Rollup merge of #119971 - compiler-errors:zip-eq, r=nnethercote

Use `zip_eq` to enforce that things being zipped have equal sizes

Some `zip`s are best enforced to be equal, since size mismatches suggest deeper bugs in the compiler.

Cargo.lock

@@ -3879,6 +3879,7 @@ dependencies = [
 name = "rustc_hir_analysis"
 version = "0.0.0"
 dependencies = [
+ "itertools",
  "rustc_arena",
  "rustc_ast",
  "rustc_attr",
@@ -3917,6 +3918,7 @@ dependencies = [
 name = "rustc_hir_typeck"
 version = "0.0.0"
 dependencies = [
+ "itertools",
  "rustc_ast",
  "rustc_attr",
  "rustc_data_structures",
@@ -4200,6 +4202,7 @@ name = "rustc_mir_build"
 version = "0.0.0"
 dependencies = [
  "either",
+ "itertools",
  "rustc_apfloat",
  "rustc_arena",
  "rustc_ast",

compiler/rustc_borrowck/src/type_check/input_output.rs

@@ -7,6 +7,7 @@
 //! `RETURN_PLACE` the MIR arguments) are always fully normalized (and
 //! contain revealed `impl Trait` values).
 
+use itertools::Itertools;
 use rustc_infer::infer::BoundRegionConversionTime;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty};
@@ -39,9 +40,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             user_provided_sig,
         );
 
-        for (&user_ty, arg_decl) in user_provided_sig.inputs().iter().zip(
-            // In MIR, closure args begin with an implicit `self`. Skip it!
-            body.args_iter().skip(1).map(|local| &body.local_decls[local]),
+        let is_coroutine_with_implicit_resume_ty = self.tcx().is_coroutine(mir_def_id.to_def_id())
+            && user_provided_sig.inputs().is_empty();
+
+        for (&user_ty, arg_decl) in user_provided_sig.inputs().iter().zip_eq(
+            // In MIR, closure args begin with an implicit `self`.
+            // Also, coroutines have a resume type which may be implicitly `()`.
+            body.args_iter()
+                .skip(1 + if is_coroutine_with_implicit_resume_ty { 1 } else { 0 })
+                .map(|local| &body.local_decls[local]),
         ) {
             self.ascribe_user_type_skip_wf(
                 arg_decl.ty,

compiler/rustc_hir_analysis/Cargo.toml

@@ -9,6 +9,7 @@ doctest = false
 
 [dependencies]
 # tidy-alphabetical-start
+itertools = "0.11"
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_attr = { path = "../rustc_attr" }

compiler/rustc_hir_analysis/src/variance/mod.rs

@@ -3,6 +3,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/variance.html
 
+use itertools::Itertools;
 use rustc_arena::DroplessArena;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -91,7 +92,7 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
         fn visit_opaque(&mut self, def_id: DefId, args: GenericArgsRef<'tcx>) -> ControlFlow<!> {
             if def_id != self.root_def_id && self.tcx.is_descendant_of(def_id, self.root_def_id) {
                 let child_variances = self.tcx.variances_of(def_id);
-                for (a, v) in args.iter().zip(child_variances) {
+                for (a, v) in args.iter().zip_eq(child_variances) {
                     if *v != ty::Bivariant {
                         a.visit_with(self)?;
                     }

compiler/rustc_hir_typeck/Cargo.toml

@@ -5,6 +5,7 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
+itertools = "0.11"
 rustc_ast = { path = "../rustc_ast" }
 rustc_attr = { path = "../rustc_attr" }
 rustc_data_structures = { path = "../rustc_data_structures" }

compiler/rustc_hir_typeck/src/autoderef.rs

@@ -2,6 +2,7 @@
 use super::method::MethodCallee;
 use super::{FnCtxt, PlaceOp};
 
+use itertools::Itertools;
 use rustc_hir_analysis::autoderef::{Autoderef, AutoderefKind};
 use rustc_infer::infer::InferOk;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
@@ -32,8 +33,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         autoderef: &Autoderef<'a, 'tcx>,
     ) -> InferOk<'tcx, Vec<Adjustment<'tcx>>> {
-        let mut obligations = vec![];
         let steps = autoderef.steps();
+        if steps.is_empty() {
+            return InferOk { obligations: vec![], value: vec![] };
+        }
+
+        let mut obligations = vec![];
         let targets =
             steps.iter().skip(1).map(|&(ty, _)| ty).chain(iter::once(autoderef.final_ty(false)));
         let steps: Vec<_> = steps
@@ -54,7 +59,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     None
                 }
             })
-            .zip(targets)
+            .zip_eq(targets)
             .map(|(autoderef, target)| Adjustment { kind: Adjust::Deref(autoderef), target })
             .collect();
 

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -9,6 +9,7 @@ use crate::{
     struct_span_code_err, BreakableCtxt, Diverges, Expectation, FnCtxt, Needs, RawTy,
     TupleArgumentsFlag,
 };
+use itertools::Itertools;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{
@@ -421,7 +422,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 formal_input_tys
                     .iter()
                     .copied()
-                    .zip(expected_input_tys.iter().copied())
+                    .zip_eq(expected_input_tys.iter().copied())
                     .map(|vars| self.resolve_vars_if_possible(vars)),
             );
 

compiler/rustc_mir_build/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 either = "1"
+itertools = "0.11"
 rustc_apfloat = "0.2.0"
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }

compiler/rustc_mir_build/src/build/mod.rs

@@ -1,5 +1,6 @@
 use crate::build::expr::as_place::PlaceBuilder;
 use crate::build::scope::DropKind;
+use itertools::Itertools;
 use rustc_apfloat::ieee::{Double, Single};
 use rustc_apfloat::Float;
 use rustc_ast::attr;
@@ -654,7 +655,7 @@ fn construct_error(tcx: TyCtxt<'_>, def_id: LocalDefId, guar: ErrorGuaranteed) -
                         ty::ClosureKind::FnOnce => closure_ty,
                     };
                     (
-                        [self_ty].into_iter().chain(sig.inputs().to_vec()).collect(),
+                        [self_ty].into_iter().chain(sig.inputs()[0].tuple_fields()).collect(),
                         sig.output(),
                         None,
                     )
@@ -835,7 +836,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.upvars = tcx
             .closure_captures(self.def_id)
             .iter()
-            .zip(capture_tys)
+            .zip_eq(capture_tys)
             .enumerate()
             .map(|(i, (captured_place, ty))| {
                 let name = captured_place.to_symbol();

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -2,6 +2,7 @@ use crate::errors;
 use crate::thir::cx::region::Scope;
 use crate::thir::cx::Cx;
 use crate::thir::util::UserAnnotatedTyHelpers;
+use itertools::Itertools;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
@@ -565,7 +566,7 @@ impl<'tcx> Cx<'tcx> {
                     .tcx
                     .closure_captures(def_id)
                     .iter()
-                    .zip(args.upvar_tys())
+                    .zip_eq(args.upvar_tys())
                     .map(|(captured_place, ty)| {
                         let upvars = self.capture_upvar(expr, captured_place, ty);
                         self.thir.exprs.push(upvars)

compiler/rustc_ty_utils/src/layout.rs

@@ -1052,6 +1052,8 @@ fn variant_info_for_coroutine<'tcx>(
     def_id: DefId,
     args: ty::GenericArgsRef<'tcx>,
 ) -> (Vec<VariantInfo>, Option<Size>) {
+    use itertools::Itertools;
+
     let Variants::Multiple { tag, ref tag_encoding, tag_field, .. } = layout.variants else {
         return (vec![], None);
     };
@@ -1064,7 +1066,7 @@ fn variant_info_for_coroutine<'tcx>(
         .as_coroutine()
         .upvar_tys()
         .iter()
-        .zip(upvar_names)
+        .zip_eq(upvar_names)
         .enumerate()
         .map(|(field_idx, (_, name))| {
             let field_layout = layout.field(cx, field_idx);