NOTE: I was careful to make each change in a manner that preserves the
existing diagnostic output (usually by ensuring that no lines were
added or removed). This means that the resulting source files are not
as nice to read as they were at the start. But we will have to review
these cases by hand anyway as follow-up work, so cleanup could
reasonably happen then (or not at all).
Better document the implementors of Clone and Copy
There are two parts to this change. The first part is a change to the compiler and to the standard library (specifically, libcore) to allow implementations of `Clone` and `Copy` to be written for a subset of builtin types. By adding these implementations to libcore, they now show up in the documentation. This is a [breaking-change] for users of `#![no_core]`, because they will now have to supply their own copy of the implementations of `Clone` and `Copy` that were added in libcore.
The second part is purely a documentation change to document the other implementors of `Clone` and `Copy` that cannot be described in Rust code (yet) and are thus provided by the compiler.
Fixes#25893
Add implementations of `Clone` and `Copy` for some primitive types to
libcore so that they show up in the documentation. The concerned types
are the following:
* All primitive signed and unsigned integer types (`usize`, `u8`, `u16`,
`u32`, `u64`, `u128`, `isize`, `i8`, `i16`, `i32`, `i64`, `i128`);
* All primitive floating point types (`f32`, `f64`)
* `bool`
* `char`
* `!`
* Raw pointers (`*const T` and `*mut T`)
* Shared references (`&'a T`)
These types already implemented `Clone` and `Copy`, but the
implementation was provided by the compiler. The compiler no longer
provides these implementations and instead tries to look them up as
normal trait implementations. The goal of this change is to make the
implementations appear in the generated documentation.
For `Copy` specifically, the compiler would reject an attempt to write
an `impl` for the primitive types listed above with error `E0206`; this
error no longer occurs for these types, but it will still occur for the
other types that used to raise that error.
The trait implementations are guarded with `#[cfg(not(stage0))]` because
they are invalid according to the stage0 compiler. When the stage0
compiler is updated to a revision that includes this change, the
attribute will have to be removed, otherwise the stage0 build will fail
because the types mentioned above no longer implement `Clone` or `Copy`.
For type variants that are variadic, such as tuples and function
pointers, and for array types, the `Clone` and `Copy` implementations
are still provided by the compiler, because the language is not
expressive enough yet to be able to write the appropriate
implementations in Rust.
The initial plan was to add `impl` blocks guarded by `#[cfg(dox)]` to
make them apply only when generating documentation, without having to
touch the compiler. However, rustdoc's usage of the compiler still
rejected those `impl` blocks.
This is a [breaking-change] for users of `#![no_core]`, because they
will now have to supply their own implementations of `Clone` and `Copy`
for the primitive types listed above. The easiest way to do that is to
simply copy the implementations from `src/libcore/clone.rs` and
`src/libcore/marker.rs`.
Fixes#25893
Add crate name to "main function not found" error message.
Fixes#44798 and rust-lang/cargo#4948.
I was wondering if it might be cleaner to update the ui tests to add a simple `fn main() {}` for the unrelated tests. Let me know if you would prefer that.
Rustc explain
Fixes#48041.
To make the review easier, I separated tests update to code update. Also, I used this script to generate new ui tests stderr:
```python
from os import listdir
from os.path import isdir, isfile, join
PATH = "src/test/ui"
def do_something(path):
files = [join(path, f) for f in listdir(path)]
for f in files:
if isdir(f):
do_something(f)
continue
if not isfile(f) or not f.endswith(".stderr"):
continue
x = open(f, "r")
content = x.read().strip()
if "error[E" not in content:
continue
errors = dict()
for y in content.splitlines():
if y.startswith("error[E"):
errors[y[6:11]] = True
errors = sorted(errors.keys())
if len(errors) < 1:
print("weird... {}".format(f))
continue
if len(errors) > 1:
content += "\n\nYou've got a few errors: {}".format(", ".join(errors))
content += "\nIf you want more information on an error, try using \"rustc --explain {}\"".format(errors[0])
else:
content += "\n\nIf you want more information on this error, try using \"rustc --explain {}\"".format(errors[0])
content += "\n"
x = open(f, "w")
x.write(content)
do_something(PATH)
```
