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Auto merge of #113695 - bjorn3:fix_rlib_cdylib_metadata_handling, r=pnkfelix,petrochenkov

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Verify that all crate sources are in sync

This ensures that rustc will not attempt to link against a cdylib as if it is a rust dylib when an rlib for the same crate is available. Previously rustc didn't actually check if any further formats of a crate which has been loaded are of the same version and if they are actually valid. This caused a cdylib to be interpreted as rust dylib as soon as the corresponding rlib was loaded. As cdylibs don't export any rust symbols, linking would fail if rustc decides to link against the cdylib rather than the rlib.

Two crates depended on the previous behavior by separately compiling a test crate as both rlib and dylib. These have been changed to capture their original spirit to the best of my ability while still working when rustc verifies that all crates are in sync. It is unlikely that build systems depend on the current behavior and in any case we are taking a lot of measures to ensure that any change to either the source or the compilation options (including crate type) results in rustc rejecting it as incompatible. We merely didn't do this check here for now obsolete perf reasons.

Fixes https://github.com/rust-lang/rust/issues/10786
Fixes https://github.com/rust-lang/rust/issues/82151
Fixes https://github.com/rust-lang/rust/issues/82972
Closes https://github.com/bevy-cheatbook/bevy-cheatbook/issues/114
This commit is contained in:
bors 2023-07-20 09:00:10 +00:00
commit b14fd2359f
17 changed files with 100 additions and 79 deletions
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20
compiler/rustc_codegen_ssa/src/back/metadata.rs
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@ -10,8 +10,6 @@ use object::{
ObjectSymbol, SectionFlags, SectionKind, SymbolFlags, SymbolKind, SymbolScope,
};
use snap::write::FrameEncoder;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::owned_slice::{try_slice_owned, OwnedSlice};
use rustc_metadata::fs::METADATA_FILENAME;
@ -481,19 +479,15 @@ pub fn create_compressed_metadata_file(
metadata: &EncodedMetadata,
symbol_name: &str,
) -> Vec<u8> {
let mut compressed = rustc_metadata::METADATA_HEADER.to_vec();
// Our length will be backfilled once we're done writing
compressed.write_all(&[0; 4]).unwrap();
FrameEncoder::new(&mut compressed).write_all(metadata.raw_data()).unwrap();
let meta_len = rustc_metadata::METADATA_HEADER.len();
let data_len = (compressed.len() - meta_len - 4) as u32;
compressed[meta_len..meta_len + 4].copy_from_slice(&data_len.to_be_bytes());
let mut packed_metadata = rustc_metadata::METADATA_HEADER.to_vec();
packed_metadata.write_all(&(metadata.raw_data().len() as u32).to_be_bytes()).unwrap();
packed_metadata.extend(metadata.raw_data());
let Some(mut file) = create_object_file(sess) else {
return compressed.to_vec();
return packed_metadata.to_vec();
};
if file.format() == BinaryFormat::Xcoff {
return create_compressed_metadata_file_for_xcoff(file, &compressed, symbol_name);
return create_compressed_metadata_file_for_xcoff(file, &packed_metadata, symbol_name);
}
let section = file.add_section(
file.segment_name(StandardSegment::Data).to_vec(),
@ -507,14 +501,14 @@ pub fn create_compressed_metadata_file(
}
_ => {}
};
let offset = file.append_section_data(section, &compressed, 1);
let offset = file.append_section_data(section, &packed_metadata, 1);
// For MachO and probably PE this is necessary to prevent the linker from throwing away the
// .rustc section. For ELF this isn't necessary, but it also doesn't harm.
file.add_symbol(Symbol {
name: symbol_name.as_bytes().to_vec(),
value: offset,
size: compressed.len() as u64,
size: packed_metadata.len() as u64,
kind: SymbolKind::Data,
scope: SymbolScope::Dynamic,
weak: false,