Rollup merge of rust-lang#77161 - est31:swich_len_already_trusted, r=petrochenkov

Remove TrustedLen requirement from BuilderMethods::switch

The main use case of TrustedLen is allowing APIs to specialize on it,
but no use of it uses that specialization. Instead, only the .len()
function provided by ExactSizeIterator is used, which is already
required to be accurate.

Thus, the TrustedLen requirement on BuilderMethods::switch is redundant.

Author: RalfJung

compiler/rustc_codegen_llvm/src/builder.rs

@@ -21,7 +21,6 @@ use rustc_target::abi::{self, Align, Size};
 use rustc_target::spec::{HasTargetSpec, Target};
 use std::borrow::Cow;
 use std::ffi::CStr;
-use std::iter::TrustedLen;
 use std::ops::{Deref, Range};
 use std::ptr;
 use tracing::debug;
@@ -179,7 +178,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         v: &'ll Value,
         else_llbb: &'ll BasicBlock,
-        cases: impl ExactSizeIterator<Item = (u128, &'ll BasicBlock)> + TrustedLen,
+        cases: impl ExactSizeIterator<Item = (u128, &'ll BasicBlock)>,
     ) {
         let switch =
             unsafe { llvm::LLVMBuildSwitch(self.llbuilder, v, else_llbb, cases.len() as c_uint) };

compiler/rustc_codegen_llvm/src/lib.rs

@@ -12,7 +12,6 @@
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![feature(or_patterns)]
-#![feature(trusted_len)]
 #![recursion_limit = "256"]
 
 use back::write::{create_informational_target_machine, create_target_machine};

compiler/rustc_codegen_ssa/src/lib.rs

@@ -6,7 +6,6 @@
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![feature(or_patterns)]
-#![feature(trusted_len)]
 #![feature(associated_type_bounds)]
 #![recursion_limit = "256"]
 

compiler/rustc_codegen_ssa/src/traits/builder.rs

@@ -18,7 +18,6 @@ use rustc_middle::ty::Ty;
 use rustc_target::abi::{Abi, Align, Scalar, Size};
 use rustc_target::spec::HasTargetSpec;
 
-use std::iter::TrustedLen;
 use std::ops::Range;
 
 #[derive(Copy, Clone)]
@@ -60,7 +59,7 @@ pub trait BuilderMethods<'a, 'tcx>:
         &mut self,
         v: Self::Value,
         else_llbb: Self::BasicBlock,
-        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock)> + TrustedLen,
+        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock)>,
     );
     fn invoke(
         &mut self,