Remove compare mode

src/bootstrap/flags.rs

@@ -304,7 +304,7 @@ pub enum Subcommand {
             ./x.py test library/std --test-args hash_map
             ./x.py test library/std --stage 0 --no-doc
             ./x.py test tests/ui --bless
-            ./x.py test tests/ui --compare-mode chalk
+            ./x.py test tests/ui --compare-mode next-solver
         Note that `test tests/* --stage N` does NOT depend on `build compiler/rustc --stage N`;
         just like `build library/std --stage N` it tests the compiler produced by the previous
         stage.

src/tools/compiletest/src/common.rs

@@ -107,7 +107,6 @@ string_enum! {
     #[derive(Clone, Debug, PartialEq)]
     pub enum CompareMode {
         Polonius => "polonius",
-        Chalk => "chalk",
         NextSolver => "next-solver",
         NextSolverCoherence => "next-solver-coherence",
         SplitDwarf => "split-dwarf",

src/tools/compiletest/src/runtest.rs

@@ -2435,9 +2435,6 @@ impl<'test> TestCx<'test> {
             Some(CompareMode::Polonius) => {
                 rustc.args(&["-Zpolonius"]);
             }
-            Some(CompareMode::Chalk) => {
-                rustc.args(&["-Ztrait-solver=chalk"]);
-            }
             Some(CompareMode::NextSolver) => {
                 rustc.args(&["-Ztrait-solver=next"]);
             }

src/tools/tidy/src/deps.rs

@@ -122,10 +122,6 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "byteorder", // via ruzstd in object in thorin-dwp
     "cc",
     "cfg-if",
-    "chalk-derive",
-    "chalk-engine",
-    "chalk-ir",
-    "chalk-solve",
     "compiler_builtins",
     "convert_case", // dependency of derive_more
     "cpufeatures",

tests/ui/feature-gates/feature-gate-type_alias_impl_trait.rs

@@ -1,4 +1,3 @@
-// ignore-compare-mode-chalk
 // check-pass
 #![feature(type_alias_impl_trait)]
 use std::fmt::Debug;

tests/ui/impl-trait/issue-55872-3.rs

@@ -1,5 +1,4 @@
 // edition:2018
-// ignore-compare-mode-chalk
 
 #![feature(impl_trait_in_assoc_type)]
 

tests/ui/impl-trait/issues/issue-65581.rs

@@ -1,5 +1,4 @@
 // check-pass
-// ignore-compare-mode-chalk
 
 #![allow(dead_code)]