Reduce pub exposure.

A lot of errors don't need to be visible outside the crate, and some
other things as well.

compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs

@@ -179,18 +179,18 @@ fn take_condition(
     }
 }
 
-pub struct MCDCInfoBuilder {
+pub(crate) struct MCDCInfoBuilder {
     branch_spans: Vec<MCDCBranchSpan>,
     decision_spans: Vec<MCDCDecisionSpan>,
     state: MCDCState,
 }
 
 impl MCDCInfoBuilder {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         Self { branch_spans: vec![], decision_spans: vec![], state: MCDCState::new() }
     }
 
-    pub fn visit_evaluated_condition(
+    pub(crate) fn visit_evaluated_condition(
         &mut self,
         tcx: TyCtxt<'_>,
         source_info: SourceInfo,
@@ -243,7 +243,7 @@ pub fn visit_evaluated_condition(
         });
     }
 
-    pub fn into_done(self) -> (Vec<MCDCDecisionSpan>, Vec<MCDCBranchSpan>) {
+    pub(crate) fn into_done(self) -> (Vec<MCDCDecisionSpan>, Vec<MCDCBranchSpan>) {
         (self.decision_spans, self.branch_spans)
     }
 }

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

@@ -91,7 +91,7 @@ fn statement_as_expr(&self, stmt_id: StmtId) -> PResult<ExprId> {
         }
     }
 
-    pub fn parse_args(&mut self, params: &IndexSlice<ParamId, Param<'tcx>>) -> PResult<()> {
+    pub(crate) fn parse_args(&mut self, params: &IndexSlice<ParamId, Param<'tcx>>) -> PResult<()> {
         for param in params.iter() {
             let (var, span) = {
                 let pat = param.pat.as_ref().unwrap();
@@ -149,7 +149,7 @@ pub fn parse_args(&mut self, params: &IndexSlice<ParamId, Param<'tcx>>) -> PResu
     ///
     /// This allows us to easily parse the basic blocks declarations, local declarations, and
     /// basic block definitions in order.
-    pub fn parse_body(&mut self, expr_id: ExprId) -> PResult<()> {
+    pub(crate) fn parse_body(&mut self, expr_id: ExprId) -> PResult<()> {
         let body = parse_by_kind!(self, expr_id, _, "whole body",
             ExprKind::Block { block } => self.thir[*block].expr.unwrap(),
         );

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

@@ -12,7 +12,7 @@
 use super::{parse_by_kind, PResult, ParseCtxt};
 
 impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
-    pub fn parse_statement(&self, expr_id: ExprId) -> PResult<StatementKind<'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) => {
                 Ok(StatementKind::StorageLive(self.parse_local(args[0])?))
@@ -46,7 +46,7 @@ pub fn parse_statement(&self, expr_id: ExprId) -> PResult<StatementKind<'tcx>> {
         )
     }
 
-    pub fn parse_terminator(&self, expr_id: ExprId) -> PResult<TerminatorKind<'tcx>> {
+    pub(crate) fn parse_terminator(&self, expr_id: ExprId) -> PResult<TerminatorKind<'tcx>> {
         parse_by_kind!(self, expr_id, expr, "terminator",
             @call(mir_return, _args) => {
                 Ok(TerminatorKind::Return)
@@ -261,7 +261,7 @@ fn parse_rvalue(&self, expr_id: ExprId) -> PResult<Rvalue<'tcx>> {
         )
     }
 
-    pub fn parse_operand(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> {
+    pub(crate) fn parse_operand(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> {
         parse_by_kind!(self, expr_id, expr, "operand",
             @call(mir_move, args) => self.parse_place(args[0]).map(Operand::Move),
             @call(mir_static, args) => self.parse_static(args[0]),

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -39,7 +39,7 @@ pub(crate) fn as_constant(&mut self, expr: &Expr<'tcx>) -> ConstOperand<'tcx> {
     }
 }
 
-pub fn as_constant_inner<'tcx>(
+pub(crate) fn as_constant_inner<'tcx>(
     expr: &Expr<'tcx>,
     push_cuta: impl FnMut(&Box<CanonicalUserType<'tcx>>) -> Option<UserTypeAnnotationIndex>,
     tcx: TyCtxt<'tcx>,

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

@@ -62,9 +62,9 @@
 
 pub(crate) mod as_constant;
 mod as_operand;
-pub mod as_place;
+pub(crate) mod as_place;
 mod as_rvalue;
 mod as_temp;
-pub mod category;
+pub(crate) mod category;
 mod into;
 mod stmt;

compiler/rustc_mir_build/src/build/matches/util.rs

@@ -456,7 +456,7 @@ fn visit_binding(&mut self, Binding { source, .. }: &Binding<'tcx>) {
 }
 
 #[must_use]
-pub fn ref_pat_borrow_kind(ref_mutability: Mutability) -> BorrowKind {
+pub(crate) fn ref_pat_borrow_kind(ref_mutability: Mutability) -> BorrowKind {
     match ref_mutability {
         Mutability::Mut => BorrowKind::Mut { kind: MutBorrowKind::Default },
         Mutability::Not => BorrowKind::Shared,

compiler/rustc_mir_build/src/build/scope.rs

@@ -97,7 +97,7 @@
 use tracing::{debug, instrument};
 
 #[derive(Debug)]
-pub struct Scopes<'tcx> {
+pub(crate) struct Scopes<'tcx> {
     scopes: Vec<Scope>,
 
     /// The current set of breakable scopes. See module comment for more details.

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -597,7 +597,7 @@ enum UnsafeOpKind {
 use UnsafeOpKind::*;
 
 impl UnsafeOpKind {
-    pub fn emit_unsafe_op_in_unsafe_fn_lint(
+    fn emit_unsafe_op_in_unsafe_fn_lint(
         &self,
         tcx: TyCtxt<'_>,
         hir_id: HirId,
@@ -737,7 +737,7 @@ pub fn emit_unsafe_op_in_unsafe_fn_lint(
         }
     }
 
-    pub fn emit_requires_unsafe_err(
+    fn emit_requires_unsafe_err(
         &self,
         tcx: TyCtxt<'_>,
         span: Span,