rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Rollup merge of #143084 - RalfJung:const-eval-recursive-static-write, r=oli-obk

Browse Source 
const-eval: error when initializing a static writes to that static

Fixes https://github.com/rust-lang/rust/issues/142404 by also calling the relevant hook for writes, not just reads. To avoid erroring during the actual write of the initial value, we neuter the hook when popping the final stack frame.

Calling the hook during writes requires changing its signature since we cannot pass in the entire interpreter any more.

While doing this I also realized a gap in https://github.com/rust-lang/rust/pull/142575 for zero-sized copies on the read side, so I fixed that and added a test.

r? `@oli-obk`
This commit is contained in:
Guillaume Gomez
2025-06-27 15:04:57 +02:00
committed by GitHub
parent 8e7b0b57ea ed4f01ed2e
commit 0bbeeffe57
15 changed files with 133 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
compiler/rustc_const_eval/src/const_eval/machine.rs
View File

@@ -62,7 +62,7 @@ pub struct CompileTimeMachine<'tcx> {
/// If `Some`, we are evaluating the initializer of the static with the given `LocalDefId`,
/// storing the result in the given `AllocId`.
/// Used to prevent reads from a static's base allocation, as that may allow for self-initialization loops.
/// Used to prevent accesses to a static's base allocation, as that may allow for self-initialization loops.
pub(crate) static_root_ids: Option<(AllocId, LocalDefId)>,
/// A cache of "data range" computations for unions (i.e., the offsets of non-padding bytes).
@@ -705,19 +705,27 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
interp_ok(())
}
fn before_alloc_read(ecx: &InterpCx<'tcx, Self>, alloc_id: AllocId) -> InterpResult<'tcx> {
fn before_alloc_access(
tcx: TyCtxtAt<'tcx>,
machine: &Self,
alloc_id: AllocId,
) -> InterpResult<'tcx> {
if machine.stack.is_empty() {
// Get out of the way for the final copy.
return interp_ok(());
}
// Check if this is the currently evaluated static.
if Some(alloc_id) == ecx.machine.static_root_ids.map(|(id, _)| id) {
if Some(alloc_id) == machine.static_root_ids.map(|(id, _)| id) {
return Err(ConstEvalErrKind::RecursiveStatic).into();
}
// If this is another static, make sure we fire off the query to detect cycles.
// But only do that when checks for static recursion are enabled.
if ecx.machine.static_root_ids.is_some() {
if let Some(GlobalAlloc::Static(def_id)) = ecx.tcx.try_get_global_alloc(alloc_id) {
if ecx.tcx.is_foreign_item(def_id) {
if machine.static_root_ids.is_some() {
if let Some(GlobalAlloc::Static(def_id)) = tcx.try_get_global_alloc(alloc_id) {
if tcx.is_foreign_item(def_id) {
throw_unsup!(ExternStatic(def_id));
}
ecx.ctfe_query(|tcx| tcx.eval_static_initializer(def_id))?;
tcx.eval_static_initializer(def_id)?;
}
}
interp_ok(())