add support for `#[global_allocator]`
This PR adds support for custom global allocators. Unfortunately, the code given in #1207 still causes errors when used with box. I believe this is because Box is special-cased in miri and stacked borrows.
Previously the command line string would have been incorrectly constructed if argv[0] contained a doublequote (`"`) or ended in a trailing backslash (`\`). This is a very rare edge case because, by convention, argv[0] is the path to the application and Windows file names cannot contain doublequotes.
Fixes#1881
add support for `#[start]`
This PR adds support for the `#[start]` attribute and fixes#1825.
It also renames `eval_main` to `eval_entry` to reflect that it can evaluate any entry function.
Add support for the `volatile_set_memory` intrinsic
Add support for the unstable `volatile_set_memory` intrinsic
(Runtime behaviour and soundness requirements for `volatile_set_memory` are identical to those of `write_bytes`, so supporting this intrinsic is trivial.)
also ignore 'thread leaks' with -Zmiri-ignore-leaks
This is a step towards https://github.com/rust-lang/miri/issues/1371. The remaining hard part would be supporting checking for memory leaks when there are threads still running. For now we elegantly avoid this problem by using the same flag to control both of these checks. :)
Change the code to either `EACCES` (if the op is performed on the
path), or `EBADF` (if the op is performed the fd)
Updated ops: `stat`, `opendir`, `ftruncate64`, and `readlink`
Add a new test for fs ops in isolation.
Update posix fs shims to use new API `reject_in_isolation`, which
allows rejection with error code instead of always forcing abort.
Error code chosen for each op is the most appropriate one from the
list in corresponding syscall's manual.
Updated helper APIs to not use quotes (`) around input name while
preparing the message. This allows callers to pass multi-word string
like -- "`read` from stdin".
Filter out items other than non-generic functions and statics in our version of `exported_symbols`
[`#[no_mangle]` on a `use` item](https://docs.rs/brotli-decompressor/2.3.1/src/brotli_decompressor/ffi/mod.rs.html#3-5) can make Miri ICE when compiling a dependency (rust-lang/rust#86261):
```rs
#[no_mangle]
use std::{thread,panic, io, boxed, any, string};
```
<details>
```
error: internal compiler error: compiler/rustc_middle/src/ty/mod.rs:1650:13: item_name: no name for DefPath { data: [DisambiguatedDefPathData { data: Misc, disambiguator: 14 }], krate: crate0 }
thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1007:9
stack backtrace:
0: std::panicking::begin_panic
1: std::panic::panic_any
2: rustc_errors::HandlerInner::bug
3: rustc_errors::Handler::bug
4: rustc_middle::ty::context::tls::with_opt
5: rustc_middle::util::bug::opt_span_bug_fmt
6: rustc_middle::util::bug::bug_fmt
7: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::item_name
8: rustc_symbol_mangling::symbol_name_provider
9: rustc_query_impl::<impl rustc_query_system::query::config::QueryAccessors<rustc_query_impl::plumbing::QueryCtxt> for rustc_query_impl::queries::symbol_name>::compute
10: rustc_query_system::query::plumbing::get_query_impl
11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::symbol_name
12: rustc_middle::middle::exported_symbols::ExportedSymbol::symbol_name_for_local_instance
13: rustc_codegen_ssa::back::symbol_export::symbol_name_for_instance_in_crate
14: rustc_codegen_ssa::back::linker::exported_symbols
15: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
16: rustc_codegen_ssa::back::linker::LinkerInfo::new
17: rustc_codegen_ssa::back::write::start_async_codegen
18: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
19: rustc_interface::passes::QueryContext::enter
20: rustc_interface::queries::Queries::ongoing_codegen
21: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
22: rustc_span::with_source_map
23: rustc_interface::interface::create_compiler_and_run
24: rustc_span::with_session_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md
note: rustc 1.54.0-nightly (a50d72158 2021-06-08) running on x86_64-unknown-linux-gnu
note: compiler flags: -C embed-bitcode=no -C debuginfo=1 --crate-type lib
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
#0 [symbol_name] computing the symbol for `{misc#14}`
end of query stack
```
</details>
This might be because in #1776, we override the `exported_symbols` query, and our version of `exported_symbols` can return a `use` item which don't have a name if the `use` item is tagged with `#[no_mangle]`, and then:
- `rustc_codegen_ssa::back::symbol_export::symbol_name_for_instance_in_crate` is called for for every `exported_symbols`: https://github.com/rust-lang/rust/blob/fb3ea63d9b4c3e9bb90d4250b870faaffb9c8fd2/compiler/rustc_codegen_ssa/src/back/linker.rs#L1300-L1304
- it calls `rustc_middle::middle::exported_symbols::ExportedSymbol::symbol_name_for_local_instance`: https://github.com/rust-lang/rust/blob/fb3ea63d9b4c3e9bb90d4250b870faaffb9c8fd2/compiler/rustc_codegen_ssa/src/back/symbol_export.rs#L412
- which calls `rustc_symbol_mangling::symbol_name_provider`: https://github.com/rust-lang/rust/blob/fb3ea63d9b4c3e9bb90d4250b870faaffb9c8fd2/compiler/rustc_middle/src/middle/exported_symbols.rs#L37-L44
- which calls `item_name`: https://github.com/rust-lang/rust/blob/fb3ea63d9b4c3e9bb90d4250b870faaffb9c8fd2/compiler/rustc_symbol_mangling/src/lib.rs#L216, which triggers the ICE
It might also be problematic for https://github.com/rust-lang/miri/blob/d39f0c64b8b369188a73a655716ab56683a6537b/src/shims/foreign_items.rs#L165 which also uses `item_name`, but Miri cannot compile the dependency, so that code can't be reached.
Therefore, this PR makes `exported_symbols` filter out all items that are not functions or statics, so all items returned will have a name, which avoids the ICE (I have tested it in the https://github.com/jorgecarleitao/arrow2 repository).
(This PR also includes a commit that fixes a small (unrelated) bug for `#[no_mangle]` on associated functions -- I found that because I notice `#[no_mangle]` is supported on associated functions and they should not be filtered out in `exported_symbols`.)
Fixes (when the submodule is bumped) rust-lang/rust#86261.
Report an error if a `#[no_mangle]`/`#[export_name = ...]` function has the same symbol name as a built-in shim
Implements https://github.com/rust-lang/miri/pull/1776#issuecomment-821322605.
The error looks like this:
```
error: found `malloc` symbol definition that clashes with a built-in shim
--> tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:12:9
|
12 | malloc(0);
| ^^^^^^^^^ found `malloc` symbol definition that clashes with a built-in shim
|
help: the `malloc` symbol is defined here
--> tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:2:1
|
2 | / extern "C" fn malloc(_: usize) -> *mut std::ffi::c_void {
3 | | //~^ HELP the `malloc` symbol is defined here
4 | | unreachable!()
5 | | }
| |_^
= note: inside `main` at tests/compile-fail/function_calls/exported_symbol_shim_clashing.rs:12:9
```
This does not implement "better error messages than we do currently for arg/ABI mismatches" in https://github.com/rust-lang/miri/pull/1776#issuecomment-821343175 -- I failed to remove all `check_arg_count()` and `check_abi()` (they are still used in `src/shims/intrinsics.rs` and `call_dlsym()`) and they don't receive the name of the shim.
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