Rustdoc takes the first paragraph as a summary, so having a huge
paragraph that ends with introducing an example looked somewhat wrong on
the module page.
Originally, this was my 30 minute introduction, and we eventually made
it the opener to the book. But as #25918 has shown, the example I use
here has some issues. The good news is that Rust makes heap allocation
syntatically expensive, but the bad news is that that means showing
equivalent programs from Rust and other languages is difficult. After
thinking about it, I'm not sure this section is pulling its weight, and
since it has problems, I'd rather just pull it than try to re-write it
right now. I think the book is fine without it.
FIxes#25918
Rustdoc takes the first paragraph as a summary, so having a huge
paragraph that ends with introducing an example looked somewhat wrong on
the module page.
Reword "Writing the logic" paragraph to prevent `unwrap` being confused for a macro (and other small changes to improve the flow of the paragraph).
cc @steveklabnik
I did some preliminary editing work with No Starch on the first chapter of the book, and here's some of the results. We're going to want to return to this later when @brson etc's new rustup work is done, so this is mostly just a first pass.
But, we agreed that having separate chapters for each of this bit of intro is a bit excessive. So let's move all of this intro stuff into one chapter.
I'd appreciate a careful review of this, as there was also some confusion about some things, which resulted in me taking one huge markdown file apart and splitting it back up, as well as some editor issues, so I _think_ this looks good, but double checking things matters!
/cc @aturon
If you try to put something that's bigger than a char into a char
literal, you get an error:
fn main() {
let c = 'ஶ்ரீ';
}
error: unterminated character constant:
This is a very compiler-centric message. Yes, it's technically
'unterminated', but that's not what you, the user did wrong.
Instead, this commit changes it to
error: character literal that's larger than a char:
As this actually tells you what went wrong.
Fixes#28851
If you try to put something that's bigger than a char into a char
literal, you get an error:
fn main() {
let c = 'ஶ்ரீ';
}
error: unterminated character constant:
This is a very compiler-centric message. Yes, it's technically
'unterminated', but that's not what you, the user did wrong.
Instead, this commit changes it to
error: character literal may only contain one codepoint
As this actually tells you what went wrong.
Fixes#28851
The "m" memory constraint in inline assembly is broken (generates incorrect code or triggers LLVM asserts) and should not be used. Instead, indirect memory operands should be used with "\*m", "=\*m" and "+\*m".
Clang does this transparently by transforming "m" constraints into "\*m" indirect constraints, but for now just being able to use "\*m" directly is enough since asm! isn't stable.
While "\*m" works fine as an input operand, "=\*m" and "+\*m" need to be specified as input operands because they take a pointer value as an input. This PR relaxes the constraint checker to allow constraints starting with "=" or "+" if the constraint string contains a "\*", which indicates an indirect operand.
This (indirectly) fixes these issues: #29382, #16383 and #13366. The code will need to be changed to use "\*m" instead of "m".
Function arguments that are small aggregates get passed as integer types
instead. To correctly handle that, we need to use store_ty instead of
plain Store.
Sometimes when writing generic code you want to abstract over
owning/pointer type so that calling code isn't restricted by one
concrete owning/pointer type. This commit makes possible such code:
```
fn i_will_work_with_arc<T: Into<Arc<MyTy>>>(t: T) {
let the_arc = t.into();
// Do something
}
i_will_work_with_arc(MyTy::new());
i_will_work_with_arc(Box::new(MyTy::new()));
let arc_that_i_already_have = Arc::new(MyTy::new());
i_will_work_with_arc(arc_that_i_already_have);
```
Please note that this patch doesn't work with DSTs.
