Move ensure_sufficient_stack to data_structures

We anticipate this to have uses in all sorts of crates and keeping it in
`rustc_data_structures` enables access to it from more locations without
necessarily pulling in the large `librustc` crate.

Author: nagisa

Cargo.lock

@@ -3161,7 +3161,6 @@ checksum = "81dfcfbb0ddfd533abf8c076e3b49d1e5042d1962526a12ce2c66d514b24cca3"
 dependencies = [
  "rustc-ap-rustc_data_structures",
  "smallvec 1.0.0",
- "stacker",
 ]
 
 [[package]]
@@ -3706,6 +3705,7 @@ dependencies = [
  "serialize",
  "smallvec 1.0.0",
  "stable_deref_trait",
+ "stacker",
  "winapi 0.3.8",
 ]
 

src/librustc_ast_lowering/expr.rs

@@ -3,11 +3,11 @@ use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericAr
 use rustc_ast::ast::*;
 use rustc_ast::attr;
 use rustc_ast::ptr::P as AstP;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
-use rustc_middle::limits::ensure_sufficient_stack;
 use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
 use rustc_span::symbol::{sym, Symbol};
 

src/librustc_ast_lowering/pat.rs

@@ -2,9 +2,9 @@ use super::{ImplTraitContext, LoweringContext, ParamMode};
 
 use rustc_ast::ast::*;
 use rustc_ast::ptr::P;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
-use rustc_middle::limits::ensure_sufficient_stack;
 use rustc_span::{source_map::Spanned, Span};
 
 impl<'a, 'hir> LoweringContext<'a, 'hir> {

src/librustc_data_structures/Cargo.toml

@@ -28,6 +28,7 @@ rustc_index = { path = "../librustc_index", package = "rustc_index" }
 bitflags = "1.2.1"
 measureme = "0.7.1"
 libc = "0.2"
+stacker = "0.1.6"
 
 [dependencies.parking_lot]
 version = "0.10"

src/librustc_data_structures/lib.rs

@@ -80,6 +80,7 @@ pub mod stable_set;
 #[macro_use]
 pub mod stable_hasher;
 pub mod sharded;
+pub mod stack;
 pub mod sync;
 pub mod thin_vec;
 pub mod tiny_list;

src/librustc_data_structures/stack.rs

@@ -0,0 +1,17 @@
+// This is the amount of bytes that need to be left on the stack before increasing the size.
+// It must be at least as large as the stack required by any code that does not call
+// `ensure_sufficient_stack`.
+const RED_ZONE: usize = 100 * 1024; // 100k
+
+// Only the first stack that is pushed, grows exponentially (2^n * STACK_PER_RECURSION) from then
+// on. This flag has performance relevant characteristics. Don't set it too high.
+const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB
+
+/// Grows the stack on demand to prevent stack overflow. Call this in strategic locations
+/// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit
+/// from this.
+///
+/// Should not be sprinkled around carelessly, as it causes a little bit of overhead.
+pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
+    stacker::maybe_grow(RED_ZONE, STACK_PER_RECURSION, f)
+}

src/librustc_middle/Cargo.toml

@@ -34,4 +34,3 @@ byteorder = { version = "1.3" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 measureme = "0.7.1"
 rustc_session = { path = "../librustc_session" }
-stacker = "0.1.6"

src/librustc_middle/middle/limits.rs

@@ -13,24 +13,6 @@ use rustc_span::symbol::{sym, Symbol};
 
 use std::num::IntErrorKind;
 
-// This is the amount of bytes that need to be left on the stack before increasing the size.
-// It must be at least as large as the stack required by any code that does not call
-// `ensure_sufficient_stack`.
-const RED_ZONE: usize = 100 * 1024; // 100k
-
-// Ony the first stack that is pushed, grows exponentially (2^n * STACK_PER_RECURSION) from then
-// on. This flag has performance relevant characteristics. Don't set it too high.
-const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB
-
-/// Grows the stack on demand to prevent stack overflow. Call this in strategic locations
-/// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit
-/// from this.
-///
-/// Should not be sprinkled around carelessly, as it causes a little bit of overhead.
-pub fn ensure_sufficient_stack<R, F: FnOnce() -> R>(f: F) -> R {
-    stacker::maybe_grow(RED_ZONE, STACK_PER_RECURSION, f)
-}
-
 pub fn update_limits(sess: &Session, krate: &ast::Crate) {
     update_limit(sess, krate, &sess.recursion_limit, sym::recursion_limit, 128);
     update_limit(sess, krate, &sess.type_length_limit, sym::type_length_limit, 1048576);

src/librustc_middle/ty/inhabitedness/mod.rs

@@ -1,12 +1,12 @@
 pub use self::def_id_forest::DefIdForest;
 
-use crate::middle::limits::ensure_sufficient_stack;
 use crate::ty;
 use crate::ty::context::TyCtxt;
 use crate::ty::TyKind::*;
 use crate::ty::{AdtDef, FieldDef, Ty, TyS, VariantDef};
 use crate::ty::{AdtKind, Visibility};
 use crate::ty::{DefId, SubstsRef};
+use rustc_data_structures::stack::ensure_sufficient_stack;
 
 mod def_id_forest;
 

src/librustc_middle/ty/query/plumbing.rs

@@ -69,7 +69,7 @@ impl QueryContext for TyCtxt<'tcx> {
 
             // Use the `ImplicitCtxt` while we execute the query.
             tls::enter_context(&new_icx, |_| {
-                crate::middle::limits::ensure_sufficient_stack(|| compute(*self))
+                rustc_data_structures::stack::ensure_sufficient_stack(|| compute(*self))
             })
         })
     }