Auto merge of #61817 - eddyb:begone-gcx-attempt-2, r=oli-obk

Unify all uses of 'gcx and 'tcx.

This is made possible by @Zoxc landing #57214 (see #57214 (comment) for the decision).

A bit of context for the approach: just like #61722, this is *not* how I originally intended to go about this, but @Zoxc and my own experimentation independently resulted in the same conclusion:
The interim alias `type TyCx<'tcx> = TyCtxt<'tcx, 'tcx>;` attempt required more work (adding `use`s), even only for handling the `TyCtxt<'tcx, 'tcx>` case and not the general `TyCtxt<'gcx, 'tcx>` one.

What this PR is based on is the realization that `'gcx` is a special-enough name that it can be replaced, without caring for context, with `'tcx`, and then repetitions of the name `'tcx` be compacted away.
After that, only a small number of error categories remained, each category easily dealt with with either more mass replacements (e.g. `TyCtxt<'tcx, '_>` -> `TyCtxt<'tcx>`) or by hand.

For the `rustfmt` commit, I used rust-lang/rustfmt#1324 (comment), and manually filtered out some noise, like in #61735 and #61722, and like the latter, there was also a weird bug to work around.
It should be reviewed separately, and dropped if unwanted (in this PR it's pretty significant).

cc @rust-lang/compiler r? @nikomatsakis

src/librustc/cfg/construct.rs

@@ -8,7 +8,7 @@ use crate::hir::{self, PatKind};
 use crate::hir::def_id::DefId;
 
 struct CFGBuilder<'a, 'tcx: 'a> {
-    tcx: TyCtxt<'tcx, 'tcx>,
+    tcx: TyCtxt<'tcx>,
     owner_def_id: DefId,
     tables: &'a ty::TypeckTables<'tcx>,
     graph: CFGGraph,
@@ -30,7 +30,7 @@ struct LoopScope {
     break_index: CFGIndex,    // where to go on a `break`
 }
 
-pub fn construct<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, body: &hir::Body) -> CFG {
+pub fn construct<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body) -> CFG {
     let mut graph = graph::Graph::new();
     let entry = graph.add_node(CFGNodeData::Entry);
 

src/librustc/cfg/graphviz.rs

@@ -12,7 +12,7 @@ pub type Node<'a> = (cfg::CFGIndex, &'a cfg::CFGNode);
 pub type Edge<'a> = &'a cfg::CFGEdge;
 
 pub struct LabelledCFG<'a, 'tcx: 'a> {
-    pub tcx: TyCtxt<'tcx, 'tcx>,
+    pub tcx: TyCtxt<'tcx>,
     pub cfg: &'a cfg::CFG,
     pub name: String,
     /// `labelled_edges` controls whether we emit labels on the edges

src/librustc/cfg/mod.rs

@@ -49,7 +49,7 @@ pub type CFGNode = graph::Node<CFGNodeData>;
 pub type CFGEdge = graph::Edge<CFGEdgeData>;
 
 impl CFG {
-    pub fn new<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, body: &hir::Body) -> CFG {
+    pub fn new<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body) -> CFG {
         construct::construct(tcx, body)
     }
 

src/librustc/dep_graph/dep_node.rs

@@ -204,10 +204,10 @@ macro_rules! define_dep_nodes {
         impl DepNode {
             #[allow(unreachable_code, non_snake_case)]
             #[inline(always)]
-            pub fn new<'a, 'gcx, 'tcx>(tcx: TyCtxt<'gcx, 'tcx>,
-                                       dep: DepConstructor<'gcx>)
+            pub fn new<'a, 'tcx>(tcx: TyCtxt<'tcx>,
+                                       dep: DepConstructor<'tcx>)
                                        -> DepNode
-                where 'gcx: 'a + 'tcx,
+                where 'tcx: 'a,
                       'tcx: 'a
             {
                 match dep {
@@ -307,7 +307,7 @@ macro_rules! define_dep_nodes {
             /// refers to something from the previous compilation session that
             /// has been removed.
             #[inline]
-            pub fn extract_def_id(&self, tcx: TyCtxt<'_, '_>) -> Option<DefId> {
+            pub fn extract_def_id(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
                 if self.kind.can_reconstruct_query_key() {
                     let def_path_hash = DefPathHash(self.hash);
                     tcx.def_path_hash_to_def_id.as_ref()?
@@ -400,7 +400,7 @@ impl DefPathHash {
 
 impl DefId {
     #[inline(always)]
-    pub fn to_dep_node(self, tcx: TyCtxt<'_, '_>, kind: DepKind) -> DepNode {
+    pub fn to_dep_node(self, tcx: TyCtxt<'_>, kind: DepKind) -> DepNode {
         DepNode::from_def_path_hash(kind, tcx.def_path_hash(self))
     }
 }
@@ -442,50 +442,50 @@ rustc_dep_node_append!([define_dep_nodes!][ <'tcx>
 ]);
 
 pub trait RecoverKey<'tcx>: Sized {
-    fn recover(tcx: TyCtxt<'tcx, 'tcx>, dep_node: &DepNode) -> Option<Self>;
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self>;
 }
 
 impl RecoverKey<'tcx> for CrateNum {
-    fn recover(tcx: TyCtxt<'tcx, 'tcx>, dep_node: &DepNode) -> Option<Self> {
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
         dep_node.extract_def_id(tcx).map(|id| id.krate)
     }
 }
 
 impl RecoverKey<'tcx> for DefId {
-    fn recover(tcx: TyCtxt<'tcx, 'tcx>, dep_node: &DepNode) -> Option<Self> {
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
         dep_node.extract_def_id(tcx)
     }
 }
 
 impl RecoverKey<'tcx> for DefIndex {
-    fn recover(tcx: TyCtxt<'tcx, 'tcx>, dep_node: &DepNode) -> Option<Self> {
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
         dep_node.extract_def_id(tcx).map(|id| id.index)
     }
 }
 
-trait DepNodeParams<'gcx: 'tcx, 'tcx>: fmt::Debug {
+trait DepNodeParams<'tcx>: fmt::Debug {
     const CAN_RECONSTRUCT_QUERY_KEY: bool;
 
     /// This method turns the parameters of a DepNodeConstructor into an opaque
     /// Fingerprint to be used in DepNode.
     /// Not all DepNodeParams support being turned into a Fingerprint (they
     /// don't need to if the corresponding DepNode is anonymous).
-    fn to_fingerprint(&self, _: TyCtxt<'gcx, 'tcx>) -> Fingerprint {
+    fn to_fingerprint(&self, _: TyCtxt<'tcx>) -> Fingerprint {
         panic!("Not implemented. Accidentally called on anonymous node?")
     }
 
-    fn to_debug_str(&self, _: TyCtxt<'gcx, 'tcx>) -> String {
+    fn to_debug_str(&self, _: TyCtxt<'tcx>) -> String {
         format!("{:?}", self)
     }
 }
 
-impl<'gcx: 'tcx, 'tcx, T> DepNodeParams<'gcx, 'tcx> for T
+impl<'tcx, T> DepNodeParams<'tcx> for T
 where
     T: HashStable<StableHashingContext<'tcx>> + fmt::Debug,
 {
     default const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
-    default fn to_fingerprint(&self, tcx: TyCtxt<'gcx, 'tcx>) -> Fingerprint {
+    default fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint {
         let mut hcx = tcx.create_stable_hashing_context();
         let mut hasher = StableHasher::new();
 
@@ -494,58 +494,58 @@ where
         hasher.finish()
     }
 
-    default fn to_debug_str(&self, _: TyCtxt<'gcx, 'tcx>) -> String {
+    default fn to_debug_str(&self, _: TyCtxt<'tcx>) -> String {
         format!("{:?}", *self)
     }
 }
 
-impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for DefId {
+impl<'tcx> DepNodeParams<'tcx> for DefId {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = true;
 
-    fn to_fingerprint(&self, tcx: TyCtxt<'_, '_>) -> Fingerprint {
+    fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         tcx.def_path_hash(*self).0
     }
 
-    fn to_debug_str(&self, tcx: TyCtxt<'gcx, 'tcx>) -> String {
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
         tcx.def_path_str(*self)
     }
 }
 
-impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for DefIndex {
+impl<'tcx> DepNodeParams<'tcx> for DefIndex {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = true;
 
-    fn to_fingerprint(&self, tcx: TyCtxt<'_, '_>) -> Fingerprint {
+    fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         tcx.hir().definitions().def_path_hash(*self).0
     }
 
-    fn to_debug_str(&self, tcx: TyCtxt<'gcx, 'tcx>) -> String {
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
         tcx.def_path_str(DefId::local(*self))
     }
 }
 
-impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for CrateNum {
+impl<'tcx> DepNodeParams<'tcx> for CrateNum {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = true;
 
-    fn to_fingerprint(&self, tcx: TyCtxt<'_, '_>) -> Fingerprint {
+    fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         let def_id = DefId {
             krate: *self,
             index: CRATE_DEF_INDEX,
         };
         tcx.def_path_hash(def_id).0
     }
 
-    fn to_debug_str(&self, tcx: TyCtxt<'gcx, 'tcx>) -> String {
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
         tcx.crate_name(*self).as_str().to_string()
     }
 }
 
-impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for (DefId, DefId) {
+impl<'tcx> DepNodeParams<'tcx> for (DefId, DefId) {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
     // We actually would not need to specialize the implementation of this
     // method but it's faster to combine the hashes than to instantiate a full
     // hashing context and stable-hashing state.
-    fn to_fingerprint(&self, tcx: TyCtxt<'_, '_>) -> Fingerprint {
+    fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         let (def_id_0, def_id_1) = *self;
 
         let def_path_hash_0 = tcx.def_path_hash(def_id_0);
@@ -554,7 +554,7 @@ impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for (DefId, DefId) {
         def_path_hash_0.0.combine(def_path_hash_1.0)
     }
 
-    fn to_debug_str(&self, tcx: TyCtxt<'gcx, 'tcx>) -> String {
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
         let (def_id_0, def_id_1) = *self;
 
         format!("({}, {})",
@@ -563,13 +563,13 @@ impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for (DefId, DefId) {
     }
 }
 
-impl<'gcx: 'tcx, 'tcx> DepNodeParams<'gcx, 'tcx> for HirId {
+impl<'tcx> DepNodeParams<'tcx> for HirId {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
     // We actually would not need to specialize the implementation of this
     // method but it's faster to combine the hashes than to instantiate a full
     // hashing context and stable-hashing state.
-    fn to_fingerprint(&self, tcx: TyCtxt<'_, '_>) -> Fingerprint {
+    fn to_fingerprint(&self, tcx: TyCtxt<'_>) -> Fingerprint {
         let HirId {
             owner,
             local_id,

src/librustc/dep_graph/graph.rs

@@ -557,7 +557,7 @@ impl DepGraph {
     /// a node index can be found for that node.
     pub fn try_mark_green_and_read(
         &self,
-        tcx: TyCtxt<'_, '_>,
+        tcx: TyCtxt<'_>,
         dep_node: &DepNode,
     ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
         self.try_mark_green(tcx, dep_node).map(|(prev_index, dep_node_index)| {
@@ -569,7 +569,7 @@ impl DepGraph {
 
     pub fn try_mark_green(
         &self,
-        tcx: TyCtxt<'_, '_>,
+        tcx: TyCtxt<'_>,
         dep_node: &DepNode,
     ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
         debug_assert!(!dep_node.kind.is_eval_always());
@@ -603,7 +603,7 @@ impl DepGraph {
     /// Try to mark a dep-node which existed in the previous compilation session as green.
     fn try_mark_previous_green<'tcx>(
         &self,
-        tcx: TyCtxt<'tcx, 'tcx>,
+        tcx: TyCtxt<'tcx>,
         data: &DepGraphData,
         prev_dep_node_index: SerializedDepNodeIndex,
         dep_node: &DepNode,
@@ -790,7 +790,7 @@ impl DepGraph {
     #[inline(never)]
     fn emit_diagnostics<'tcx>(
         &self,
-        tcx: TyCtxt<'tcx, 'tcx>,
+        tcx: TyCtxt<'tcx>,
         data: &DepGraphData,
         dep_node_index: DepNodeIndex,
         did_allocation: bool,
@@ -841,7 +841,7 @@ impl DepGraph {
     //
     // This method will only load queries that will end up in the disk cache.
     // Other queries will not be executed.
-    pub fn exec_cache_promotions<'tcx>(&self, tcx: TyCtxt<'tcx, 'tcx>) {
+    pub fn exec_cache_promotions<'tcx>(&self, tcx: TyCtxt<'tcx>) {
         let green_nodes: Vec<DepNode> = {
             let data = self.data.as_ref().unwrap();
             data.colors.values.indices().filter_map(|prev_index| {

src/librustc/dep_graph/safe.rs

@@ -33,7 +33,7 @@ impl DepGraphSafe for DefId {
 
 /// The type context itself can be used to access all kinds of tracked
 /// state, but those accesses should always generate read events.
-impl<'gcx, 'tcx> DepGraphSafe for TyCtxt<'gcx, 'tcx> {}
+impl<'tcx> DepGraphSafe for TyCtxt<'tcx> {}
 
 /// Tuples make it easy to build up state.
 impl<A, B> DepGraphSafe for (A, B)

src/librustc/hir/check_attr.rs

@@ -88,7 +88,7 @@ impl Target {
 }
 
 struct CheckAttrVisitor<'tcx> {
-    tcx: TyCtxt<'tcx, 'tcx>,
+    tcx: TyCtxt<'tcx>,
 }
 
 impl CheckAttrVisitor<'tcx> {
@@ -347,7 +347,7 @@ fn is_c_like_enum(item: &hir::Item) -> bool {
     }
 }
 
-fn check_mod_attrs<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, module_def_id: DefId) {
+fn check_mod_attrs<'tcx>(tcx: TyCtxt<'tcx>, module_def_id: DefId) {
     tcx.hir().visit_item_likes_in_module(
         module_def_id,
         &mut CheckAttrVisitor { tcx }.as_deep_visitor()

src/librustc/hir/def_id.rs

@@ -177,7 +177,7 @@ impl DefId {
         LocalDefId::from_def_id(self)
     }
 
-    pub fn describe_as_module(&self, tcx: TyCtxt<'_, '_>) -> String {
+    pub fn describe_as_module(&self, tcx: TyCtxt<'_>) -> String {
         if self.is_local() && self.index == CRATE_DEF_INDEX {
             format!("top-level module")
         } else {