Fix syntax error in the compiler
Currently `rustc` accepts the following code: `fn f<'a>() where 'a {}`. This should be a syntax error, shouldn't it?
Not sure if my changes actually compile, waiting for the LLVM to build.
trans: Make type names in LLVM IR independent of crate-nums and source locations.
UPDATE:
This PR makes the type names we assign in LLVM IR independent of the type definition's location in the source code and the order in which extern crates are loaded. The new type names look like the old ones, except for closures and the `<crate-num>.` prefix being gone. Resolution of name clashes (e.g. of the same type in different crate versions) is left to LLVM (which will just append `.<counter>` to the name).
ORIGINAL TEXT:
This PR makes the type names we assign in LLVM IR independent of the type definition's location in the source code. Before, the type of closures contained the closures definition location. The new naming scheme follows the same pattern that we already use for symbol names: We have a human readable prefix followed by a hash that makes sure we don't have any collisions. Here is an example of what the new names look like:
```rust
// prog.rs - example program
mod mod1
{
pub struct Struct<T>(pub T);
}
fn main() {
use mod1::Struct;
let _s = Struct(0u32);
let _t = Struct('h');
let _x = Struct(Struct(0i32));
}
```
Old:
```llvm
%"mod1::Struct<u32>" = type { i32 }
%"mod1::Struct<char>" = type { i32 }
%"mod1::Struct<mod1::Struct<i32>>" = type { %"mod1::Struct<i32>" }
%"mod1::Struct<i32>" = type { i32 }
```
New:
```llvm
%"prog::mod1::Struct<u32>::ejDrT" = type { i32 }
%"prog::mod1::Struct<char>::2eEAU" = type { i32 }
%"prog::mod1::Struct<prog::mod1::Struct<i32>>::ehCqR" = type { %"prog::mod1::Struct<i32>::$fAo2" }
%"prog::mod1::Struct<i32>::$fAo2" = type { i32 }
```
As you can see, the new names are slightly more verbose, but also more consistent. There is no difference now between a local type and one from another crate (before, non-local types where prefixed with `<crate-num>.` as in `2.std::mod1::Type1`).
There is a bit of design space here. For example, we could leave off the crate name for local definitions (making names shorter but less consistent):
```llvm
%"mod1::Struct<u32>::ejDrT" = type { i32 }
%"mod1::Struct<char>::2eEAU" = type { i32 }
%"mod1::Struct<mod1::Struct<i32>>::ehCqR" = type { %"mod1::Struct<i32>::$fAo2" }
%"mod1::Struct<i32>::$fAo2" = type { i32 }
```
We could also put the hash in front, which might be more readable:
```llvm
%"ejDrT.mod1::Struct<u32>" = type { i32 }
%"2eEAU.mod1::Struct<char>" = type { i32 }
%"ehCqR.mod1::Struct<mod1::Struct<i32>>" = type { %"$fAo2.mod1::Struct<i32>" }
%"$fAo2.mod1::Struct<i32>" = type { i32 }
```
We could probably also get rid of the hash if we used full DefPaths and crate-nums (though I'm not yet a 100% sure if crate-nums could mess with incremental compilation).
```llvm
%"mod1::Struct<u32>" = type { i32 }
%"mod1::Struct<char>" = type { i32 }
%"mod1::Struct<mod1::Struct<i32>>" = type { %"mod1::Struct<i32>" }
%"mod1::Struct<i32>" = type { i32 }
%"2.std::mod1::Type1" = type { ... }
```
I would prefer the solution with the hashes because it is nice and consistent conceptually, but visually it's admittedly a bit uglier. Maybe @rust-lang/compiler would like to bikeshed a little about this.
On a related note: Has anyone ever tried if the LTO-linker will merge equal types with different names?
(^ @brson, @alexcrichton ^)
If not, that would be a reason to make type names more consistent.
Similar to pull request #37430, this makes the message more copy-paste
friendly and aligns it with other messages like:
help: you can import it into scope: use foo::Bar;
Before this PR, type names could depend on the cratenum being used
for a given crate and also on the source location of closures.
Both are undesirable for incremental compilation where we cache
LLVM IR and don't want it to depend on formatting or in which
order crates are loaded.
Macro parser performance improvements and refactoring
This PR locally increased performance of https://github.com/rust-lang/rust/issues/37074 by ~6.6 minutes.
Follow up to https://github.com/rust-lang/rust/pull/37569, but doesn't focus explicitly on expansion performance.
History is relatively clean, but I can/will do some more polishing if this is deemed mergeable. Partially posting this now so I can get Travis to run tests for me.
r? @jseyfried
update_with_config_mk() needs to read the new llvm debuginfo config
option from config.mk. Other than that, rustbuild already supports
LLVM's RelWithDebInfo build type.
Impls with a erroneous trait ref are already ignored in the first part
of coherence, so ignore them in the second part too. This avoids
cascading coherence errors when 1 impl of a trait has an error.
Vec::from_iter's general case allocates the vector up front;
this is redundant for the TrustedLen case, and can then be avoided
to reduce the size of the code.
Translate closures through the collector
Now that old trans is gone, there is no need for the hack of translating closures when they are instantiated. We can translate them like regular items.
r? @eddyb
Since I said "no intentional functional change" in the previous commit,
I guess it was inevitable there were unintentional changes. Not
functional, but optimization-wise. This restores the extend
specialization's use in Vec::from_iter.
to let people experiment with this target out of tree.
The MSP430 architecture is used in 16-bit microcontrollers commonly used
in Digital Signal Processing applications.
compile-test: allow overriding nodejs binary location
Add a command-line argument to manually specify which nodejs binary should be used,
which disables the default search.
Original work done by @tari.
Fixes#34188.
When compiling compiler-rt you typically compile with `-fvisibility=hidden`
which to ensure that all symbols are hidden in shared objects and don't show up
in symbol tables. This is important for these intrinsics being linked in every
crate to ensure that we're not unnecessarily bloating the public ABI of Rust
crates.
This should help allow the compiler-builtins project with Rust-defined builtins
start landing in-tree as well.
