Currently, the format_args!() macro takes as its first argument an expression
which is the callee of an ExprCall. This means that if format_args!() is used
with calling a method a closure must be used. Consider this code, however:
format_args!(|args| { foo.writer.write_fmt(args) }, "{}", foo.field)
The closure borrows the entire `foo` structure, disallowing the later borrow of
`foo.field`. To preserve the semantics of the `write!` macro, it is also
impossible to borrow specifically the `writer` field of the `foo` structure
because it must be borrowed mutably, but the `foo` structure is not guaranteed
to be mutable itself.
This new macro is invoked like:
format_args_method!(foo.writer, write_fmt, "{}", foo.field)
This macro will generate an ExprMethodCall which allows the borrow checker to
understand that `writer` and `field` should be borrowed separately.
This macro is not strictly necessary, with DST or possibly UFCS other
workarounds could be used. For now, though, it looks like this is required to
implement the `write!` macro.
This new method, write_fmt(), is the one way to write a formatted list of
arguments into a Writer stream. This has a special adaptor to preserve errors
which occur on the writer.
All macros will be updated to use this method explicitly.
Now that std::fmt is in libcore, it's possible to implement this as an inherit
method rather than through extension traits.
This commit also tweaks the failure interface of libcore to libstd to what it
should be, one method taking &fmt::Arguments
This commit moves all possible functionality from the standard library's string
formatting utilities into the core library. This is a breaking change, due to a
few tweaks in the semantics of formatting:
1. In order to break the dependency on the std::io module, a new trait,
FormatWriter was introduced in core::fmt. This is the trait which is used
(instead of Writer) to format data into a stream.
2. The new FormatWriter trait has one method, write(), which takes some bytes
and can return an error, but the error contains very little information. The
intent for this trait is for an adaptor writer to be used around the standard
library's Writer trait.
3. The fmt::write{,ln,_unsafe} methods no longer take &mut io::Writer, but
rather &mut FormatWriter. Since this trait is less common, all functions were
removed except fmt::write, and it is not intended to be invoked directly.
The main API-breaking change here is that the fmt::Formatter structure will no
longer expose its `buf` field. All previous code writing directly to `f.buf`
using writer methods or the `write!` macro will now instead use `f` directly.
The Formatter object itself implements the `Writer` trait itself for
convenience, although it does not implement the `FormatWriter` trait. The
fallout of these changes will be in the following commits.
[breaking-change]
The Float trait in libstd is quite a large trait which has dependencies on cmath
(libm) and such, which libcore cannot satisfy. It also has many functions that
libcore can implement, however, as LLVM has intrinsics or they're just bit
twiddling.
This commit moves what it can of the Float trait from the standard library into
libcore to allow floats to be usable in the core library. The remaining
functions are now resident in a FloatMath trait in the standard library (in the
prelude now). Previous code which was generic over just the Float trait may now
need to be generic over the FloatMath trait.
[breaking-change]
This used to be called `mangle` and was removed when the Robin Hood hash map came along, but it is a useful thing to have in certain situations (I just hit it with my Teepee header representation), so I want it back.
The method is renamed to `find_with_or_insert_with`, also with the parameters swapped to make sense—find and then insert, not insert and then find.
/cc @cgaebel
Closes#14231 (mk: Don't run benchmarks with `make check`)
Closes#14215 (std: Modify TempDir to not fail on drop. Closes#12628)
Closes#14211 (rustdoc: functions in ffi blocks are unsafe)
Closes#14210 (Make Vec.truncate() resilient against failure in Drop)
Closes#14208 (Make `from_bits` in `bitflags!` safe; add `from_bits_truncate`)
Closes#14206 (Register new snapshots)
Closes#14205 (use sched_yield on linux and freebsd)
Closes#14204 (Add a crate for missing stubs from libcore)
Closes#14203 (shootout-mandelbrot: Either 10-20% or 80-100% improvement.)
Closes#14202 (Add flow-graph visualization (via graphviz) to rustc)
Closes#14201 (Render not_found with an absolute path to the rust stylesheet)
Closes#14200 (std cleanup)
Closes#14189 (Implement cell::clone_ref)
Each test works by rendering the flowgraph for the last identified
block we see in expanded pretty-printed output, and comparing it (via
`diff`) against a checked in "foo.dot-expected.dot" file.
Each test post-processes the output to remove NodeIds ` (id=NUM)` so
that the expected output is somewhat stable (or at least independent
of how we assign NodeIds) and easier for a human to interpret when
looking at the expected output file itself.
----
Test writing style notes:
I usually tried to write the tests in a way that would avoid duplicate
labels in the output rendered flow graph, when possible.
The tests that have string literals "unreachable" in the program text
are deliberately written that way to remind the reader that the
unreachable nodes in the resulting graph are not an error in the
control flow computation, but rather a natural consequence of its
construction.
Passing `--pretty flowgraph=<NODEID>` makes rustc print a control flow graph.
In pratice, you will also need to pass the additional option:
`-o <FILE>` to emit output to a `.dot` file for graphviz.
(You can only print the flow-graph for a particular block in the AST.)
----
An interesting implementation detail is the way the code puts both the
node index (`cfg::CFGIndex`) and a reference to the payload
(`cfg::CFGNode`) into the single `Node` type that is used for
labelling and walking the graph. I had once mistakenly thought that I
only wanted the `cfg::CFGNode`, but for labelling, you really want the
cfg index too, rather than e.g. trying to use the `ast::NodeId` as the
label (which breaks down e.g. due to `ast::DUMMY_NODE_ID`).
----
As a drive-by fix, I had to fix `rustc::middle::cfg::construct`
interface to reflect changes that have happened on the master branch
while I was getting this integrated into the compiler. (The next
commit actually adds tests of the `--pretty flowgraph` functionality,
so that should ensure that the `rustc::middle::cfg` code does not go
stale again.)
1. Only insert non-dummy nodes into the exit map.
2. Revise handling of `break` and `continue` forms so that they are
not treated as if control falls through to the next node (since it
does not, it just jumps to the end or start of the loop body).
3. Fixed support for return expression in flow graph construction.
Refine lifetimes in signature for graph node/edge iteration methods.
Added `pub` `node_id` and `edge_id` methods that correspond to
NodeIndex and EdgeIndex `get` methods (note that the inner index is
already `pub` in the struct definitions). (I decided that `get()`,
used internally, just looks too generic and that client code is
clearer with more explicit method names.)
Add `EntryPat` and `NodePat` variants to ast_map, so that lookups for
id 1 in `let S{val: _x /* pat 2 */} /* pat 1 */ = ...` will actually
resolve to the pattern `S{ ... }`, rather than "unknown node", in a
function like `node_id_to_str`.
The core library in theory has 0 dependencies, but in practice it has some in
order for it to be efficient. These dependencies are in the form of the basic
memory operations provided by libc traditionally, such as memset, memcmp, etc.
These functions are trivial to implement and themselves have 0 dependencies.
This commit adds a new crate, librlibc, which will serve the purpose of
providing these dependencies. The crate is never linked to by default, but is
available to be linked to by downstream consumers. Normally these functions are
provided by the system libc, but in other freestanding contexts a libc may not
be available. In these cases, librlibc will suffice for enabling execution with
libcore.
cc #10116
pthread_yield is non-standard, while sched_yield is POSIX
The Linux documentation recommends using the standard function. This is
the only feature we're currently using that's present in glibc but not
in musl.
Previously, the `from_bits` function in the `std::bitflags::bitflags`
macro was marked as unsafe, as it did not check that the bits being
converted actually corresponded to flags.
This patch changes the function to check against the full set of
possible flags and return an `Option` which is `None` if a non-flag bit
is set. It also adds a `from_bits_truncate` function which simply zeros
any bits not corresponding to a flag.
This addresses the concern raised in https://github.com/mozilla/rust/pull/13897
After discussion with Alex, we think the proper policy is for dtors
to not fail. This is consistent with C++. BufferedWriter already
does this, so this patch modifies TempDir to not fail in the dtor,
adding a `close` method for handling errors on destruction.
The current suite of benchmarks for the standard distribution take a significant
amount of time to run, but it's unclear whether we're gaining any benefit from
running them. Some specific pain points:
* No one is looking at the data generated by the benchmarks. We have no graphs
or analysis of what's happening, so all the data is largely being cast into
the void.
* No benchmark has ever uncovered a bug, they have always run successfully.
* Benchmarks not only take a significant amount of time to run, but also take a
significant amount of time to compile. I don't think we should mitigate this
for now because it's useful to ensure that they do indeed still compile.
This commit disables --bench test runs by default as part of `make check`,
flipping the NO_BENCH environment variable to a PLEASE_BENCH variable which will
manually enable benchmarking. If and when a dedicated bot is set up for
benchmarking, this flag can be enabled on that bot.
This pull request fixes#12881.
Two caveats:
1. As explained in the commit message, this doesn't include a regression test. If this is unacceptable, please let me know, I'll see what I can do.
1. I'm getting some test failures on make check, all from debuginfo. I suspect this is due to #13680 and not related to my changes (I have GDB 7.7). This is the list of failed tests:
> [debuginfo-gdb] debuginfo/basic-types-globals.rs
> [debuginfo-gdb] debuginfo/basic-types-mut-globals.rs
> [debuginfo-gdb] debuginfo/basic-types.rs
> [debuginfo-gdb] debuginfo/borrowed-basic.rs
> [debuginfo-gdb] debuginfo/borrowed-managed-basic.rs
> [debuginfo-gdb] debuginfo/borrowed-struct.rs
> [debuginfo-gdb] debuginfo/borrowed-unique-basic.rs
> [debuginfo-gdb] debuginfo/box.rs
> [debuginfo-gdb] debuginfo/by-value-non-immediate-argument.rs
> [debuginfo-gdb] debuginfo/by-value-self-argument-in-trait-impl.rs
> [debuginfo-gdb] debuginfo/closure-in-generic-function.rs
> [debuginfo-gdb] debuginfo/evec-in-struct.rs
> [debuginfo-gdb] debuginfo/function-arg-initialization.rs
> [debuginfo-gdb] debuginfo/function-prologue-stepping-no-split-stack.rs
> [debuginfo-gdb] debuginfo/generic-function.rs
> [debuginfo-gdb] debuginfo/generic-functions-nested.rs
> [debuginfo-gdb] debuginfo/generic-method-on-generic-struct.rs
> [debuginfo-gdb] debuginfo/generic-static-method-on-struct-and-enum.rs
> [debuginfo-gdb] debuginfo/generic-struct.rs
> [debuginfo-gdb] debuginfo/lexical-scope-in-stack-closure.rs
> [debuginfo-gdb] debuginfo/lexical-scope-in-unique-closure.rs
> [debuginfo-gdb] debuginfo/method-on-generic-struct.rs
> [debuginfo-gdb] debuginfo/method-on-tuple-struct.rs
> [debuginfo-gdb] debuginfo/name-shadowing-and-scope-nesting.rs
> [debuginfo-gdb] debuginfo/recursive-struct.rs
> [debuginfo-gdb] debuginfo/self-in-generic-default-method.rs
> [debuginfo-gdb] debuginfo/shadowed-argument.rs
> [debuginfo-gdb] debuginfo/shadowed-variable.rs
> [debuginfo-gdb] debuginfo/simd.rs
> [debuginfo-gdb] debuginfo/simple-lexical-scope.rs
> [debuginfo-gdb] debuginfo/simple-struct.rs
> [debuginfo-gdb] debuginfo/simple-tuple.rs
> [debuginfo-gdb] debuginfo/static-method-on-struct-and-enum.rs
> [debuginfo-gdb] debuginfo/tuple-struct.rs
> [debuginfo-gdb] debuginfo/var-captured-in-nested-closure.rs
> [debuginfo-gdb] debuginfo/var-captured-in-sendable-closure.rs
> [debuginfo-gdb] debuginfo/var-captured-in-stack-closure.rs
I can provide the full output on request.
This allows writing a regex to filter tests more precisely, rather than having to list long paths e.g.
```
$ ./stdtest-x86_64-unknown-linux-gnu 'vec.*clone'
running 2 tests
test vec::tests::test_clone ... ok
test vec::tests::test_clone_from ... ok
test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured
```
The regex change is fully backwards compatible, since test names are Rust
identifiers + `:`, and hence not special regex characters.
(See commits for details.)
## Process API
The existing APIs for spawning processes took strings for the command
and arguments, but the underlying system may not impose utf8 encoding,
so this is overly limiting.
The assumption we actually want to make is just that the command and
arguments are viewable as [u8] slices with no interior NULLs, i.e., as
CStrings. The ToCStr trait is a handy bound for types that meet this
requirement (such as &str and Path).
However, since the commands and arguments are often a mixture of
strings and paths, it would be inconvenient to take a slice with a
single T: ToCStr bound. So this patch revamps the process creation API
to instead use a builder-style interface, called `Command`, allowing
arguments to be added one at a time with differing ToCStr
implementations for each.
The initial cut of the builder API has some drawbacks that can be
addressed once issue #13851 (libstd as a facade) is closed. These are
detailed as FIXMEs.
## Dynamic library API
`std::unstable::dynamic_library::open_external` currently takes a
`Path`, but because `Paths` produce normalized strings, this can
change the semantics of lookups in a given environment. This patch
generalizes the function to take a `ToCStr`-bounded type, which
includes both `Path`s and `str`s.
## ToCStr API
Adds ToCStr impl for &Path and ~str. This is a stopgap until DST (#12938) lands.
Until DST lands, we cannot decompose &str into & and str, so we cannot
usefully take ToCStr arguments by reference (without forcing an
additional & around &str). So we are instead temporarily adding an
instance for &Path and ~str, so that we can take ToCStr as owned. When
DST lands, the &Path instance should be removed, the string instances
should be revisted, and arguments bound by ToCStr should be passed by
reference.
FIXMEs have been added accordingly.
## Tickets closed
Closes#11650.
Closes#7928.
This adds the flag --color, which allows the user to force coloring or
turn it off. The default behavior stays the same as before (colorize, if
output goes to tty).
Why this is beneficial is explained in issue #12881.
Please note that this commit doesn't include any regression tests. I
thought about how I'd write a test for this and it doesn't seem to be
worth the effort to me for a UI change like this.
Fixes#12881.
Previously the longer hand-written usage string was never being printed:
theoretically it was trying to detect when precisely `--help` was
passed (but not `-h`), but the getopts framework was considering a check
for the presence of `-h` to be a check for that of `--help` too,
i.e. the code was always going through the `-h` path.
This changes it to print the extended usage for both `-h` and `--help`,
meaning that it does actually appear correctly.
Submitting PR again, because I cannot reopen#13349, and github does not attach new patch to that PR.
=======
Optimize `Once::doit`: perform optimistic check that initializtion is
already completed. `load` is much cheaper than `fetch_add` at least
on x86_64.
Verified with this test:
```
static mut o: one::Once = one::ONCE_INIT;
unsafe {
loop {
let start = time::precise_time_ns();
let iters = 50000000u64;
for _ in range(0, iters) {
o.doit(|| { println!("once!"); });
}
let end = time::precise_time_ns();
let ps_per_iter = 1000 * (end - start) / iters;
println!("{} ps per iter", ps_per_iter);
// confuse the optimizer
o.doit(|| { println!("once!"); });
}
}
```
Test executed on Mac, Intel Core i7 2GHz. Result is:
* 20ns per iteration without patch
* 4ns per iteration with this patch applied
Once.doit could be even faster (800ps per iteration), if `doit` function
was split into a pair of `doit`/`doit_slow`, and `doit` marked as
`#[inline]` like this:
```
#[inline(always)]
pub fn doit(&self, f: ||) {
if self.cnt.load(atomics::SeqCst) < 0 {
return
}
self.doit_slow(f);
}
fn doit_slow(&self, f: ||) { ... }
```
Teach SVH computation to ignore more implementation artifacts.
In particular, this version of strict version hash (SVH) works much
like the deriving(Hash)-based implementation did, except that it
deliberately:
1. skips over content known not affect the generated crates, and,
2. uses a content-based hash for names instead of using the value of
the `Name` index itself, which can differ depending on the order
in which strings are interned (which in turn is affected by
e.g. the presence of `--cfg` options on the command line).
Fix#14132.
(Only after adding the tests did I realize that this is not really a
special case at the AST level; as far as the visitor is concerned,
`int` and `i32` and `i64` are just idents.)
Namely: non-pub `use` declarations *are* significant to the SVH
computation, since they can change which traits are part of the method
resolution step, and thus affect which methods get called from the
(potentially inlined) code.
In particular, this version of strict version hash (SVH) works much
like the deriving(Hash)-based implementation did, except that uses a
content-based hash that filters rustc implementation artifacts and
surface syntax artifacts.
Fix#14132.
