Rollup merge of #136671 - nnethercote:middle-limits, r=Nadrieril

Overhaul `rustc_middle::limits`

In particular, to make `pattern_complexity` work more like other limits, which then enables some other simplifications.

r? ``@Nadrieril``

compiler/rustc_middle/messages.ftl

@@ -81,10 +81,6 @@ middle_failed_writing_file =
 middle_layout_references_error =
     the type has an unknown layout
 
-middle_limit_invalid =
-    `limit` must be a non-negative integer
-    .label = {$error_str}
-
 middle_opaque_hidden_type_mismatch =
     concrete type differs from previous defining opaque type use
     .label = expected `{$self_ty}`, got `{$other_ty}`

compiler/rustc_middle/src/error.rs

@@ -67,16 +67,6 @@ pub enum TypeMismatchReason {
     },
 }
 
-#[derive(Diagnostic)]
-#[diag(middle_limit_invalid)]
-pub(crate) struct LimitInvalid<'a> {
-    #[primary_span]
-    pub span: Span,
-    #[label]
-    pub value_span: Span,
-    pub error_str: &'a str,
-}
-
 #[derive(Diagnostic)]
 #[diag(middle_recursion_limit_reached)]
 #[help]

compiler/rustc_middle/src/middle/limits.rs

@@ -1,88 +0,0 @@
-//! Registering limits:
-//! * recursion_limit,
-//! * move_size_limit, and
-//! * type_length_limit
-//!
-//! There are various parts of the compiler that must impose arbitrary limits
-//! on how deeply they recurse to prevent stack overflow. Users can override
-//! this via an attribute on the crate like `#![recursion_limit="22"]`. This pass
-//! just peeks and looks for that attribute.
-
-use std::num::IntErrorKind;
-
-use rustc_ast::attr::AttributeExt;
-use rustc_session::{Limit, Limits, Session};
-use rustc_span::{Symbol, sym};
-
-use crate::error::LimitInvalid;
-use crate::query::Providers;
-
-pub fn provide(providers: &mut Providers) {
-    providers.limits = |tcx, ()| Limits {
-        recursion_limit: get_recursion_limit(tcx.hir().krate_attrs(), tcx.sess),
-        move_size_limit: get_limit(
-            tcx.hir().krate_attrs(),
-            tcx.sess,
-            sym::move_size_limit,
-            tcx.sess.opts.unstable_opts.move_size_limit.unwrap_or(0),
-        ),
-        type_length_limit: get_limit(
-            tcx.hir().krate_attrs(),
-            tcx.sess,
-            sym::type_length_limit,
-            2usize.pow(24),
-        ),
-    }
-}
-
-pub fn get_recursion_limit(krate_attrs: &[impl AttributeExt], sess: &Session) -> Limit {
-    get_limit(krate_attrs, sess, sym::recursion_limit, 128)
-}
-
-fn get_limit(
-    krate_attrs: &[impl AttributeExt],
-    sess: &Session,
-    name: Symbol,
-    default: usize,
-) -> Limit {
-    match get_limit_size(krate_attrs, sess, name) {
-        Some(size) => Limit::new(size),
-        None => Limit::new(default),
-    }
-}
-
-pub fn get_limit_size(
-    krate_attrs: &[impl AttributeExt],
-    sess: &Session,
-    name: Symbol,
-) -> Option<usize> {
-    for attr in krate_attrs {
-        if !attr.has_name(name) {
-            continue;
-        }
-
-        if let Some(sym) = attr.value_str() {
-            match sym.as_str().parse() {
-                Ok(n) => return Some(n),
-                Err(e) => {
-                    let error_str = match e.kind() {
-                        IntErrorKind::PosOverflow => "`limit` is too large",
-                        IntErrorKind::Empty => "`limit` must be a non-negative integer",
-                        IntErrorKind::InvalidDigit => "not a valid integer",
-                        IntErrorKind::NegOverflow => {
-                            bug!("`limit` should never negatively overflow")
-                        }
-                        IntErrorKind::Zero => bug!("zero is a valid `limit`"),
-                        kind => bug!("unimplemented IntErrorKind variant: {:?}", kind),
-                    };
-                    sess.dcx().emit_err(LimitInvalid {
-                        span: attr.span(),
-                        value_span: attr.value_span().unwrap(),
-                        error_str,
-                    });
-                }
-            }
-        }
-    }
-    None
-}

compiler/rustc_middle/src/middle/mod.rs

@@ -30,12 +30,7 @@ pub mod lib_features {
         }
     }
 }
-pub mod limits;
 pub mod privacy;
 pub mod region;
 pub mod resolve_bound_vars;
 pub mod stability;
-
-pub fn provide(providers: &mut crate::query::Providers) {
-    limits::provide(providers);
-}

compiler/rustc_middle/src/ty/context.rs

@@ -2168,6 +2168,10 @@ impl<'tcx> TyCtxt<'tcx> {
         self.limits(()).move_size_limit
     }
 
+    pub fn pattern_complexity_limit(self) -> Limit {
+        self.limits(()).pattern_complexity_limit
+    }
+
     /// All traits in the crate graph, including those not visible to the user.
     pub fn all_traits(self) -> impl Iterator<Item = DefId> + 'tcx {
         iter::once(LOCAL_CRATE)

compiler/rustc_middle/src/ty/mod.rs

@@ -2168,7 +2168,6 @@ pub fn provide(providers: &mut Providers) {
     util::provide(providers);
     print::provide(providers);
     super::util::bug::provide(providers);
-    super::middle::provide(providers);
     *providers = Providers {
         trait_impls_of: trait_def::trait_impls_of_provider,
         incoherent_impls: trait_def::incoherent_impls_provider,