Rename and reorder lots of lifetimes.

- Replace non-standard names like 's, 'p, 'rg, 'ck, 'parent, 'this, and
  'me with vanilla 'a. These are cases where the original name isn't
  really any more informative than 'a.
- Replace names like 'cx, 'mir, and 'body with vanilla 'a when the lifetime
  applies to multiple fields and so the original lifetime name isn't
  really accurate.
- Put 'tcx last in lifetime lists, and 'a before 'b.

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -134,13 +134,12 @@ fn parse_attribute(attr: &Attribute) -> MirPhase {
     MirPhase::parse(dialect, phase)
 }
 
-struct ParseCtxt<'tcx, 'body> {
+struct ParseCtxt<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
-    thir: &'body Thir<'tcx>,
+    thir: &'a Thir<'tcx>,
     source_scope: SourceScope,
-
-    body: &'body mut Body<'tcx>,
+    body: &'a mut Body<'tcx>,
     local_map: FxHashMap<LocalVarId, Local>,
     block_map: FxHashMap<LocalVarId, BasicBlock>,
 }
@@ -151,7 +150,7 @@ struct ParseError {
     expected: String,
 }
 
-impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
+impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
     fn expr_error(&self, expr: ExprId, expected: &'static str) -> ParseError {
         let expr = &self.thir[expr];
         ParseError {

compiler/rustc_mir_build/src/build/custom/parse.rs

@@ -68,7 +68,7 @@ macro_rules! parse_by_kind {
 }
 pub(crate) use parse_by_kind;
 
-impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
+impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
     /// Expressions should only ever be matched on after preparsing them. This removes extra scopes
     /// we don't care about.
     fn preparse(&self, expr_id: ExprId) -> ExprId {

compiler/rustc_mir_build/src/build/custom/parse/instruction.rs

@@ -12,7 +12,7 @@ use super::{parse_by_kind, PResult, ParseCtxt};
 use crate::build::custom::ParseError;
 use crate::build::expr::as_constant::as_constant_inner;
 
-impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
+impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
     pub(crate) fn parse_statement(&self, expr_id: ExprId) -> PResult<StatementKind<'tcx>> {
         parse_by_kind!(self, expr_id, _, "statement",
             @call(mir_storage_live, args) => {