Rollup merge of #108154 - scottmcm:start-block-cleanup, r=compiler-errors

`BasicBlock::new(0)` -> `START_BLOCK` [no functional changes]

compiler/rustc_const_eval/src/transform/promote_consts.rs

@@ -898,7 +898,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
         assert_eq!(self.new_block(), START_BLOCK);
         self.visit_rvalue(
             &mut rvalue,
-            Location { block: BasicBlock::new(0), statement_index: usize::MAX },
+            Location { block: START_BLOCK, statement_index: usize::MAX },
         );
 
         let span = self.promoted.span;

compiler/rustc_middle/src/mir/visit.rs

@@ -323,7 +323,7 @@ macro_rules! make_mir_visitor {
                     self.visit_source_scope($(& $mutability)? *parent_scope);
                 }
                 if let Some((callee, callsite_span)) = inlined {
-                    let location = START_BLOCK.start_location();
+                    let location = Location::START;
 
                     self.visit_span($(& $mutability)? *callsite_span);
 
@@ -837,7 +837,7 @@ macro_rules! make_mir_visitor {
                 } = var_debug_info;
 
                 self.visit_source_info(source_info);
-                let location = START_BLOCK.start_location();
+                let location = Location::START;
                 match value {
                     VarDebugInfoContents::Const(c) => self.visit_constant(c, location),
                     VarDebugInfoContents::Place(place) =>
@@ -1026,7 +1026,7 @@ macro_rules! super_body {
         $self.visit_span($(& $mutability)? $body.span);
 
         for const_ in &$($mutability)? $body.required_consts {
-            let location = START_BLOCK.start_location();
+            let location = Location::START;
             $self.visit_constant(const_, location);
         }
     }

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -136,8 +136,8 @@ use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::visit::{MutVisitor, PlaceContext, Visitor};
 use rustc_middle::mir::{dump_mir, PassWhere};
 use rustc_middle::mir::{
-    traversal, BasicBlock, Body, InlineAsmOperand, Local, LocalKind, Location, Operand, Place,
+    traversal, Body, InlineAsmOperand, Local, LocalKind, Location, Operand, Place, Rvalue,
-    Rvalue, Statement, StatementKind, TerminatorKind,
+    Statement, StatementKind, TerminatorKind,
 };
 use rustc_middle::ty::TyCtxt;
 use rustc_mir_dataflow::impls::MaybeLiveLocals;
@@ -468,7 +468,7 @@ impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
             // to reuse the allocation.
             write_info: write_info_alloc,
             // Doesn't matter what we put here, will be overwritten before being used
-            at: Location { block: BasicBlock::from_u32(0), statement_index: 0 },
+            at: Location::START,
         };
         this.internal_filter_liveness();
     }

compiler/rustc_mir_transform/src/generator.rs

@@ -487,7 +487,7 @@ fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
     let get_context_def_id = tcx.require_lang_item(LangItem::GetContext, None);
 
-    for bb in BasicBlock::new(0)..body.basic_blocks.next_index() {
+    for bb in START_BLOCK..body.basic_blocks.next_index() {
         let bb_data = &body[bb];
         if bb_data.is_cleanup {
             continue;
@@ -1255,7 +1255,7 @@ fn create_generator_resume_function<'tcx>(
     use rustc_middle::mir::AssertKind::{ResumedAfterPanic, ResumedAfterReturn};
 
     // Jump to the entry point on the unresumed
-    cases.insert(0, (UNRESUMED, BasicBlock::new(0)));
+    cases.insert(0, (UNRESUMED, START_BLOCK));
 
     // Panic when resumed on the returned or poisoned state
     let generator_kind = body.generator_kind().unwrap();
@@ -1481,7 +1481,7 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
 
         // When first entering the generator, move the resume argument into its new local.
         let source_info = SourceInfo::outermost(body.span);
-        let stmts = &mut body.basic_blocks_mut()[BasicBlock::new(0)].statements;
+        let stmts = &mut body.basic_blocks_mut()[START_BLOCK].statements;
         stmts.insert(
             0,
             Statement {

compiler/rustc_mir_transform/src/inline.rs

@@ -96,7 +96,7 @@ fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
         history: Vec::new(),
         changed: false,
     };
-    let blocks = BasicBlock::new(0)..body.basic_blocks.next_index();
+    let blocks = START_BLOCK..body.basic_blocks.next_index();
     this.process_blocks(body, blocks);
     this.changed
 }

compiler/rustc_mir_transform/src/simplify.rs

@@ -496,7 +496,7 @@ impl UsedLocals {
         self.increment = false;
 
         // The location of the statement is irrelevant.
-        let location = Location { block: START_BLOCK, statement_index: 0 };
+        let location = Location::START;
         self.visit_statement(statement, location);
     }