Rollup merge of #146254 - yotamofek:pr/itertools-all-equal-value, r=cjgillot

Use `Itertools::all_equal_value()` where applicable
Just a small cleanup.
We already have `itertools` as a dep in these crates, so might as well use another of its features.
Makes the code simpler IMHO :)

Author: matthiaskrgr

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -1,3 +1,4 @@
+use itertools::Itertoolsas _;
 use rustc_abi::{selfas abi,FIRST_VARIANT};
 use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::layout::{HasTyCtxt,HasTypingEnv,LayoutOf,TyAndLayout};
@@ -111,14 +112,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 let size = bx.const_usize(dest.layout.size.bytes());
 
 // Use llvm.memset.p0i8.* to initialize all same byte arrays
-ifletSome(int) = bx.cx().const_to_opt_u128(v,false){
-let bytes = &int.to_le_bytes()[..cg_elem.layout.size.bytes_usize()];
-let first = bytes[0];
-if bytes[1..].iter().all(|&b| b == first){
-let fill = bx.cx().const_u8(first);
- bx.memset(start, fill, size, dest.val.align,MemFlags::empty());
-returntrue;
-}
+ifletSome(int) = bx.cx().const_to_opt_u128(v,false)
+ && let bytes = &int.to_le_bytes()[..cg_elem.layout.size.bytes_usize()]
+ && letOk(&byte) = bytes.iter().all_equal_value()
+{
+let fill = bx.cx().const_u8(byte);
+ bx.memset(start, fill, size, dest.val.align,MemFlags::empty());
+returntrue;
 }
 
 // Use llvm.memset.p0i8.* to initialize byte arrays
@@ -130,13 +130,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 false
 };
 
-match cg_elem.val{
-OperandValue::Immediate(v) => {
-iftry_init_all_same(bx, v){
-return;
-}
-}
- _ => (),
+ifletOperandValue::Immediate(v) = cg_elem.val
+ && try_init_all_same(bx, v)
+{
+return;
 }
 
 let count = self

compiler/rustc_mir_transform/src/gvn.rs

@@ -87,6 +87,7 @@
 use std::borrow::Cow;
 
 use either::Either;
+use itertools::Itertoolsas _;
 use rustc_abi::{selfas abi,BackendRepr,FIRST_VARIANT,FieldIdx,Primitive,Size,VariantIdx};
 use rustc_const_eval::const_eval::DummyMachine;
 use rustc_const_eval::interpret::{
@@ -1023,15 +1024,15 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
 }
 };
 
-if ty.is_array() && fields.len() > 4{
-let first = fields[0];
-if fields.iter().all(|&v| v == first){
-let len = ty::Const::from_target_usize(self.tcx, fields.len().try_into().unwrap());
-ifletSome(op) = self.try_as_operand(first, location){
-*rvalue = Rvalue::Repeat(op, len);
-}
-returnSome(self.insert(ty,Value::Repeat(first, len)));
+if ty.is_array()
+ && fields.len() > 4
+ && letOk(&first) = fields.iter().all_equal_value()
+{
+let len = ty::Const::from_target_usize(self.tcx, fields.len().try_into().unwrap());
+ifletSome(op) = self.try_as_operand(first, location){
+*rvalue = Rvalue::Repeat(op, len);
 }
+returnSome(self.insert(ty,Value::Repeat(first, len)));
 }
 
 ifletSome(value) =

compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs

@@ -2,6 +2,7 @@ use std::cell::RefCell;
 use std::collections::hash_map;
 use std::rc::Rc;
 
+use itertools::Itertoolsas _;
 use rustc_data_structures::fx::{FxHashMap,FxHashSet,FxIndexMap};
 use rustc_data_structures::unord::{UnordMap,UnordSet};
 use rustc_errors::Subdiagnostic;
@@ -339,9 +340,9 @@ pub(crate) fn run_lint<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId, body: &Body<
 // Suppose that all BIDs point into the same local,
 // we can remove the this local from the observed drops,
 // so that we can focus our diagnosis more on the others.
-if candidates.iter().all(|&(_, place)| candidates[0].1.local == place.local){
+ifletOk(local) = candidates.iter().map(|&(_, place)| place.local).all_equal_value(){
 for path_idx in all_locals_dropped.iter(){
-if move_data.move_paths[path_idx].place.local == candidates[0].1.local{
+if move_data.move_paths[path_idx].place.local == local {
  to_exclude.insert(path_idx);
 }
 }

compiler/rustc_mir_transform/src/simplify.rs

@@ -34,6 +34,7 @@
 //! The normal logic that a program with UB can be changed to do anything does not apply to
 //! pre-"runtime" MIR!
 
+use itertools::Itertoolsas _;
 use rustc_index::{Idx,IndexSlice,IndexVec};
 use rustc_middle::mir::visit::{MutVisitor,MutatingUseContext,PlaceContext,Visitor};
 use rustc_middle::mir::*;
@@ -288,20 +289,13 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
 returnfalse;
 };
 
-let first_succ = {
-ifletSome(first_succ) = terminator.successors().next(){
-if terminator.successors().all(|s| s == first_succ){
-let count = terminator.successors().count();
-self.pred_count[first_succ] -= (count - 1)asu32;
- first_succ
-}else{
-returnfalse;
-}
-}else{
-returnfalse;
-}
+letOk(first_succ) = terminator.successors().all_equal_value()else{
+returnfalse;
 };
 
+let count = terminator.successors().count();
+self.pred_count[first_succ] -= (count - 1)asu32;
+
 debug!("simplifying branch {:?}", terminator);
  terminator.kind = TerminatorKind::Goto{target: first_succ };
 true

compiler/rustc_resolve/src/diagnostics.rs

@@ -1,3 +1,4 @@
+use itertools::Itertoolsas _;
 use rustc_ast::visit::{self,Visitor};
 use rustc_ast::{
 selfas ast,CRATE_NODE_ID,Crate,ItemKind,ModKind,NodeId,Path, join_path_idents,
@@ -3469,16 +3470,11 @@ fn show_candidates(
  err.note(note.to_string());
 }
 }else{
-let(_, descr_first, _, _, _) = &inaccessible_path_strings[0];
-let descr = if inaccessible_path_strings
+let descr = inaccessible_path_strings
 .iter()
-.skip(1)
-.all(|(_, descr, _, _, _)| descr == descr_first)
-{
- descr_first
-}else{
-"item"
-};
+.map(|&(_, descr, _, _, _)| descr)
+.all_equal_value()
+.unwrap_or("item");
 let plural_descr =
 if descr.ends_with('s'){format!("{descr}es")}else{format!("{descr}s")};