Ensure stack when type checking and building MIR for large if expressions

Author: kanru

src/librustc_mir_build/build/expr/into.rs

@@ -5,6 +5,7 @@ use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
 use crate::hair::*;
 use rustc_ast::ast::InlineAsmOptions;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation};
@@ -43,7 +44,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let block_and = match expr.kind {
             ExprKind::Scope { region_scope, lint_level, value } => {
                 let region_scope = (region_scope, source_info);
-                this.in_scope(region_scope, lint_level, |this| this.into(destination, block, value))
+                ensure_sufficient_stack(|| {
+                    this.in_scope(region_scope, lint_level, |this| {
+                        this.into(destination, block, value)
+                    })
+                })
             }
             ExprKind::Block { body: ast_block } => {
                 this.ast_block(destination, block, ast_block, source_info)

src/librustc_typeck/check/expr.rs

@@ -19,6 +19,7 @@ use crate::type_error_struct;
 use rustc_ast::ast;
 use rustc_ast::util::lev_distance::find_best_match_for_name;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::ErrorReported;
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, DiagnosticId};
 use rustc_hir as hir;
@@ -177,7 +178,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let old_diverges = self.diverges.replace(Diverges::Maybe);
         let old_has_errors = self.has_errors.replace(false);
 
-        let ty = self.check_expr_kind(expr, expected);
+        let ty = ensure_sufficient_stack(|| self.check_expr_kind(expr, expected));
 
         // Warn for non-block expressions with diverging children.
         match expr.kind {