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Rollup merge of #66235 - eddyb:coff-syrup, r=nagisa

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rustc_metadata: don't let LLVM confuse rmeta blobs for COFF object files.

This has likely been a silent issue since 1.10 but only caused trouble recently (see https://github.com/rust-lang/rust/issues/65536#issuecomment-552018224), when recent changes to the `rmeta` schema introduced more opportunities for COFF parse errors.

To prevent any undesired interactions with old compilers, I've renamed the file inside `rlib`s from `rust.metadata.bin` to `lib.rmeta` (not strongly attached to it, suggestions welcome).

Fixes #65536.

<hr/>

Before:
```
$ llvm-objdump -all-headers build/*/stage1-std/*/release/deps/libcore-*.rmeta

build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps/libcore-6b9e8b5a59b79a1d.rmeta: file format COFF-<unknown arch>

architecture: unknown
start address: 0x00000000

Sections:
Idx Name          Size     VMA          Type

SYMBOL TABLE:
```

After:
```
$ llvm-objdump -all-headers build/*/stage1-std/*/release/deps/libcore-*.rmeta

llvm-objdump: error: 'build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps/libcore-6b9e8b5a59b79a1d.rmeta':
    The file was not recognized as a valid object file
```
This commit is contained in:
Yuki Okushi 2019-11-10 09:27:20 +09:00 • committed by GitHub
commit 0fec5ab2bb
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3 changed files with 7 additions and 9 deletions
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3
src/librustc_codegen_ssa/lib.rs
View file

@ -59,7 +59,8 @@ pub struct ModuleCodegen<M> {
pub kind: ModuleKind,
}
pub const METADATA_FILENAME: &str = "rust.metadata.bin";
// FIXME(eddyb) maybe include the crate name in this?
pub const METADATA_FILENAME: &str = "lib.rmeta";
pub const RLIB_BYTECODE_EXTENSION: &str = "bc.z";

9
src/librustc_metadata/rmeta/mod.rs
View file

@ -37,18 +37,15 @@ crate fn rustc_version() -> String {
/// Metadata encoding version.
/// N.B., increment this if you change the format of metadata such that
/// the rustc version can't be found to compare with `rustc_version()`.
const METADATA_VERSION: u8 = 4;
const METADATA_VERSION: u8 = 5;
/// Metadata header which includes `METADATA_VERSION`.
/// To get older versions of rustc to ignore this metadata,
/// there are 4 zero bytes at the start, which are treated
/// as a length of 0 by old compilers.
///
/// This header is followed by the position of the `CrateRoot`,
/// which is encoded as a 32-bit big-endian unsigned integer,
/// and further followed by the rustc version string.
crate const METADATA_HEADER: &[u8; 12] =
&[0, 0, 0, 0, b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
crate const METADATA_HEADER: &[u8; 8] =
&[b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
/// Additional metadata for a `Lazy<T>` where `T` may not be `Sized`,
/// e.g. for `Lazy<[T]>`, this is the length (count of `T` values).

4
src/test/run-make-fulldeps/invalid-library/Makefile
View file

@ -1,6 +1,6 @@
-include ../tools.mk
all:
touch $(TMPDIR)/rust.metadata.bin
$(AR) crus $(TMPDIR)/libfoo-ffffffff-1.0.rlib $(TMPDIR)/rust.metadata.bin
touch $(TMPDIR)/lib.rmeta
$(AR) crus $(TMPDIR)/libfoo-ffffffff-1.0.rlib $(TMPDIR)/lib.rmeta
$(RUSTC) foo.rs 2>&1 | $(CGREP) "can't find crate for"