Auto merge of #89266 - cjgillot:session-ich, r=michaelwoerister

Move ICH to rustc_query_system

Based on https://github.com/rust-lang/rust/pull/89183

The StableHashingContext does not need to be in rustc_middle.

This PR moves it to rustc_query_system. This will avoid a dependency between rustc_ast_lowering and rustc_middle in https://github.com/rust-lang/rust/pull/89124.

2 files changed, 202 insertions, 1 deletions

diff --git a/compiler/rustc_session/src/cstore.rs b/compiler/rustc_session/src/cstore.rs
new file mode 100644
index 00000000000..9d6bd201039
--- /dev/null
+++ b/compiler/rustc_session/src/cstore.rs
@@ -0,0 +1,199 @@
+//! the rustc crate store interface. This also includes types that
+//! are *mostly* used as a part of that interface, but these should
+//! probably get a better home if someone can find one.
+
+use crate::search_paths::PathKind;
+use crate::utils::NativeLibKind;
+use rustc_ast as ast;
+use rustc_data_structures::sync::{self, MetadataRef};
+use rustc_hir::def_id::{CrateNum, DefId, StableCrateId, LOCAL_CRATE};
+use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
+use rustc_span::hygiene::{ExpnHash, ExpnId};
+use rustc_span::symbol::Symbol;
+use rustc_span::Span;
+use rustc_target::spec::Target;
+
+use std::any::Any;
+use std::path::{Path, PathBuf};
+
+// lonely orphan structs and enums looking for a better home
+
+/// Where a crate came from on the local filesystem. One of these three options
+/// must be non-None.
+#[derive(PartialEq, Clone, Debug, HashStable_Generic, Encodable, Decodable)]
+pub struct CrateSource {
+    pub dylib: Option<(PathBuf, PathKind)>,
+    pub rlib: Option<(PathBuf, PathKind)>,
+    pub rmeta: Option<(PathBuf, PathKind)>,
+}
+
+impl CrateSource {
+    #[inline]
+    pub fn paths(&self) -> impl Iterator<Item = &PathBuf> {
+        self.dylib.iter().chain(self.rlib.iter()).chain(self.rmeta.iter()).map(|p| &p.0)
+    }
+}
+
+#[derive(Encodable, Decodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
+#[derive(HashStable_Generic)]
+pub enum CrateDepKind {
+    /// A dependency that is only used for its macros.
+    MacrosOnly,
+    /// A dependency that is always injected into the dependency list and so
+    /// doesn't need to be linked to an rlib, e.g., the injected allocator.
+    Implicit,
+    /// A dependency that is required by an rlib version of this crate.
+    /// Ordinary `extern crate`s result in `Explicit` dependencies.
+    Explicit,
+}
+
+impl CrateDepKind {
+    #[inline]
+    pub fn macros_only(self) -> bool {
+        match self {
+            CrateDepKind::MacrosOnly => true,
+            CrateDepKind::Implicit | CrateDepKind::Explicit => false,
+        }
+    }
+}
+
+#[derive(Copy, Debug, PartialEq, Clone, Encodable, Decodable, HashStable_Generic)]
+pub enum LinkagePreference {
+    RequireDynamic,
+    RequireStatic,
+}
+
+#[derive(Debug, Encodable, Decodable, HashStable_Generic)]
+pub struct NativeLib {
+    pub kind: NativeLibKind,
+    pub name: Option<Symbol>,
+    pub cfg: Option<ast::MetaItem>,
+    pub foreign_module: Option<DefId>,
+    pub wasm_import_module: Option<Symbol>,
+    pub verbatim: Option<bool>,
+    pub dll_imports: Vec<DllImport>,
+}
+
+#[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
+pub struct DllImport {
+    pub name: Symbol,
+    pub ordinal: Option<u16>,
+    /// Calling convention for the function.
+    ///
+    /// On x86_64, this is always `DllCallingConvention::C`; on i686, it can be any
+    /// of the values, and we use `DllCallingConvention::C` to represent `"cdecl"`.
+    pub calling_convention: DllCallingConvention,
+    /// Span of import's "extern" declaration; used for diagnostics.
+    pub span: Span,
+}
+
+/// Calling convention for a function defined in an external library.
+///
+/// The usize value, where present, indicates the size of the function's argument list
+/// in bytes.
+#[derive(Clone, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
+pub enum DllCallingConvention {
+    C,
+    Stdcall(usize),
+    Fastcall(usize),
+    Vectorcall(usize),
+}
+
+#[derive(Clone, Encodable, Decodable, HashStable_Generic, Debug)]
+pub struct ForeignModule {
+    pub foreign_items: Vec<DefId>,
+    pub def_id: DefId,
+}
+
+#[derive(Copy, Clone, Debug, HashStable_Generic)]
+pub struct ExternCrate {
+    pub src: ExternCrateSource,
+
+    /// span of the extern crate that caused this to be loaded
+    pub span: Span,
+
+    /// Number of links to reach the extern;
+    /// used to select the extern with the shortest path
+    pub path_len: usize,
+
+    /// Crate that depends on this crate
+    pub dependency_of: CrateNum,
+}
+
+impl ExternCrate {
+    /// If true, then this crate is the crate named by the extern
+    /// crate referenced above. If false, then this crate is a dep
+    /// of the crate.
+    #[inline]
+    pub fn is_direct(&self) -> bool {
+        self.dependency_of == LOCAL_CRATE
+    }
+
+    #[inline]
+    pub fn rank(&self) -> impl PartialOrd {
+        // Prefer:
+        // - direct extern crate to indirect
+        // - shorter paths to longer
+        (self.is_direct(), !self.path_len)
+    }
+}
+
+#[derive(Copy, Clone, Debug, HashStable_Generic)]
+pub enum ExternCrateSource {
+    /// Crate is loaded by `extern crate`.
+    Extern(
+        /// def_id of the item in the current crate that caused
+        /// this crate to be loaded; note that there could be multiple
+        /// such ids
+        DefId,
+    ),
+    /// Crate is implicitly loaded by a path resolving through extern prelude.
+    Path,
+}
+
+/// The backend's way to give the crate store access to the metadata in a library.
+/// Note that it returns the raw metadata bytes stored in the library file, whether
+/// it is compressed, uncompressed, some weird mix, etc.
+/// rmeta files are backend independent and not handled here.
+///
+/// At the time of this writing, there is only one backend and one way to store
+/// metadata in library -- this trait just serves to decouple rustc_metadata from
+/// the archive reader, which depends on LLVM.
+pub trait MetadataLoader {
+    fn get_rlib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String>;
+    fn get_dylib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String>;
+}
+
+pub type MetadataLoaderDyn = dyn MetadataLoader + Sync;
+
+/// A store of Rust crates, through which their metadata can be accessed.
+///
+/// Note that this trait should probably not be expanding today. All new
+/// functionality should be driven through queries instead!
+///
+/// If you find a method on this trait named `{name}_untracked` it signifies
+/// that it's *not* tracked for dependency information throughout compilation
+/// (it'd break incremental compilation) and should only be called pre-HIR (e.g.
+/// during resolve)
+pub trait CrateStore: std::fmt::Debug {
+    fn as_any(&self) -> &dyn Any;
+
+    // Foreign definitions.
+    // This information is safe to access, since it's hashed as part of the DefPathHash, which incr.
+    // comp. uses to identify a DefId.
+    fn def_key(&self, def: DefId) -> DefKey;
+    fn def_path(&self, def: DefId) -> DefPath;
+    fn def_path_hash(&self, def: DefId) -> DefPathHash;
+
+    // This information is safe to access, since it's hashed as part of the StableCrateId, which
+    // incr.  comp. uses to identify a CrateNum.
+    fn crate_name(&self, cnum: CrateNum) -> Symbol;
+    fn stable_crate_id(&self, cnum: CrateNum) -> StableCrateId;
+    fn stable_crate_id_to_crate_num(&self, stable_crate_id: StableCrateId) -> CrateNum;
+
+    /// Fetch a DefId from a DefPathHash for a foreign crate.
+    fn def_path_hash_to_def_id(&self, cnum: CrateNum, hash: DefPathHash) -> DefId;
+    fn expn_hash_to_expn_id(&self, cnum: CrateNum, index_guess: u32, hash: ExpnHash) -> ExpnId;
+}
+
+pub type CrateStoreDyn = dyn CrateStore + sync::Sync;
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 9a82ae3fc10..6c86f86ecd9 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -1,4 +1,5 @@
 #![feature(crate_visibility_modifier)]
+#![feature(min_specialization)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
 
@@ -14,6 +15,7 @@ pub mod parse;
 mod code_stats;
 #[macro_use]
 pub mod config;
+pub mod cstore;
 pub mod filesearch;
 mod options;
 pub mod search_paths;
@@ -28,4 +30,4 @@ pub use getopts;
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
 /// instead of implementing everything in `rustc_middle`.
-pub trait HashStableContext {}
+pub trait HashStableContext: rustc_ast::HashStableContext + rustc_hir::HashStableContext {}