Various FIXME comments added around to denote copies which when removed cause
the compiler to segfault at some point before stage2. None of these copies
should even be necessary.
The typechecker previously passed around a boolean return flag to
indicate whether it saw something with type _|_ (that is, something
it knows at compile-time will definitely diverge) and also had some
manual checks for the `ty_err` pseudo-type that represents a previous
type error. This was because the typing rules implemented by the
typechecker didn't properly propagate _|_ and ty_err. I fixed it.
This also required changing expected error messages in a few tests,
as now we're printing out fewer derived errors -- in fact, at this
point we should print out no derived errors, so report any that
you see (ones that include "[type error]") as bugs.
Removes a lot of instances of `/*bad*/ copy` throughout libsyntax/librustc. On the plus side, this shaves about 2s off of the runtime when compiling `librustc` with optimizations.
Ideally I would have run a profiler to figure out which copies are the most critical to remove, but in reality there was a liberal amount of `git grep`s along with some spot checking and removing the easy ones.
For bootstrapping purposes, this commit does not remove all uses of
the keyword "pure" -- doing so would cause the compiler to no longer
bootstrap due to some syntax extensions ("deriving" in particular).
Instead, it makes the compiler ignore "pure". Post-snapshot, we can
remove "pure" from the language.
There are quite a few (~100) borrow check errors that were essentially
all the result of mutable fields or partial borrows of `@mut`. Per
discussions with Niko I think we want to allow partial borrows of
`@mut` but detect obvious footguns. We should also improve the error
message when `@mut` is erroneously reborrowed.
Before:
````
test.rs:3:21: 3:30 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^~~~~~~~~
````
After:
````
test.rs:3:27: 3:28 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^
````
Before:
````
test.rs:3:21: 3:30 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^~~~~~~~~
````
After:
````
test.rs:3:27: 3:28 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^
````
The basic idea is that we add a new kind of adjustment, AutoAddEnv, that pads
an extern fn into a closure by adding the extra NULL word. Then there are a few
misc changes in trans to get the LLVM types to match up.
Fixes#4808.
