Rollup merge of #122487 - GuillaumeGomez:rename-stmtkind-local, r=oli-obk

Rename `StmtKind::Local` variant into `StmtKind::Let`

It comes from this [discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Improve.20naming.20of.20.60ExprKind.3A.3ALet.60.3F).

Starting point was:

> I often end up looking at [ExprKind::Let](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/enum.ExprKind.html#variant.Let) instead of Local because of the name. I think renaming it (both the `ExprKind` variant and the Let struct) to `LetPattern` or LetPat could improve the situation as I'm not sure I'm not the only one encountering this issue.

And then it evolved into:

> It's already `Expr::Let` instead of `StmtKind::Local`. Counterproposal: rename `StmtKind::Local` to `StmtKind::Let`.

The goal here is to clear this confusion.

r? `@oli-obk`

compiler/rustc_passes/src/check_attr.rs

@@ -2444,7 +2444,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
 
     fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
         // When checking statements ignore expressions, they will be checked later.
-        if let hir::StmtKind::Local(l) = stmt.kind {
+        if let hir::StmtKind::Let(l) = stmt.kind {
             self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
         }
         intravisit::walk_stmt(self, stmt)

compiler/rustc_passes/src/hir_stats.rs

@@ -277,7 +277,7 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
     fn visit_stmt(&mut self, s: &'v hir::Stmt<'v>) {
         record_variants!(
             (self, s, s.kind, Id::Node(s.hir_id), hir, Stmt, StmtKind),
-            [Local, Item, Expr, Semi]
+            [Let, Item, Expr, Semi]
         );
         hir_visit::walk_stmt(self, s)
     }
@@ -539,7 +539,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
     fn visit_stmt(&mut self, s: &'v ast::Stmt) {
         record_variants!(
             (self, s, s.kind, Id::None, ast, Stmt, StmtKind),
-            [Local, Item, Expr, Semi, Empty, MacCall]
+            [Let, Item, Expr, Semi, Empty, MacCall]
         );
         ast_visit::walk_stmt(self, s)
     }

compiler/rustc_passes/src/liveness.rs

@@ -771,7 +771,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
 
     fn propagate_through_stmt(&mut self, stmt: &hir::Stmt<'_>, succ: LiveNode) -> LiveNode {
         match stmt.kind {
-            hir::StmtKind::Local(local) => {
+            hir::StmtKind::Let(local) => {
                 // Note: we mark the variable as defined regardless of whether
                 // there is an initializer. Initially I had thought to only mark
                 // the live variable as defined if it was initialized, and then we

compiler/rustc_passes/src/naked_functions.rs

@@ -280,7 +280,7 @@ impl<'tcx> Visitor<'tcx> for CheckInlineAssembly<'tcx> {
     fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
         match stmt.kind {
             StmtKind::Item(..) => {}
-            StmtKind::Local(..) => {
+            StmtKind::Let(..) => {
                 self.items.push((ItemKind::NonAsm, stmt.span));
             }
             StmtKind::Expr(expr) | StmtKind::Semi(expr) => {