Rollup merge of rust-lang#66878 - Mark-Simulacrum:sess-decouple, r=Centril

Move Sessions into (new) librustc_session

This PR moves `ParseSess` and `Session` from their current locations into a new crate, `librustc_session`.

There are several intents behind this change. librustc is a very large crate, and we want to split it up over time -- this movement removes the sizeable session module from it. It also helps allow for future movement of things not coupled to TyCtxt but coupled to Session out of the crate.

This movement allows allows for a future follow-up PR which unifies Session and ParseSess, allowing for a single source of truth for APIs interested in global options throughout the compiler; the ParseSess is already created directly as a member of Session in the current compiler (i.e., we do not first construct a ParseSess and then move it into Session later in the compilation).

This PR intentionally avoids changing numerous imports throughout the tree to new locations of the moved types; this is needless noise and can be done as needed.

In the process of moving the sessions back, the lint system received an update as well -- notably, early buffered lints are no longer ad-hoc declared as enum pairs and later associated with proper lint declarations. They are still separately handled (buffered), it is a little unclear whether this is truly necessary, but regardless is left for future PRs.

Many of the types moved back are sort of ad-hoc placed into the same crate (librustc_session) instead of creating other crates; it's unclear whether this is actually a good thing, but it seemed better than creating numerous tiny crates which served no purpose on their own.

Author: Centril

Cargo.lock

@@ -3205,6 +3205,7 @@ dependencies = [
  "rustc_fs_util",
  "rustc_index",
  "rustc_macros",
+ "rustc_session",
  "rustc_target",
  "scoped-tls",
  "serialize",
@@ -3518,6 +3519,7 @@ dependencies = [
  "rustc_fs_util",
  "rustc_incremental",
  "rustc_index",
+ "rustc_session",
  "rustc_target",
  "serialize",
  "syntax",
@@ -3634,6 +3636,7 @@ dependencies = [
  "rustc",
  "rustc_data_structures",
  "rustc_fs_util",
+ "rustc_session",
  "serialize",
  "syntax",
  "syntax_pos",
@@ -3697,6 +3700,7 @@ dependencies = [
  "rustc_error_codes",
  "rustc_feature",
  "rustc_index",
+ "rustc_session",
  "rustc_target",
  "syntax",
  "syntax_pos",
@@ -3884,6 +3888,22 @@ dependencies = [
  "syntax_pos",
 ]
 
+[[package]]
+name = "rustc_session"
+version = "0.0.0"
+dependencies = [
+ "log",
+ "num_cpus",
+ "rustc_data_structures",
+ "rustc_errors",
+ "rustc_feature",
+ "rustc_fs_util",
+ "rustc_index",
+ "rustc_target",
+ "serialize",
+ "syntax_pos",
+]
+
 [[package]]
 name = "rustc_target"
 version = "0.0.0"
@@ -4463,6 +4483,7 @@ dependencies = [
  "rustc_index",
  "rustc_lexer",
  "rustc_macros",
+ "rustc_session",
  "scoped-tls",
  "serialize",
  "smallvec 1.0.0",

src/librustc/Cargo.toml

@@ -39,3 +39,4 @@ rustc_fs_util = { path = "../librustc_fs_util" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 measureme = "0.4"
 rustc_error_codes = { path = "../librustc_error_codes" }
+rustc_session = { path = "../librustc_session" }

src/librustc/dep_graph/mod.rs

@@ -5,7 +5,6 @@ mod prev;
 mod query;
 mod safe;
 mod serialized;
-pub mod cgu_reuse_tracker;
 
 pub use self::dep_node::{DepNode, DepKind, DepConstructor, WorkProductId, RecoverKey, label_strs};
 pub use self::graph::{DepGraph, WorkProduct, DepNodeIndex, DepNodeColor, TaskDeps, hash_result};

src/librustc/lib.rs

@@ -64,7 +64,6 @@
 #![recursion_limit="512"]
 
 #[macro_use] extern crate bitflags;
-extern crate getopts;
 #[macro_use] extern crate scoped_tls;
 #[cfg(windows)]
 extern crate libc;
@@ -74,10 +73,6 @@ extern crate libc;
 #[macro_use] extern crate syntax;
 #[macro_use] extern crate smallvec;
 
-// Use the test crate here so we depend on getopts through it. This allow tools to link to both
-// librustc_driver and libtest.
-extern crate test as _;
-
 #[cfg(test)]
 mod tests;
 
@@ -113,7 +108,7 @@ pub mod middle {
 }
 
 pub mod mir;
-pub mod session;
+pub use rustc_session as session;
 pub mod traits;
 pub mod ty;
 

src/librustc/lint/builtin.rs

@@ -12,6 +12,8 @@ use syntax::ast;
 use syntax::edition::Edition;
 use syntax::source_map::Span;
 use syntax::symbol::Symbol;
+use syntax::early_buffered_lints::{ILL_FORMED_ATTRIBUTE_INPUT, META_VARIABLE_MISUSE};
+use rustc_session::declare_lint;
 
 declare_lint! {
     pub EXCEEDING_BITSHIFTS,
@@ -404,31 +406,6 @@ declare_lint! {
     };
 }
 
-/// Some lints that are buffered from `libsyntax`. See `syntax::early_buffered_lints`.
-pub mod parser {
-    declare_lint! {
-        pub ILL_FORMED_ATTRIBUTE_INPUT,
-        Deny,
-        "ill-formed attribute inputs that were previously accepted and used in practice",
-        @future_incompatible = super::FutureIncompatibleInfo {
-            reference: "issue #57571 <https://github.com/rust-lang/rust/issues/57571>",
-            edition: None,
-        };
-    }
-
-    declare_lint! {
-        pub META_VARIABLE_MISUSE,
-        Allow,
-        "possible meta-variable misuse at macro definition"
-    }
-
-    declare_lint! {
-        pub INCOMPLETE_INCLUDE,
-        Deny,
-        "trailing content in included file"
-    }
-}
-
 declare_lint! {
     pub DEPRECATED_IN_FUTURE,
     Allow,
@@ -520,8 +497,8 @@ declare_lint_pass! {
         PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
         MACRO_USE_EXTERN_CRATE,
         MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
-        parser::ILL_FORMED_ATTRIBUTE_INPUT,
-        parser::META_VARIABLE_MISUSE,
+        ILL_FORMED_ATTRIBUTE_INPUT,
+        META_VARIABLE_MISUSE,
         DEPRECATED_IN_FUTURE,
         AMBIGUOUS_ASSOCIATED_ITEMS,
         MUTABLE_BORROW_RESERVATION_CONFLICT,

src/librustc/lint/internal.rs

@@ -9,6 +9,7 @@ use errors::Applicability;
 use rustc_data_structures::fx::FxHashMap;
 use syntax::ast::{Ident, Item, ItemKind};
 use syntax::symbol::{sym, Symbol};
+use rustc_session::declare_tool_lint;
 
 declare_tool_lint! {
     pub rustc::DEFAULT_HASH_TYPES,

src/librustc/lint/levels.rs

@@ -8,7 +8,7 @@ use crate::lint::{self, Lint, LintId, Level, LintSource};
 use crate::session::Session;
 use crate::util::nodemap::FxHashMap;
 use errors::{Applicability, DiagnosticBuilder};
-use rustc_data_structures::stable_hasher::{HashStable, ToStableHashKey, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use syntax::ast;
 use syntax::attr;
 use syntax::feature_gate;
@@ -93,7 +93,7 @@ impl LintLevelSets {
 
         // If `level` is none then we actually assume the default level for this
         // lint.
-        let mut level = level.unwrap_or_else(|| lint.default_level(sess));
+        let mut level = level.unwrap_or_else(|| lint.default_level(sess.edition()));
 
         // If we're about to issue a warning, check at the last minute for any
         // directives against the warnings "lint". If, for example, there's an
@@ -566,19 +566,3 @@ impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
         })
     }
 }
-
-impl<HCX> HashStable<HCX> for LintId {
-    #[inline]
-    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
-        self.lint_name_raw().hash_stable(hcx, hasher);
-    }
-}
-
-impl<HCX> ToStableHashKey<HCX> for LintId {
-    type KeyType = &'static str;
-
-    #[inline]
-    fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
-        self.lint_name_raw()
-    }
-}