Unwrap the panic chapter

Per the style guide, lines should not be wrapped.

Author: ehuss

src/panic.md

@@ -3,118 +3,72 @@
 r[panic]
 
 r[panic.intro]
-Rust provides a mechanism to prevent a function from returning normally, and
-instead "panic," which is a response to an error condition that is typically
-not expected to be recoverable within the context in which the error is
-encountered.
+Rust provides a mechanism to prevent a function from returning normally, and instead "panic," which is a response to an error condition that is typically not expected to be recoverable within the context in which the error is encountered.
 
 r[panic.lang-ops]
-Some language constructs, such as out-of-bounds [array indexing], panic
-automatically.
+Some language constructs, such as out-of-bounds [array indexing], panic automatically.
 
 r[panic.control]
-There are also language features that provide a level of control
-over panic behavior:
-* A [_panic runtime_](#panic-runtimes) defined how a panic is handled during
-  runtime.
+There are also language features that provide a level of control over panic behavior:
+
+* A [_panic runtime_](#panic-runtimes) defined how a panic is handled during runtime.
 * [FFI ABIs](items/functions.md#unwinding) may alter how panics behave.
 
 > [!NOTE]
-> The standard library provides the capability to explicitly panic
-> via the [`panic!` macro][panic!].
+> The standard library provides the capability to explicitly panic via the [`panic!` macro][panic!].
 
 ## Unwinding
 
 r[panic.unwind]
 
 r[panic.unwind.intro]
-Panicking may either be recoverable or non-recoverable, though it can be
-configured (via `panic=abort`) to always be non-recoverable. (The converse is
-not true: `panic=unwind` does not guarantee that all panics are recoverable,
-only that panicking via the `panic!` macro and similar standard library
-mechanisms is recoverable.)
+Panicking may either be recoverable or non-recoverable, though it can be configured (via `panic=abort`) to always be non-recoverable. (The converse is not true: `panic=unwind` does not guarantee that all panics are recoverable, only that panicking via the `panic!` macro and similar standard library mechanisms is recoverable.)
 
 r[panic.unwind.destruction]
-When panic recovery occurs, the runtime "unwinds" Rust frames, just as C++'s `throw` unwinds C++ frames, until the panic reaches
-the point of recovery (for instance at a thread boundary). This means that as
-the panic traverses Rust frames, live objects in those frames that [implement
-`Drop`][destructors] will have their `drop` methods called. Thus, when normal
-execution resumes, no-longer-accessible objects will have been "cleaned up"
-just as if they had gone out of scope normally.
+When panic recovery occurs, the runtime "unwinds" Rust frames, just as C++'s `throw` unwinds C++ frames, until the panic reaches the point of recovery (for instance at a thread boundary). This means that as the panic traverses Rust frames, live objects in those frames that [implement `Drop`][destructors] will have their `drop` methods called. Thus, when normal execution resumes, no-longer-accessible objects will have been "cleaned up" just as if they had gone out of scope normally.
 
 > [!NOTE]
-> As long as this guarantee of resource-cleanup is preserved,
-> "unwinding" may be implemented without actually using the mechanism used by
-> C++ for the target platform.
+> As long as this guarantee of resource-cleanup is preserved, "unwinding" may be implemented without actually using the mechanism used by C++ for the target platform.
 
 > [!NOTE]
-> The standard library provides two mechanisms for recovering from a panic,
-> [`std::panic::catch_unwind`] (which enables recovery within the
-> panicking thread) and [`std::thread::spawn`] (which automatically
-> sets up panic recovery for the spawned thread so that other threads may
-> continue running).
+> The standard library provides two mechanisms for recovering from a panic, [`std::panic::catch_unwind`] (which enables recovery within the panicking thread) and [`std::thread::spawn`] (which automatically sets up panic recovery for the spawned thread so that other threads may continue running).
 
 ### Unwinding across FFI boundaries
 
 r[panic.unwind.ffi]
 
 r[panic.unwind.ffi.intro]
-It is possible to unwind across FFI boundaries using an [appropriate ABI
-declaration][unwind-abi]. While useful in certain cases, this creates unique
-opportunities for undefined behavior, especially when multiple language runtimes
-are involved.
+It is possible to unwind across FFI boundaries using an [appropriate ABI declaration][unwind-abi]. While useful in certain cases, this creates unique opportunities for undefined behavior, especially when multiple language runtimes are involved.
 
 r[panic.unwind.ffi.undefined]
 Unwinding with the wrong ABI is undefined behavior:
 
-* Causing an unwind into Rust code from a foreign function that was called via a
-  function declaration or pointer declared with a non-unwinding ABI, such as `"C"`,
-  `"system"`, etc. (For example, this case occurs when such a function written in
-  C++ throws an exception that is uncaught and propagates to Rust.)
-* Calling a Rust `extern` function that unwinds (with `extern "C-unwind"` or
-  another ABI that permits unwinding) from a runtime that does not support.
-  unwinding, such as code compiled with GCC or Clang using `-fno-exceptions`
+* Causing an unwind into Rust code from a foreign function that was called via a function declaration or pointer declared with a non-unwinding ABI, such as `"C"`, `"system"`, etc. (For example, this case occurs when such a function written in C++ throws an exception that is uncaught and propagates to Rust.)
+* Calling a Rust `extern` function that unwinds (with `extern "C-unwind"` or another ABI that permits unwinding) from a runtime that does not support. unwinding, such as code compiled with GCC or Clang using `-fno-exceptions`
 
 r[panic.unwind.ffi.catch-foreign]
-Catching a foreign unwinding operation (such as a C++ exception) using
-[`std::panic::catch_unwind`], [`std::thread::JoinHandle::join`], or by letting it propagate beyond the
-Rust `main()` function or thread root will have one of two behaviors, and it is unspecified
-which will occur:
+Catching a foreign unwinding operation (such as a C++ exception) using [`std::panic::catch_unwind`], [`std::thread::JoinHandle::join`], or by letting it propagate beyond the Rust `main()` function or thread root will have one of two behaviors, and it is unspecified which will occur:
+
 * The process aborts.
 * The function returns a [`Result::Err`] containing an opaque type.
 
 > [!NOTE]
->  Rust code compiled or linked with a different instance of the Rust runtime counts as a
-> "foreign exception" for the purpose of this guarantee. Thus, a library that
-> uses `panic!` and is linked against one version of the Rust standard library,
-> invoked from an application that uses a different version of the standard
-> library, may cause the entire application to crash even if the library is only
-> used within a child thread.
+>  Rust code compiled or linked with a different instance of the Rust runtime counts as a "foreign exception" for the purpose of this guarantee. Thus, a library that uses `panic!` and is linked against one version of the Rust standard library, invoked from an application that uses a different version of the standard library, may cause the entire application to crash even if the library is only used within a child thread.
 
 r[panic.unwind.ffi.dispose-panic]
-There are currently no guarantees about the behavior that occurs when a foreign
-runtime attempts to dispose of, or rethrow, a Rust `panic` payload. In other
-words, an unwind originated from a Rust runtime must either lead to termination
-of the process or be caught by the same runtime.
+There are currently no guarantees about the behavior that occurs when a foreign runtime attempts to dispose of, or rethrow, a Rust `panic` payload. In other words, an unwind originated from a Rust runtime must either lead to termination of the process or be caught by the same runtime.
 
 ## Panic runtimes
 
 r[panic.runtime]
 
-The actual behavior and implementation of `panic!` is controlled by the _panic
-runtime_.
+The actual behavior and implementation of `panic!` is controlled by the _panic runtime_.
 
 > [!NOTE]
-> The Rust standard library provides two panic runtimes:
-> `panic_unwind` (which unwinds the stack and is potentially recoverable) and
-> `panic_abort` (which aborts the process and is non-recoverable). The default
-> runtime depends on the target platform, but is generally `panic_unwind` on
-> platforms with native support for C++ exceptions.
+> The Rust standard library provides two panic runtimes: `panic_unwind` (which unwinds the stack and is potentially recoverable) and `panic_abort` (which aborts the process and is non-recoverable). The default runtime depends on the target platform, but is generally `panic_unwind` on platforms with native support for C++ exceptions.
 
 > [!NOTE]
-> When compiling code that is guaranteed to be linked to a non-recoverable panic
-> runtime, the optimizer may assume that unwinding across Rust frames is
-> impossible, which can result in both code-size and runtime speed improvements.
+> When compiling code that is guaranteed to be linked to a non-recoverable panic runtime, the optimizer may assume that unwinding across Rust frames is impossible, which can result in both code-size and runtime speed improvements.
 
 See also the [`panic_handler` attribute](runtime.md#the-panic_handler-attribute) which can be used to change the behavior of panics.