This commit does the following.
- Removes parsing support for '\X12', '\u123456' and '\U12345678' char
literals. These are no longer valid Rust and rejected by the lexer.
(This strange-sounding situation occurs because the parser rescans
char literals to compute their value.)
- Rearranges the function so that all the escaped values are handled in
a single `match`, and changes the error-handling to use vanilla
assert!() and unwrap().
This reduces the time taken to run
`rustc -Zparse-only rustc-benchmarks/issue-32278-big-array-of-strings`
from 0.18s to 0.15s on my machine, and reduces the number of
instructions (as measured by Cachegrind) from 1.34B to 1.01B.
With the change applied, the time to fully compile that benchmark is
1.96s, so this is a 1.5% improvement.
Added tokenstream parser procedure
A tiny PR that simply adds a procedure for parsing `TokenStream`s to the parser in `src/libsyntax`. This is to ease using `TokenStream`s with the current (old) procedural macro system.
To allow these braced macro invocation, this PR removes the optional expression from `ast::Block` and instead uses a `StmtKind::Expr` at the end of the statement list.
Currently, braced macro invocations in blocks can expand into statements (and items) except when they are last in a block, in which case they can only expand into expressions.
For example,
```rust
macro_rules! make_stmt {
() => { let x = 0; }
}
fn f() {
make_stmt! {} //< This is OK...
let x = 0; //< ... unless this line is commented out.
}
```
Fixes#34418.
syntax-[breaking-change] cc #31645
(Only breaking because ast::TokenTree is now tokenstream::TokenTree.)
This pull request refactors TokenTrees into their own file as src/libsyntax/tokenstream.rs, moving them out of src/libsyntax/ast.rs, in order to prepare for an accompanying TokenStream implementation (per RFC 1566).
When items are inlined from extern crates, the filename in the debug info
is taken from the FileMap that's serialized in the rlib metadata.
Currently this is just FileMap.name, which is whatever path is passed to rustc.
Since libcore and libstd are built by invoking rustc with relative paths,
they wind up with relative paths in the rlib, and when linked into a binary
the debug info uses relative paths for the names, but since the compilation
directory for the final binary, tools trying to read source filenames
will wind up with bad paths. We noticed this in Firefox with source
filenames from libcore/libstd having bad paths.
This change stores an absolute path in FileMap.abs_path, and uses that
if available for writing debug info. This is not going to magically make
debuggers able to find the source, but it will at least provide sensible
paths.
The extra filename and line was mainly there to keep the indentation
relative to the main snippet; now that this doesn't include
filename/line-number as a prefix, it is distracted.
