charon_driver/translate/
translate_ctx.rs

1//! The translation contexts.
2use super::translate_crate::RustcItem;
3pub use super::translate_crate::{TraitImplSource, TransItemSource, TransItemSourceKind};
4use super::translate_generics::{BindingLevel, LifetimeMutabilityComputer};
5use charon_lib::ast::*;
6use charon_lib::formatter::{FmtCtx, IntoFormatter};
7use charon_lib::options::TranslateOptions;
8use hax::SInto;
9use rustc_middle::ty::TyCtxt;
10use std::borrow::Cow;
11use std::cell::RefCell;
12use std::collections::{HashMap, HashSet, VecDeque};
13use std::fmt::Debug;
14use std::ops::{Deref, DerefMut};
15use std::path::PathBuf;
16use std::sync::Arc;
17use std::{fmt, mem};
18
19// Re-export to avoid having to fix imports.
20pub(crate) use charon_lib::errors::{
21    DepSource, ErrorCtx, Level, error_assert, raise_error, register_error,
22};
23
24/// Translation context used while translating the crate data into our representation.
25pub struct TranslateCtx<'tcx> {
26    /// The Rust compiler type context
27    pub tcx: TyCtxt<'tcx>,
28    /// Path to the toolchain root.
29    pub sysroot: PathBuf,
30    /// The Hax context
31    pub hax_state: hax::StateWithBase<'tcx>,
32
33    /// The options that control translation.
34    pub options: TranslateOptions,
35    /// The translated data.
36    pub translated: TranslatedCrate,
37
38    /// Record data for each method whether it is ever used (called or implemented) and the
39    /// `FunDeclId`s of the implementations. We use this to lazily translate methods, so that we
40    /// skip unused default methods of large traits like `Iterator`.
41    ///
42    /// The complete scheme works as follows: by default we enqueue no methods for translation.
43    /// When we find a use of a method, we mark it "used" using `mark_method_as_used`. This
44    /// enqueues all known and future impls of this method. We also mark a method as used if we
45    /// find an implementation of it in a non-opaque impl, and if the method is a required method.
46    pub method_status: IndexMap<TraitDeclId, HashMap<TraitItemName, MethodStatus>>,
47
48    /// The map from rustc id to translated id.
49    pub id_map: HashMap<TransItemSource, ItemId>,
50    /// The reverse map of ids.
51    pub reverse_id_map: HashMap<ItemId, TransItemSource>,
52    /// The reverse filename map.
53    pub file_to_id: HashMap<FileName, FileId>,
54
55    /// Context for tracking and reporting errors.
56    pub errors: RefCell<ErrorCtx>,
57    /// The declarations we came accross and which we haven't translated yet.
58    pub items_to_translate: VecDeque<TransItemSource>,
59    /// The declaration we've already processed (successfully or not).
60    pub processed: HashSet<TransItemSource>,
61    /// Stack of the translations currently happening. Used to avoid accidental cycles.
62    pub translate_stack: Vec<ItemId>,
63    /// Cache the names to compute them only once each.
64    pub cached_names: HashMap<RustcItem, Name>,
65    /// Cache the `ItemMeta`s to compute them only once each.
66    pub cached_item_metas: HashMap<TransItemSource, ItemMeta>,
67    /// Compute which lifetimes are used in a `&'a mut T`. This is a global fixpoint analysis.
68    pub lt_mutability_computer: LifetimeMutabilityComputer,
69    /// Cache translated dyn trait preshims by generic and associated arguments.
70    /// This is used to fetch the unique preshim
71    /// when invoking dyn trait methods (see transform_dyn_trait_calls.rs).
72    pub translated_preshims: HashSet<(TraitDeclId, Vec<Ty>)>,
73}
74
75/// Tracks whether a method is used (i.e. called or (non-opaquely) implemented).
76#[derive(Debug)]
77pub enum MethodStatus {
78    Unused {
79        /// The `FunDeclId`s of the method implementations. Because the method is unused, these
80        /// items are not enqueued for translation yet. When marking the method as used we'll
81        /// enqueue them.
82        implementors: HashSet<FunDeclId>,
83    },
84    Used,
85}
86
87impl Default for MethodStatus {
88    fn default() -> Self {
89        Self::Unused {
90            implementors: Default::default(),
91        }
92    }
93}
94
95/// A translation context for items.
96/// Augments the [TranslateCtx] with type-level variables.
97pub(crate) struct ItemTransCtx<'tcx, 'ctx> {
98    /// The definition we are currently extracting.
99    pub item_src: TransItemSource,
100    /// The id of the definition we are currently extracting, if there is one.
101    pub item_id: Option<ItemId>,
102    /// The translation context containing the top-level definitions/ids.
103    pub t_ctx: &'ctx mut TranslateCtx<'tcx>,
104    /// The Hax context with the current `DefId`.
105    pub hax_state: hax::StateWithOwner<'tcx>,
106    /// Whether to consider a `ImplExprAtom::Error` as an error for us. True except inside type
107    /// aliases, because rust does not enforce correct trait bounds on type aliases.
108    pub error_on_impl_expr_error: bool,
109
110    /// The stack of generic parameter binders for the current context. Each binder introduces an
111    /// entry in this stack, with the entry as index `0` being the innermost binder. These
112    /// parameters are referenced using [`DeBruijnVar`]; see there for details.
113    pub binding_levels: BindingStack<BindingLevel>,
114    /// When `Some`, translate any erased lifetime to a fresh `Region::Body` lifetime.
115    pub lifetime_freshener: Option<IndexMap<RegionId, ()>>,
116}
117
118/// Translates `T` into `U` using `hax`'s `SInto` trait, catching any hax panics.
119pub fn catch_sinto<S, T, U>(
120    s: &S,
121    err: &mut ErrorCtx,
122    krate: &TranslatedCrate,
123    span: Span,
124    x: &T,
125) -> Result<U, Error>
126where
127    T: Debug + SInto<S, U>,
128{
129    let unwind_safe_s = std::panic::AssertUnwindSafe(s);
130    let unwind_safe_x = std::panic::AssertUnwindSafe(x);
131    std::panic::catch_unwind(move || unwind_safe_x.sinto(*unwind_safe_s)).or_else(|_| {
132        raise_error!(
133            err,
134            crate(krate),
135            span,
136            "Hax panicked when translating `{x:?}`."
137        )
138    })
139}
140
141impl<'tcx, 'ctx> TranslateCtx<'tcx> {
142    /// Span an error and register the error.
143    pub fn span_err(&self, span: Span, msg: &str, level: Level) -> Error {
144        self.errors
145            .borrow_mut()
146            .span_err(&self.translated, span, msg, level)
147    }
148
149    /// Translates `T` into `U` using `hax`'s `SInto` trait, catching any hax panics.
150    pub fn catch_sinto<S, T, U>(&mut self, s: &S, span: Span, x: &T) -> Result<U, Error>
151    where
152        T: Debug + SInto<S, U>,
153    {
154        catch_sinto(s, &mut *self.errors.borrow_mut(), &self.translated, span, x)
155    }
156
157    /// Return the polymorphic definition for this item. Use with care, prefer `hax_def` whenever
158    /// possible.
159    ///
160    /// Used for computing names, for associated items, and for various checks.
161    pub fn poly_hax_def(&mut self, def_id: &hax::DefId) -> Result<Arc<hax::FullDef>, Error> {
162        self.hax_def_for_item(&RustcItem::Poly(def_id.clone()))
163    }
164
165    /// Return the definition for this item. This uses the polymorphic or monomorphic definition
166    /// depending on user choice.
167    pub fn hax_def_for_item(&mut self, item: &RustcItem) -> Result<Arc<hax::FullDef>, Error> {
168        let def_id = item.def_id();
169        let span = self.def_span(def_id);
170        if let RustcItem::Mono(item_ref) = item
171            && item_ref.has_non_lt_param
172        {
173            raise_error!(self, span, "Item is not monomorphic: {item:?}")
174        }
175        // Hax takes care of caching the translation.
176        let unwind_safe_s = std::panic::AssertUnwindSafe(&self.hax_state);
177        std::panic::catch_unwind(move || match item {
178            RustcItem::Poly(def_id) => def_id.full_def(*unwind_safe_s),
179            RustcItem::Mono(item_ref) => item_ref.instantiated_full_def(*unwind_safe_s),
180            RustcItem::MonoTrait(def_id) => def_id.full_def(*unwind_safe_s),
181        })
182        .or_else(|_| raise_error!(self, span, "Hax panicked when translating `{def_id:?}`."))
183    }
184
185    pub(crate) fn with_def_id<F, T>(
186        &mut self,
187        def_id: &hax::DefId,
188        item_id: Option<ItemId>,
189        f: F,
190    ) -> T
191    where
192        F: FnOnce(&mut Self) -> T,
193    {
194        let mut errors = self.errors.borrow_mut();
195        let current_def_id = mem::replace(&mut errors.def_id, item_id);
196        let current_def_id_is_local = mem::replace(&mut errors.def_id_is_local, def_id.is_local());
197        drop(errors); // important: release the refcell "lock"
198        let ret = f(self);
199        let mut errors = self.errors.borrow_mut();
200        errors.def_id = current_def_id;
201        errors.def_id_is_local = current_def_id_is_local;
202        ret
203    }
204}
205
206impl<'tcx, 'ctx> ItemTransCtx<'tcx, 'ctx> {
207    /// Create a new `ExecContext`.
208    pub(crate) fn new(
209        item_src: TransItemSource,
210        item_id: Option<ItemId>,
211        t_ctx: &'ctx mut TranslateCtx<'tcx>,
212    ) -> Self {
213        use hax::BaseState;
214        let hax_state_with_id = t_ctx.hax_state.clone().with_hax_owner(&item_src.def_id());
215        ItemTransCtx {
216            item_src,
217            item_id,
218            t_ctx,
219            hax_state: hax_state_with_id,
220            error_on_impl_expr_error: true,
221            binding_levels: Default::default(),
222            lifetime_freshener: None,
223        }
224    }
225
226    /// Whether to monomorphize items we encounter.
227    pub fn monomorphize(&self) -> bool {
228        matches!(
229            self.item_src.item,
230            RustcItem::Mono(..) | RustcItem::MonoTrait(..)
231        )
232    }
233
234    pub fn span_err(&self, span: Span, msg: &str, level: Level) -> Error {
235        self.t_ctx.span_err(span, msg, level)
236    }
237
238    pub fn hax_state(&self) -> &hax::StateWithBase<'tcx> {
239        &self.t_ctx.hax_state
240    }
241
242    pub fn hax_state_with_id(&self) -> &hax::StateWithOwner<'tcx> {
243        &self.hax_state
244    }
245
246    pub fn catch_sinto<T, U>(&mut self, span: Span, x: &T) -> Result<U, Error>
247    where
248        T: Debug + SInto<hax::StateWithOwner<'tcx>, U>,
249    {
250        self.t_ctx.catch_sinto(&self.hax_state, span, x)
251    }
252
253    /// Return the definition for this item. This uses the polymorphic or monomorphic definition
254    /// depending on user choice. For `TraitDecl` or `VTable`, we always use polymorphic definitions.
255    pub fn hax_def(&mut self, item: &hax::ItemRef) -> Result<Arc<hax::FullDef>, Error> {
256        let item = if self.monomorphize()
257            && !matches!(
258                self.item_src.kind,
259                TransItemSourceKind::TraitDecl | TransItemSourceKind::VTable
260            ) {
261            RustcItem::Mono(item.clone())
262        } else {
263            RustcItem::Poly(item.def_id.clone())
264        };
265        self.t_ctx.hax_def_for_item(&item)
266    }
267
268    pub(crate) fn poly_hax_def(&mut self, def_id: &hax::DefId) -> Result<Arc<hax::FullDef>, Error> {
269        self.t_ctx.poly_hax_def(def_id)
270    }
271}
272
273impl<'tcx> Deref for ItemTransCtx<'tcx, '_> {
274    type Target = TranslateCtx<'tcx>;
275    fn deref(&self) -> &Self::Target {
276        self.t_ctx
277    }
278}
279impl<'tcx> DerefMut for ItemTransCtx<'tcx, '_> {
280    fn deref_mut(&mut self) -> &mut Self::Target {
281        self.t_ctx
282    }
283}
284
285impl<'a> IntoFormatter for &'a TranslateCtx<'_> {
286    type C = FmtCtx<'a>;
287    fn into_fmt(self) -> Self::C {
288        self.translated.into_fmt()
289    }
290}
291
292impl<'a> IntoFormatter for &'a ItemTransCtx<'_, '_> {
293    type C = FmtCtx<'a>;
294    fn into_fmt(self) -> Self::C {
295        FmtCtx {
296            translated: Some(&self.t_ctx.translated),
297            generics: self.binding_levels.map_ref(|bl| Cow::Borrowed(&bl.params)),
298            locals: None,
299            indent_level: 0,
300        }
301    }
302}
303
304impl<'tcx, 'ctx> fmt::Display for TranslateCtx<'tcx> {
305    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
306        self.translated.fmt(f)
307    }
308}
charon_driver/translate/translate_ctx.rs

charon_driver/translate/
translate_ctx.rs
