStderr {
         self.into_inner().into_fd().into_raw()
     }
 }
+
+/// Returns the OS-assigned process identifier associated with this process's parent.
+#[unstable(feature = "unix_ppid", issue = "46104")]
+pub fn parent_id() -> u32 {
+    ::sys::os::getppid()
+}
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 40b73f1b3070..7e965b4b4c5b 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -515,3 +515,7 @@ pub fn exit(code: i32) -> ! {
 pub fn getpid() -> u32 {
     unsafe { libc::getpid() as u32 }
 }
+
+pub fn getppid() -> u32 {
+    unsafe { libc::getppid() as u32 }
+}
diff --git a/src/rustllvm/ArchiveWrapper.cpp b/src/rustllvm/ArchiveWrapper.cpp
index 7f76861c0777..591ebdc9ddb2 100644
--- a/src/rustllvm/ArchiveWrapper.cpp
+++ b/src/rustllvm/ArchiveWrapper.cpp
@@ -66,7 +66,7 @@ static Archive::Kind fromRust(LLVMRustArchiveKind Kind) {
   case LLVMRustArchiveKind::COFF:
     return Archive::K_COFF;
   default:
-    llvm_unreachable("Bad ArchiveKind.");
+    report_fatal_error("Bad ArchiveKind.");
   }
 }
 
diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index d0c042e6451c..4a359fb3ad30 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -235,7 +235,7 @@ static CodeModel::Model fromRust(LLVMRustCodeModel Model) {
   case LLVMRustCodeModel::Large:
     return CodeModel::Large;
   default:
-    llvm_unreachable("Bad CodeModel.");
+    report_fatal_error("Bad CodeModel.");
   }
 }
 
@@ -258,7 +258,7 @@ static CodeGenOpt::Level fromRust(LLVMRustCodeGenOptLevel Level) {
   case LLVMRustCodeGenOptLevel::Aggressive:
     return CodeGenOpt::Aggressive;
   default:
-    llvm_unreachable("Bad CodeGenOptLevel.");
+    report_fatal_error("Bad CodeGenOptLevel.");
   }
 }
 
@@ -302,7 +302,7 @@ static Optional<Reloc::Model> fromRust(LLVMRustRelocMode RustReloc) {
     break;
 #endif
   }
-  llvm_unreachable("Bad RelocModel.");
+  report_fatal_error("Bad RelocModel.");
 }
 
 #if LLVM_RUSTLLVM
@@ -511,7 +511,7 @@ static TargetMachine::CodeGenFileType fromRust(LLVMRustFileType Type) {
   case LLVMRustFileType::ObjectFile:
     return TargetMachine::CGFT_ObjectFile;
   default:
-    llvm_unreachable("Bad FileType.");
+    report_fatal_error("Bad FileType.");
   }
 }
 
@@ -1197,7 +1197,7 @@ extern "C" bool
 LLVMRustWriteThinBitcodeToFile(LLVMPassManagerRef PMR,
                                LLVMModuleRef M,
                                const char *BcFile) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 struct LLVMRustThinLTOData {
@@ -1211,32 +1211,32 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
                           int num_modules,
                           const char **preserved_symbols,
                           int num_symbols) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" bool
 LLVMRustPrepareThinLTORename(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" bool
 LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" bool
 LLVMRustPrepareThinLTOInternalize(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" bool
 LLVMRustPrepareThinLTOImport(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" void
 LLVMRustFreeThinLTOData(LLVMRustThinLTOData *Data) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 struct LLVMRustThinLTOBuffer {
@@ -1244,22 +1244,22 @@ struct LLVMRustThinLTOBuffer {
 
 extern "C" LLVMRustThinLTOBuffer*
 LLVMRustThinLTOBufferCreate(LLVMModuleRef M) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" void
 LLVMRustThinLTOBufferFree(LLVMRustThinLTOBuffer *Buffer) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" const void*
 LLVMRustThinLTOBufferPtr(const LLVMRustThinLTOBuffer *Buffer) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" size_t
 LLVMRustThinLTOBufferLen(const LLVMRustThinLTOBuffer *Buffer) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 
 extern "C" LLVMModuleRef
@@ -1267,6 +1267,6 @@ LLVMRustParseBitcodeForThinLTO(LLVMContextRef Context,
                                const char *data,
                                size_t len,
                                const char *identifier) {
-  llvm_unreachable("ThinLTO not available");
+  report_fatal_error("ThinLTO not available");
 }
 #endif // LLVM_VERSION_GE(4, 0)
diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 9aa172591b86..424b226bcf77 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -54,7 +54,7 @@ static AtomicOrdering fromRust(LLVMAtomicOrdering Ordering) {
     return AtomicOrdering::SequentiallyConsistent;
   }
 
-  llvm_unreachable("Invalid LLVMAtomicOrdering value!");
+  report_fatal_error("Invalid LLVMAtomicOrdering value!");
 }
 
 static LLVM_THREAD_LOCAL char *LastError;
@@ -161,7 +161,7 @@ static Attribute::AttrKind fromRust(LLVMRustAttribute Kind) {
   case SanitizeMemory:
     return Attribute::SanitizeMemory;
   }
-  llvm_unreachable("bad AttributeKind");
+  report_fatal_error("bad AttributeKind");
 }
 
 extern "C" void LLVMRustAddCallSiteAttribute(LLVMValueRef Instr, unsigned Index,
@@ -356,7 +356,7 @@ static SyncScope::ID fromRust(LLVMRustSynchronizationScope Scope) {
   case LLVMRustSynchronizationScope::CrossThread:
     return SyncScope::System;
   default:
-    llvm_unreachable("bad SynchronizationScope.");
+    report_fatal_error("bad SynchronizationScope.");
   }
 }
 #else
@@ -367,7 +367,7 @@ static SynchronizationScope fromRust(LLVMRustSynchronizationScope Scope) {
   case LLVMRustSynchronizationScope::CrossThread:
     return CrossThread;
   default:
-    llvm_unreachable("bad SynchronizationScope.");
+    report_fatal_error("bad SynchronizationScope.");
   }
 }
 #endif
@@ -397,7 +397,7 @@ static InlineAsm::AsmDialect fromRust(LLVMRustAsmDialect Dialect) {
   case LLVMRustAsmDialect::Intel:
     return InlineAsm::AD_Intel;
   default:
-    llvm_unreachable("bad AsmDialect.");
+    report_fatal_error("bad AsmDialect.");
   }
 }
 
@@ -748,7 +748,7 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateVariable(
         unwrapDI<DIType>(Ty), AlwaysPreserve, fromRust(Flags)
 #if LLVM_VERSION_GE(4, 0)
         ,
-	AlignInBits
+  AlignInBits
 #endif
         ));
   } else {
@@ -1149,7 +1149,7 @@ extern "C" LLVMTypeKind LLVMRustGetTypeKind(LLVMTypeRef Ty) {
     return LLVMTokenTypeKind;
 #endif
   }
-  llvm_unreachable("Unhandled TypeID.");
+  report_fatal_error("Unhandled TypeID.");
 }
 
 extern "C" void LLVMRustWriteDebugLocToString(LLVMContextRef C,
@@ -1370,7 +1370,7 @@ static LLVMRustLinkage toRust(LLVMLinkage Linkage) {
   case LLVMCommonLinkage:
     return LLVMRustLinkage::CommonLinkage;
   default:
-    llvm_unreachable("Invalid LLVMRustLinkage value!");
+    report_fatal_error("Invalid LLVMRustLinkage value!");
   }
 }
 
@@ -1399,7 +1399,7 @@ static LLVMLinkage fromRust(LLVMRustLinkage Linkage) {
   case LLVMRustLinkage::CommonLinkage:
     return LLVMCommonLinkage;
   }
-  llvm_unreachable("Invalid LLVMRustLinkage value!");
+  report_fatal_error("Invalid LLVMRustLinkage value!");
 }
 
 extern "C" LLVMRustLinkage LLVMRustGetLinkage(LLVMValueRef V) {
@@ -1447,7 +1447,7 @@ static LLVMRustVisibility toRust(LLVMVisibility Vis) {
   case LLVMProtectedVisibility:
     return LLVMRustVisibility::Protected;
   }
-  llvm_unreachable("Invalid LLVMRustVisibility value!");
+  report_fatal_error("Invalid LLVMRustVisibility value!");
 }
 
 static LLVMVisibility fromRust(LLVMRustVisibility Vis) {
@@ -1459,7 +1459,7 @@ static LLVMVisibility fromRust(LLVMRustVisibility Vis) {
   case LLVMRustVisibility::Protected:
     return LLVMProtectedVisibility;
   }
-  llvm_unreachable("Invalid LLVMRustVisibility value!");
+  report_fatal_error("Invalid LLVMRustVisibility value!");
 }
 
 extern "C" LLVMRustVisibility LLVMRustGetVisibility(LLVMValueRef V) {
diff --git a/src/test/COMPILER_TESTS.md b/src/test/COMPILER_TESTS.md
index 0380454b8278..0bc29e8b5aa9 100644
--- a/src/test/COMPILER_TESTS.md
+++ b/src/test/COMPILER_TESTS.md
@@ -106,7 +106,7 @@ result is then compared against reference files named
 those files doesn't exist, the output must be empty. If the test run
 fails, we will print out the current output, but it is also saved in
 `build/<target-triple>/test/ui/hello_world/main.stdout` (this path is
-printed as part of the test failure mesage), so you can run `diff` and
+printed as part of the test failure message), so you can run `diff` and
 so forth.
 
 ### Editing and updating the reference files
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 598620fa2939..bd49f288eb2e 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -57,7 +57,6 @@ fn filter_dirs(path: &Path) -> bool {
         "src/libbacktrace",
         "src/libcompiler_builtins",
         "src/compiler-rt",
-        "src/rustllvm",
         "src/liblibc",
         "src/vendor",
         "src/rt/hoedown",
diff --git a/src/tools/tidy/src/style.rs b/src/tools/tidy/src/style.rs
index a689d8a8be41..40d84b98d3a7 100644
--- a/src/tools/tidy/src/style.rs
+++ b/src/tools/tidy/src/style.rs
@@ -50,6 +50,11 @@ const UNEXPLAINED_IGNORE_DOCTEST_INFO: &str = r#"unexplained "```ignore" doctest
 
 "#;
 
+const LLVM_UNREACHABLE_INFO: &str = r"\
+C++ code used llvm_unreachable, which triggers undefined behavior
+when executed when assertions are disabled.
+Use llvm::report_fatal_error for increased robustness.";
+
 /// Parser states for line_is_url.
 #[derive(PartialEq)]
 #[allow(non_camel_case_types)]
@@ -108,7 +113,7 @@ pub fn check(path: &Path, bad: &mut bool) {
     let mut contents = String::new();
     super::walk(path, &mut super::filter_dirs, &mut |file| {
         let filename = file.file_name().unwrap().to_string_lossy();
-        let extensions = [".rs", ".py", ".js", ".sh", ".c", ".h"];
+        let extensions = [".rs", ".py", ".js", ".sh", ".c", ".cpp", ".h"];
         if extensions.iter().all(|e| !filename.ends_with(e)) ||
            filename.starts_with(".#") {
             return
@@ -153,6 +158,9 @@ pub fn check(path: &Path, bad: &mut bool) {
             if line.ends_with("```ignore") || line.ends_with("```rust,ignore") {
                 err(UNEXPLAINED_IGNORE_DOCTEST_INFO);
             }
+            if filename.ends_with(".cpp") && line.contains("llvm_unreachable") {
+                err(LLVM_UNREACHABLE_INFO);
+            }
         }
         if !licenseck(file, &contents) {
             tidy_error!(bad, "{}: incorrect license", file.display());