Replace old GDB and LLDB pretty-printers with new ones
which were originally written for IntelliJ Rust.
New LLDB pretty-printers support synthetic children.
New GDB/LLDB pretty-printers support all Rust types
supported by old pretty-printers, and also support:
Rc, Arc, Cell, Ref, RefCell, RefMut, HashMap, HashSet.
We're shipping a rust-enabled lldb, but the "lldb" executable is not
installed into the "bin" directory by rustup. See the discussion in
https://github.com/rust-lang-nursery/rustup.rs/pull/1492 for
background on this decision. There, we agreed to have rust-lldb
prefer the rust-enabled lldb if it is installed.
This patch changes dist.rs to put lldb into rustlib, following what
was done for the other LLVM tools in #53955, and then fixes rust-lldb
to prefer that lldb, if it exists.
See issue #48168
This way the process we get by calling rust-{gdb,lldb} is an actual
{gdb,lldb} instance and not (perhaps surprisingly) a script waiting for
the debugger process to finish. Thus, sending a SIGINT to the spawned
process stops execution of the child, for example.
This commit shuffles around some CLI flags of the compiler to some more stable
locations with some renamings. The changes made were:
* The `-v` flag has been repurposes as the "verbose" flag. The version flag has
been renamed to `-V`.
* The `-h` screen has been split into two parts. Most top-level options (not
all) show with `-h`, and the remaining options (generally obscure) can be
shown with `--help -v` which is a "verbose help screen"
* The `-V` flag (version flag now) has lost its argument as it is now requested
with `rustc -vV` "verbose version".
* The `--emit` option has had its `ir` and `bc` variants renamed to `llvm-ir`
and `llvm-bc` to emphasize that they are LLVM's IR/bytecode.
* The `--emit` option has grown a new variant, `dep-info`, which subsumes the
`--dep-info` CLI argument. The `--dep-info` flag is now deprecated.
* The `--parse-only`, `--no-trans`, and `--no-analysis` flags have
moved behind the `-Z` family of flags.
* The `--debuginfo` and `--opt-level` flags were moved behind the top-level `-C`
flag.
* The `--print-file-name` and `--print-crate-name` flags were moved behind one
global `--print` flag which now accepts one of `crate-name`, `file-names`, or
`sysroot`. This global `--print` flag is intended to serve as a mechanism for
learning various metadata about the compiler itself.
No warnings are currently enabled to allow tools like Cargo to have time to
migrate to the new flags before spraying warnings to all users.