Add [TRACKED_NO_CRATE_HASH] and [SUBSTRUCT] directives

This is necessary for options that should invalidate the incremental
hash but *not* affect the crate hash (e.g. --remap-path-prefix).

This doesn't add `for_crate_hash` to the trait directly because it's not
relevant for *types*, only for *options*, which are fields on a larger
struct. Instead, it adds a new `SUBSTRUCT` directive for options, which
does take a `for_crate_hash` parameter.

- Use TRACKED_NO_CRATE_HASH for --remap-path-prefix
- Add test that `remap_path_prefix` is tracked
- Reduce duplication in the test suite to avoid future churn

6 files changed, 133 insertions, 90 deletions

diff --git a/compiler/rustc_incremental/src/persist/load.rs b/compiler/rustc_incremental/src/persist/load.rs
index 259e540c612..2661afd7ffc 100644
--- a/compiler/rustc_incremental/src/persist/load.rs
+++ b/compiler/rustc_incremental/src/persist/load.rs
@@ -104,7 +104,7 @@ pub fn load_dep_graph(sess: &Session) -> DepGraphFuture {
     // Fortunately, we just checked that this isn't the case.
     let path = dep_graph_path_from(&sess.incr_comp_session_dir());
     let report_incremental_info = sess.opts.debugging_opts.incremental_info;
-    let expected_hash = sess.opts.dep_tracking_hash();
+    let expected_hash = sess.opts.dep_tracking_hash(false);
 
     let mut prev_work_products = FxHashMap::default();
     let nightly_build = sess.is_nightly_build();
diff --git a/compiler/rustc_incremental/src/persist/save.rs b/compiler/rustc_incremental/src/persist/save.rs
index d558af3c1d5..1484088837a 100644
--- a/compiler/rustc_incremental/src/persist/save.rs
+++ b/compiler/rustc_incremental/src/persist/save.rs
@@ -219,7 +219,7 @@ pub fn build_dep_graph(
     }
 
     // First encode the commandline arguments hash
-    if let Err(err) = sess.opts.dep_tracking_hash().encode(&mut encoder) {
+    if let Err(err) = sess.opts.dep_tracking_hash(false).encode(&mut encoder) {
         sess.err(&format!(
             "failed to write dependency graph hash `{}`: {}",
             path_buf.display(),
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 5800fa173dd..62c2d3c722f 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -19,6 +19,7 @@ use rustc_span::symbol::sym;
 use rustc_span::SourceFileHashAlgorithm;
 use rustc_target::spec::{CodeModel, LinkerFlavor, MergeFunctions, PanicStrategy};
 use rustc_target::spec::{RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo, TlsModel};
+
 use std::collections::{BTreeMap, BTreeSet};
 use std::iter::FromIterator;
 use std::num::NonZeroUsize;
@@ -74,6 +75,27 @@ fn mk_map<K: Ord, V>(entries: Vec<(K, V)>) -> BTreeMap<K, V> {
     BTreeMap::from_iter(entries.into_iter())
 }
 
+fn assert_same_clone(x: &Options) {
+    assert_eq!(x.dep_tracking_hash(true), x.clone().dep_tracking_hash(true));
+    assert_eq!(x.dep_tracking_hash(false), x.clone().dep_tracking_hash(false));
+}
+
+fn assert_same_hash(x: &Options, y: &Options) {
+    assert_eq!(x.dep_tracking_hash(true), y.dep_tracking_hash(true));
+    assert_eq!(x.dep_tracking_hash(false), y.dep_tracking_hash(false));
+    // Check clone
+    assert_same_clone(x);
+    assert_same_clone(y);
+}
+
+fn assert_different_hash(x: &Options, y: &Options) {
+    assert_ne!(x.dep_tracking_hash(true), y.dep_tracking_hash(true));
+    assert_ne!(x.dep_tracking_hash(false), y.dep_tracking_hash(false));
+    // Check clone
+    assert_same_clone(x);
+    assert_same_clone(y);
+}
+
 // When the user supplies --test we should implicitly supply --cfg test
 #[test]
 fn test_switch_implies_cfg_test() {
@@ -130,14 +152,9 @@ fn test_output_types_tracking_hash_different_paths() {
     v2.output_types = OutputTypes::new(&[(OutputType::Exe, Some(PathBuf::from("/some/thing")))]);
     v3.output_types = OutputTypes::new(&[(OutputType::Exe, None)]);
 
-    assert!(v1.dep_tracking_hash() != v2.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() != v3.dep_tracking_hash());
-    assert!(v2.dep_tracking_hash() != v3.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
+    assert_different_hash(&v1, &v2);
+    assert_different_hash(&v1, &v3);
+    assert_different_hash(&v2, &v3);
 }
 
 #[test]
@@ -155,10 +172,7 @@ fn test_output_types_tracking_hash_different_construction_order() {
         (OutputType::Exe, Some(PathBuf::from("./some/thing"))),
     ]);
 
-    assert_eq!(v1.dep_tracking_hash(), v2.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
+    assert_same_hash(&v1, &v2);
 }
 
 #[test]
@@ -182,14 +196,9 @@ fn test_externs_tracking_hash_different_construction_order() {
         (String::from("d"), new_public_extern_entry(vec!["f", "e"])),
     ]));
 
-    assert_eq!(v1.dep_tracking_hash(), v2.dep_tracking_hash());
-    assert_eq!(v1.dep_tracking_hash(), v3.dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v3.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
+    assert_same_hash(&v1, &v2);
+    assert_same_hash(&v1, &v3);
+    assert_same_hash(&v2, &v3);
 }
 
 #[test]
@@ -219,14 +228,9 @@ fn test_lints_tracking_hash_different_values() {
         (String::from("d"), Level::Deny),
     ];
 
-    assert!(v1.dep_tracking_hash() != v2.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() != v3.dep_tracking_hash());
-    assert!(v2.dep_tracking_hash() != v3.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
+    assert_different_hash(&v1, &v2);
+    assert_different_hash(&v1, &v3);
+    assert_different_hash(&v2, &v3);
 }
 
 #[test]
@@ -248,11 +252,7 @@ fn test_lints_tracking_hash_different_construction_order() {
         (String::from("d"), Level::Forbid),
     ];
 
-    assert_eq!(v1.dep_tracking_hash(), v2.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
+    assert_same_hash(&v1, &v2);
 }
 
 #[test]
@@ -292,15 +292,9 @@ fn test_search_paths_tracking_hash_different_order() {
     v4.search_paths.push(SearchPath::from_cli_opt("dependency=ghi", JSON));
     v4.search_paths.push(SearchPath::from_cli_opt("framework=jkl", JSON));
 
-    assert!(v1.dep_tracking_hash() == v2.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() == v3.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() == v4.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
-    assert_eq!(v4.dep_tracking_hash(), v4.clone().dep_tracking_hash());
+    assert_same_hash(&v1, &v2);
+    assert_same_hash(&v1, &v3);
+    assert_same_hash(&v1, &v4);
 }
 
 #[test]
@@ -338,15 +332,9 @@ fn test_native_libs_tracking_hash_different_values() {
         (String::from("c"), None, NativeLibKind::Unspecified),
     ];
 
-    assert!(v1.dep_tracking_hash() != v2.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() != v3.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() != v4.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
-    assert_eq!(v4.dep_tracking_hash(), v4.clone().dep_tracking_hash());
+    assert_different_hash(&v1, &v2);
+    assert_different_hash(&v1, &v3);
+    assert_different_hash(&v1, &v4);
 }
 
 #[test]
@@ -374,14 +362,9 @@ fn test_native_libs_tracking_hash_different_order() {
         (String::from("b"), None, NativeLibKind::Framework),
     ];
 
-    assert!(v1.dep_tracking_hash() == v2.dep_tracking_hash());
-    assert!(v1.dep_tracking_hash() == v3.dep_tracking_hash());
-    assert!(v2.dep_tracking_hash() == v3.dep_tracking_hash());
-
-    // Check clone
-    assert_eq!(v1.dep_tracking_hash(), v1.clone().dep_tracking_hash());
-    assert_eq!(v2.dep_tracking_hash(), v2.clone().dep_tracking_hash());
-    assert_eq!(v3.dep_tracking_hash(), v3.clone().dep_tracking_hash());
+    assert_same_hash(&v1, &v2);
+    assert_same_hash(&v1, &v3);
+    assert_same_hash(&v2, &v3);
 }
 
 #[test]
@@ -393,7 +376,7 @@ fn test_codegen_options_tracking_hash() {
         ($name: ident, $non_default_value: expr) => {
             assert_ne!(opts.cg.$name, $non_default_value);
             opts.cg.$name = $non_default_value;
-            assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
+            assert_same_hash(&reference, &opts);
         };
     }
 
@@ -419,7 +402,7 @@ fn test_codegen_options_tracking_hash() {
             opts = reference.clone();
             assert_ne!(opts.cg.$name, $non_default_value);
             opts.cg.$name = $non_default_value;
-            assert_ne!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
+            assert_different_hash(&reference, &opts);
         };
     }
 
@@ -457,6 +440,28 @@ fn test_codegen_options_tracking_hash() {
 }
 
 #[test]
+fn test_top_level_options_tracked_no_crate() {
+    let reference = Options::default();
+    let mut opts;
+
+    macro_rules! tracked {
+        ($name: ident, $non_default_value: expr) => {
+            opts = reference.clone();
+            assert_ne!(opts.$name, $non_default_value);
+            opts.$name = $non_default_value;
+            // The crate hash should be the same
+            assert_eq!(reference.dep_tracking_hash(true), opts.dep_tracking_hash(true));
+            // The incremental hash should be different
+            assert_ne!(reference.dep_tracking_hash(false), opts.dep_tracking_hash(false));
+        };
+    }
+
+    // Make sure that changing a [TRACKED_NO_CRATE_HASH] option leaves the crate hash unchanged but changes the incremental hash.
+    // This list is in alphabetical order.
+    tracked!(remap_path_prefix, vec![("/home/bors/rust".into(), "src".into())]);
+}
+
+#[test]
 fn test_debugging_options_tracking_hash() {
     let reference = Options::default();
     let mut opts = Options::default();
@@ -465,7 +470,7 @@ fn test_debugging_options_tracking_hash() {
         ($name: ident, $non_default_value: expr) => {
             assert_ne!(opts.debugging_opts.$name, $non_default_value);
             opts.debugging_opts.$name = $non_default_value;
-            assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
+            assert_same_hash(&reference, &opts);
         };
     }
 
@@ -537,7 +542,7 @@ fn test_debugging_options_tracking_hash() {
             opts = reference.clone();
             assert_ne!(opts.debugging_opts.$name, $non_default_value);
             opts.debugging_opts.$name = $non_default_value;
-            assert_ne!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
+            assert_different_hash(&reference, &opts);
         };
     }
 
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index d155276051e..4cd126988f9 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -943,7 +943,7 @@ pub(super) fn index_hir<'tcx>(tcx: TyCtxt<'tcx>, cnum: CrateNum) -> &'tcx Indexe
         intravisit::walk_crate(&mut collector, tcx.untracked_crate);
 
         let crate_disambiguator = tcx.sess.local_crate_disambiguator();
-        let cmdline_args = tcx.sess.opts.dep_tracking_hash();
+        let cmdline_args = tcx.sess.opts.dep_tracking_hash(true);
         collector.finalize_and_compute_crate_hash(crate_disambiguator, &*tcx.cstore, cmdline_args)
     };
 
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index a7b9d03844c..5d588ad1be2 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -2374,6 +2374,7 @@ crate mod dep_tracking {
 
     impl_dep_tracking_hash_for_sortable_vec_of!(String);
     impl_dep_tracking_hash_for_sortable_vec_of!(PathBuf);
+    impl_dep_tracking_hash_for_sortable_vec_of!((PathBuf, PathBuf));
     impl_dep_tracking_hash_for_sortable_vec_of!(CrateType);
     impl_dep_tracking_hash_for_sortable_vec_of!((String, lint::Level));
     impl_dep_tracking_hash_for_sortable_vec_of!((String, Option<String>, NativeLibKind));
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 759110f6859..226c7bda052 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -20,21 +20,41 @@ use std::num::NonZeroUsize;
 use std::path::PathBuf;
 use std::str;
 
-macro_rules! hash_option {
-    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, [UNTRACKED]) => {{}};
-    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, [TRACKED]) => {{
+macro_rules! insert {
+    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr) => {
         if $sub_hashes
             .insert(stringify!($opt_name), $opt_expr as &dyn dep_tracking::DepTrackingHash)
             .is_some()
         {
             panic!("duplicate key in CLI DepTrackingHash: {}", stringify!($opt_name))
         }
+    };
+}
+
+macro_rules! hash_opt {
+    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, $_for_crate_hash: ident, [UNTRACKED]) => {{}};
+    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, $_for_crate_hash: ident, [TRACKED]) => {{ insert!($opt_name, $opt_expr, $sub_hashes) }};
+    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, $for_crate_hash: ident, [TRACKED_NO_CRATE_HASH]) => {{
+        if !$for_crate_hash {
+            insert!($opt_name, $opt_expr, $sub_hashes)
+        }
     }};
+    ($opt_name:ident, $opt_expr:expr, $sub_hashes:expr, $_for_crate_hash: ident, [SUBSTRUCT]) => {{}};
+}
+
+macro_rules! hash_substruct {
+    ($opt_name:ident, $opt_expr:expr, $error_format:expr, $for_crate_hash:expr, $hasher:expr, [UNTRACKED]) => {{}};
+    ($opt_name:ident, $opt_expr:expr, $error_format:expr, $for_crate_hash:expr, $hasher:expr, [TRACKED]) => {{}};
+    ($opt_name:ident, $opt_expr:expr, $error_format:expr, $for_crate_hash:expr, $hasher:expr, [TRACKED_NO_CRATE_HASH]) => {{}};
+    ($opt_name:ident, $opt_expr:expr, $error_format:expr, $for_crate_hash:expr, $hasher:expr, [SUBSTRUCT]) => {
+        use crate::config::dep_tracking::DepTrackingHash;
+        $opt_expr.dep_tracking_hash($for_crate_hash, $error_format).hash($hasher, $error_format);
+    };
 }
 
 macro_rules! top_level_options {
     (pub struct Options { $(
-        $opt:ident : $t:ty [$dep_tracking_marker:ident $($warn_val:expr, $warn_text:expr)*],
+        $opt:ident : $t:ty [$dep_tracking_marker:ident],
     )* } ) => (
         #[derive(Clone)]
         pub struct Options {
@@ -42,20 +62,27 @@ macro_rules! top_level_options {
         }
 
         impl Options {
-            pub fn dep_tracking_hash(&self) -> u64 {
+            pub fn dep_tracking_hash(&self, for_crate_hash: bool) -> u64 {
                 let mut sub_hashes = BTreeMap::new();
                 $({
-                    hash_option!($opt,
-                                 &self.$opt,
-                                 &mut sub_hashes,
-                                 [$dep_tracking_marker $($warn_val,
-                                                         $warn_text,
-                                                         self.error_format)*]);
+                    hash_opt!($opt,
+                                &self.$opt,
+                                &mut sub_hashes,
+                                for_crate_hash,
+                                [$dep_tracking_marker]);
                 })*
                 let mut hasher = DefaultHasher::new();
                 dep_tracking::stable_hash(sub_hashes,
                                           &mut hasher,
                                           self.error_format);
+                $({
+                    hash_substruct!($opt,
+                        &self.$opt,
+                        self.error_format,
+                        for_crate_hash,
+                        &mut hasher,
+                        [$dep_tracking_marker]);
+                })*
                 hasher.finish()
             }
         }
@@ -72,9 +99,16 @@ macro_rules! top_level_options {
 // A change in the given field will cause the compiler to completely clear the
 // incremental compilation cache before proceeding.
 //
+// [TRACKED_NO_CRATE_HASH]
+// Same as [TRACKED], but will not affect the crate hash. This is useful for options that only
+// affect the incremental cache.
+//
 // [UNTRACKED]
 // Incremental compilation is not influenced by this option.
 //
+// [SUBSTRUCT]
+// Second-level sub-structs containing more options.
+//
 // If you add a new option to this struct or one of the sub-structs like
 // `CodegenOptions`, think about how it influences incremental compilation. If in
 // doubt, specify [TRACKED], which is always "correct" but might lead to
@@ -106,12 +140,12 @@ top_level_options!(
         // directory to store intermediate results.
         incremental: Option<PathBuf> [UNTRACKED],
 
-        debugging_opts: DebuggingOptions [TRACKED],
+        debugging_opts: DebuggingOptions [SUBSTRUCT],
         prints: Vec<PrintRequest> [UNTRACKED],
         // Determines which borrow checker(s) to run. This is the parsed, sanitized
         // version of `debugging_opts.borrowck`, which is just a plain string.
         borrowck_mode: BorrowckMode [UNTRACKED],
-        cg: CodegenOptions [TRACKED],
+        cg: CodegenOptions [SUBSTRUCT],
         externs: Externs [UNTRACKED],
         extern_dep_specs: ExternDepSpecs [UNTRACKED],
         crate_name: Option<String> [TRACKED],
@@ -139,7 +173,7 @@ top_level_options!(
         cli_forced_thinlto_off: bool [UNTRACKED],
 
         // Remap source path prefixes in all output (messages, object files, debug, etc.).
-        remap_path_prefix: Vec<(PathBuf, PathBuf)> [UNTRACKED],
+        remap_path_prefix: Vec<(PathBuf, PathBuf)> [TRACKED_NO_CRATE_HASH],
 
         edition: Edition [TRACKED],
 
@@ -169,7 +203,7 @@ macro_rules! options {
      $($opt:ident : $t:ty = (
         $init:expr,
         $parse:ident,
-        [$dep_tracking_marker:ident $(($dep_warn_val:expr, $dep_warn_text:expr))*],
+        [$dep_tracking_marker:ident],
         $desc:expr)
      ),* ,) =>
 (
@@ -219,18 +253,21 @@ macro_rules! options {
         return op;
     }
 
-    impl dep_tracking::DepTrackingHash for $struct_name {
-        fn hash(&self, hasher: &mut DefaultHasher, error_format: ErrorOutputType) {
+    impl $struct_name {
+        fn dep_tracking_hash(&self, for_crate_hash: bool, error_format: ErrorOutputType) -> u64 {
             let mut sub_hashes = BTreeMap::new();
             $({
-                hash_option!($opt,
-                             &self.$opt,
-                             &mut sub_hashes,
-                             [$dep_tracking_marker $($dep_warn_val,
-                                                     $dep_warn_text,
-                                                     error_format)*]);
+                hash_opt!($opt,
+                            &self.$opt,
+                            &mut sub_hashes,
+                            for_crate_hash,
+                            [$dep_tracking_marker]);
             })*
-            dep_tracking::stable_hash(sub_hashes, hasher, error_format);
+            let mut hasher = DefaultHasher::new();
+            dep_tracking::stable_hash(sub_hashes,
+                                        &mut hasher,
+                                        error_format);
+            hasher.finish()
         }
     }