Auto merge of #111641 - michaelwoerister:debugger-visualizer-fixes, r=cjgillot

Fix dependency tracking for debugger visualizers

This PR fixes dependency tracking for debugger visualizer files by changing the `debugger_visualizers` query to an `eval_always` query that scans the AST while it is still available. This way the set of visualizer files is already available when dep-info is emitted. Since the query is turned into an `eval_always` query, dependency tracking will now reliably detect changes to the visualizer script files themselves.

TODO:
 - [x] perf.rlo
 - [x] Needs a bit more documentation in some places
 - [x] Needs regression test for the incr. comp. case

Fixes #111226
Fixes #111227
Fixes #111295

r? `@wesleywiser`
cc `@gibbyfree`

Author: bors

compiler/rustc_ast_lowering/src/lib.rs

@@ -58,7 +58,7 @@ use rustc_errors::{
 use rustc_fluent_macro::fluent_messages;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
-use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
+use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
 use rustc_hir::definitions::DefPathData;
 use rustc_hir::{ConstArg, GenericArg, ItemLocalId, ParamName, TraitCandidate};
 use rustc_index::{Idx, IndexSlice, IndexVec};
@@ -435,6 +435,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     // Queries that borrow `resolver_for_lowering`.
     tcx.ensure_with_value().output_filenames(());
     tcx.ensure_with_value().early_lint_checks(());
+    tcx.ensure_with_value().debugger_visualizers(LOCAL_CRATE);
     let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
 
     let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);

compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs

@@ -9,10 +9,9 @@ use rustc_ast::attr;
 use rustc_codegen_ssa::base::collect_debugger_visualizers_transitive;
 use rustc_codegen_ssa::traits::*;
 use rustc_hir::def_id::LOCAL_CRATE;
-use rustc_middle::bug;
+use rustc_middle::{bug, middle::debugger_visualizer::DebuggerVisualizerType};
 use rustc_session::config::{CrateType, DebugInfo};
 use rustc_span::symbol::sym;
-use rustc_span::DebuggerVisualizerType;
 
 /// Inserts a side-effect free instruction sequence that makes sure that the
 /// .debug_gdb_scripts global is referenced, so it isn't removed by the linker.

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -9,6 +9,7 @@ use rustc_fs_util::fix_windows_verbatim_for_gcc;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_metadata::find_native_static_library;
 use rustc_metadata::fs::{emit_wrapper_file, METADATA_FILENAME};
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
 use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, LdImpl, Strip};
@@ -21,7 +22,6 @@ use rustc_session::utils::NativeLibKind;
 /// need out of the shared crate context before we get rid of it.
 use rustc_session::{filesearch, Session};
 use rustc_span::symbol::Symbol;
-use rustc_span::DebuggerVisualizerFile;
 use rustc_target::spec::crt_objects::{CrtObjects, LinkSelfContainedDefault};
 use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, LinkerFlavorCli, Lld, PanicStrategy};
 use rustc_target::spec::{RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo};

compiler/rustc_codegen_ssa/src/base.rs

@@ -23,6 +23,7 @@ use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::lang_items::LangItem;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc_middle::middle::debugger_visualizer::{DebuggerVisualizerFile, DebuggerVisualizerType};
 use rustc_middle::middle::exported_symbols;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
 use rustc_middle::middle::lang_items;
@@ -35,7 +36,6 @@ use rustc_session::config::{self, CrateType, EntryFnType, OutputType};
 use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::Symbol;
-use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType};
 use rustc_target::abi::{Align, FIRST_VARIANT};
 
 use std::collections::BTreeSet;

compiler/rustc_codegen_ssa/src/lib.rs

@@ -28,6 +28,7 @@ use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
 use rustc_fluent_macro::fluent_messages;
 use rustc_hir::def_id::CrateNum;
 use rustc_middle::dep_graph::WorkProduct;
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Dependencies;
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
 use rustc_middle::query::{ExternProviders, Providers};
@@ -38,7 +39,6 @@ use rustc_session::cstore::{self, CrateSource};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::Session;
 use rustc_span::symbol::Symbol;
-use rustc_span::DebuggerVisualizerFile;
 use std::collections::BTreeSet;
 use std::io;
 use std::path::{Path, PathBuf};

compiler/rustc_interface/src/passes.rs

@@ -487,6 +487,11 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
             files.push(normalize_path(profile_sample.as_path().to_path_buf()));
         }
 
+        // Debugger visualizer files
+        for debugger_visualizer in tcx.debugger_visualizers(LOCAL_CRATE) {
+            files.push(normalize_path(debugger_visualizer.path.clone().unwrap()));
+        }
+
         if sess.binary_dep_depinfo() {
             if let Some(ref backend) = sess.opts.unstable_opts.codegen_backend {
                 if backend.contains('.') {

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -19,6 +19,7 @@ use rustc_hir::definitions::{DefKey, DefPath, DefPathData, DefPathHash};
 use rustc_hir::diagnostic_items::DiagnosticItems;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::metadata::ModChild;
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc_middle::ty::codec::TyDecoder;
@@ -958,7 +959,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             .decode((self, sess))
     }
 
-    fn get_debugger_visualizers(self) -> Vec<rustc_span::DebuggerVisualizerFile> {
+    fn get_debugger_visualizers(self) -> Vec<DebuggerVisualizerFile> {
         self.root.debugger_visualizers.decode(self).collect::<Vec<_>>()
     }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -19,6 +19,7 @@ use rustc_hir::definitions::DefPathData;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::lang_items::LangItem;
 use rustc_middle::hir::nested_filter;
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::{
     metadata_symbol_name, ExportedSymbol, SymbolExportInfo,
@@ -36,9 +37,7 @@ use rustc_session::config::{CrateType, OptLevel};
 use rustc_session::cstore::{ForeignModule, LinkagePreference, NativeLib};
 use rustc_span::hygiene::{ExpnIndex, HygieneEncodeContext, MacroKind};
 use rustc_span::symbol::{sym, Symbol};
-use rustc_span::{
-    self, DebuggerVisualizerFile, ExternalSource, FileName, SourceFile, Span, SyntaxContext,
-};
+use rustc_span::{self, ExternalSource, FileName, SourceFile, Span, SyntaxContext};
 use std::borrow::Borrow;
 use std::collections::hash_map::Entry;
 use std::hash::Hash;
@@ -1855,7 +1854,16 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
 
     fn encode_debugger_visualizers(&mut self) -> LazyArray<DebuggerVisualizerFile> {
         empty_proc_macro!(self);
-        self.lazy_array(self.tcx.debugger_visualizers(LOCAL_CRATE).iter())
+        self.lazy_array(
+            self.tcx
+                .debugger_visualizers(LOCAL_CRATE)
+                .iter()
+                // Erase the path since it may contain privacy sensitive data
+                // that we don't want to end up in crate metadata.
+                // The path is only needed for the local crate because of
+                // `--emit dep-info`.
+                .map(DebuggerVisualizerFile::path_erased),
+        )
     }
 
     fn encode_crate_deps(&mut self) -> LazyArray<CrateDep> {

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -2,6 +2,7 @@ use crate::creader::CrateMetadataRef;
 use decoder::Metadata;
 use def_path_hash_map::DefPathHashMapRef;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use table::TableBuilder;
 
 use rustc_ast as ast;
@@ -245,7 +246,7 @@ pub(crate) struct CrateRoot {
     proc_macro_data: Option<ProcMacroData>,
 
     tables: LazyTables,
-    debugger_visualizers: LazyArray<rustc_span::DebuggerVisualizerFile>,
+    debugger_visualizers: LazyArray<DebuggerVisualizerFile>,
 
     exported_symbols: LazyArray<(ExportedSymbol<'static>, SymbolExportInfo)>,
 

compiler/rustc_middle/src/hir/map/mod.rs

@@ -1,4 +1,5 @@
 use crate::hir::{ModuleItems, Owner};
+use crate::middle::debugger_visualizer::DebuggerVisualizerFile;
 use crate::query::LocalCrate;
 use crate::ty::TyCtxt;
 use rustc_ast as ast;
@@ -1165,11 +1166,26 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, _: LocalCrate) -> Svh {
 
     source_file_names.sort_unstable();
 
+    // We have to take care of debugger visualizers explicitly. The HIR (and
+    // thus `hir_body_hash`) contains the #[debugger_visualizer] attributes but
+    // these attributes only store the file path to the visualizer file, not
+    // their content. Yet that content is exported into crate metadata, so any
+    // changes to it need to be reflected in the crate hash.
+    let debugger_visualizers: Vec<_> = tcx
+        .debugger_visualizers(LOCAL_CRATE)
+        .iter()
+        // We ignore the path to the visualizer file since it's not going to be
+        // encoded in crate metadata and we already hash the full contents of
+        // the file.
+        .map(DebuggerVisualizerFile::path_erased)
+        .collect();
+
     let crate_hash: Fingerprint = tcx.with_stable_hashing_context(|mut hcx| {
         let mut stable_hasher = StableHasher::new();
         hir_body_hash.hash_stable(&mut hcx, &mut stable_hasher);
         upstream_crates.hash_stable(&mut hcx, &mut stable_hasher);
         source_file_names.hash_stable(&mut hcx, &mut stable_hasher);
+        debugger_visualizers.hash_stable(&mut hcx, &mut stable_hasher);
         if tcx.sess.opts.incremental_relative_spans() {
             let definitions = tcx.definitions_untracked();
             let mut owner_spans: Vec<_> = krate

compiler/rustc_middle/src/middle/debugger_visualizer.rs

@@ -0,0 +1,38 @@
+use rustc_data_structures::sync::Lrc;
+use std::path::PathBuf;
+
+#[derive(HashStable)]
+#[derive(Copy, PartialEq, PartialOrd, Clone, Ord, Eq, Hash, Debug, Encodable, Decodable)]
+pub enum DebuggerVisualizerType {
+    Natvis,
+    GdbPrettyPrinter,
+}
+
+/// A single debugger visualizer file.
+#[derive(HashStable)]
+#[derive(Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Encodable, Decodable)]
+pub struct DebuggerVisualizerFile {
+    /// The complete debugger visualizer source.
+    pub src: Lrc<[u8]>,
+    /// Indicates which visualizer type this targets.
+    pub visualizer_type: DebuggerVisualizerType,
+    /// The file path to the visualizer file. This is used for reporting
+    /// visualizer files in dep-info. Before it is written to crate metadata,
+    /// the path is erased to `None`, so as not to emit potentially privacy
+    /// sensitive data.
+    pub path: Option<PathBuf>,
+}
+
+impl DebuggerVisualizerFile {
+    pub fn new(src: Lrc<[u8]>, visualizer_type: DebuggerVisualizerType, path: PathBuf) -> Self {
+        DebuggerVisualizerFile { src, visualizer_type, path: Some(path) }
+    }
+
+    pub fn path_erased(&self) -> Self {
+        DebuggerVisualizerFile {
+            src: self.src.clone(),
+            visualizer_type: self.visualizer_type,
+            path: None,
+        }
+    }
+}

compiler/rustc_middle/src/middle/mod.rs

@@ -1,4 +1,5 @@
 pub mod codegen_fn_attrs;
+pub mod debugger_visualizer;
 pub mod dependency_format;
 pub mod exported_symbols;
 pub mod lang_items;

compiler/rustc_middle/src/query/mod.rs

@@ -12,6 +12,7 @@ use crate::infer::canonical::{self, Canonical};
 use crate::lint::LintExpectation;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
+use crate::middle::debugger_visualizer::DebuggerVisualizerFile;
 use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use crate::middle::lib_features::LibFeatures;
 use crate::middle::privacy::EffectiveVisibilities;
@@ -1784,12 +1785,18 @@ rustc_queries! {
         desc { "looking at the source for a crate" }
         separate_provide_extern
     }
+
     /// Returns the debugger visualizers defined for this crate.
-    query debugger_visualizers(_: CrateNum) -> &'tcx Vec<rustc_span::DebuggerVisualizerFile> {
+    /// NOTE: This query has to be marked `eval_always` because it reads data
+    ///       directly from disk that is not tracked anywhere else. I.e. it
+    ///       represents a genuine input to the query system.
+    query debugger_visualizers(_: CrateNum) -> &'tcx Vec<DebuggerVisualizerFile> {
         arena_cache
         desc { "looking up the debugger visualizers for this crate" }
         separate_provide_extern
+        eval_always
     }
+
     query postorder_cnums(_: ()) -> &'tcx [CrateNum] {
         eval_always
         desc { "generating a postorder list of CrateNums" }

compiler/rustc_middle/src/ty/parameterized.rs

@@ -56,6 +56,7 @@ trivially_parameterized_over_tcx! {
     std::string::String,
     crate::metadata::ModChild,
     crate::middle::codegen_fn_attrs::CodegenFnAttrs,
+    crate::middle::debugger_visualizer::DebuggerVisualizerFile,
     crate::middle::exported_symbols::SymbolExportInfo,
     crate::middle::resolve_bound_vars::ObjectLifetimeDefault,
     crate::mir::ConstQualifs,
@@ -91,7 +92,6 @@ trivially_parameterized_over_tcx! {
     rustc_session::cstore::ForeignModule,
     rustc_session::cstore::LinkagePreference,
     rustc_session::cstore::NativeLib,
-    rustc_span::DebuggerVisualizerFile,
     rustc_span::ExpnData,
     rustc_span::ExpnHash,
     rustc_span::ExpnId,

compiler/rustc_passes/src/check_attr.rs

@@ -8,7 +8,6 @@ use crate::{errors, fluent_generated as fluent};
 use rustc_ast::{ast, AttrStyle, Attribute, LitKind, MetaItemKind, MetaItemLit, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{Applicability, IntoDiagnosticArg, MultiSpan};
-use rustc_expand::base::resolve_path;
 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
@@ -1916,6 +1915,10 @@ impl CheckAttrVisitor<'_> {
 
     /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
     fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
+        // Here we only check that the #[debugger_visualizer] attribute is attached
+        // to nothing other than a module. All other checks are done in the
+        // `debugger_visualizer` query where they need to be done for decoding
+        // anyway.
         match target {
             Target::Mod => {}
             _ => {
@@ -1924,53 +1927,7 @@ impl CheckAttrVisitor<'_> {
             }
         }
 
-        let Some(hints) = attr.meta_item_list() else {
-            self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
-            return false;
-        };
-
-        let hint = match hints.len() {
-            1 => &hints[0],
-            _ => {
-                self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
-                return false;
-            }
-        };
-
-        let Some(meta_item) = hint.meta_item() else {
-            self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
-            return false;
-        };
-
-        let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
-            (sym::natvis_file, Some(value)) => value,
-            (sym::gdb_script_file, Some(value)) => value,
-            (_, _) => {
-                self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
-                return false;
-            }
-        };
-
-        let file =
-            match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
-                Ok(file) => file,
-                Err(mut err) => {
-                    err.emit();
-                    return false;
-                }
-            };
-
-        match std::fs::File::open(&file) {
-            Ok(_) => true,
-            Err(error) => {
-                self.tcx.sess.emit_err(errors::DebugVisualizerUnreadable {
-                    span: meta_item.span,
-                    file: &file,
-                    error,
-                });
-                false
-            }
-        }
+        true
     }
 
     /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.

compiler/rustc_passes/src/debugger_visualizer.rs

@@ -1,60 +1,69 @@
 //! Detecting usage of the `#[debugger_visualizer]` attribute.
 
-use hir::CRATE_HIR_ID;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_ast::Attribute;
 use rustc_data_structures::sync::Lrc;
 use rustc_expand::base::resolve_path;
-use rustc_hir as hir;
-use rustc_hir::HirId;
-use rustc_middle::query::{LocalCrate, Providers};
-use rustc_middle::ty::TyCtxt;
-use rustc_span::{sym, DebuggerVisualizerFile, DebuggerVisualizerType};
+use rustc_middle::{
+    middle::debugger_visualizer::{DebuggerVisualizerFile, DebuggerVisualizerType},
+    query::{LocalCrate, Providers},
+    ty::TyCtxt,
+};
+use rustc_session::Session;
+use rustc_span::sym;
 
-use crate::errors::DebugVisualizerUnreadable;
+use crate::errors::{DebugVisualizerInvalid, DebugVisualizerUnreadable};
 
-fn check_for_debugger_visualizer(
-    tcx: TyCtxt<'_>,
-    hir_id: HirId,
-    debugger_visualizers: &mut FxHashSet<DebuggerVisualizerFile>,
-) {
-    let attrs = tcx.hir().attrs(hir_id);
-    for attr in attrs {
+impl DebuggerVisualizerCollector<'_> {
+    fn check_for_debugger_visualizer(&mut self, attr: &Attribute) {
         if attr.has_name(sym::debugger_visualizer) {
-            let Some(list) = attr.meta_item_list() else {
-                continue
+            let Some(hints) = attr.meta_item_list() else {
+                self.sess.emit_err(DebugVisualizerInvalid { span: attr.span });
+                return;
             };
 
-            let meta_item = match list.len() {
-                1 => match list[0].meta_item() {
-                    Some(meta_item) => meta_item,
-                    _ => continue,
-                },
-                _ => continue,
+            let hint = if hints.len() == 1 {
+                &hints[0]
+            } else {
+                self.sess.emit_err(DebugVisualizerInvalid { span: attr.span });
+                return;
             };
 
-            let visualizer_type = match meta_item.name_or_empty() {
-                sym::natvis_file => DebuggerVisualizerType::Natvis,
-                sym::gdb_script_file => DebuggerVisualizerType::GdbPrettyPrinter,
-                _ => continue,
+            let Some(meta_item) = hint.meta_item() else {
+                self.sess.emit_err(DebugVisualizerInvalid { span: attr.span });
+                return;
             };
 
-            let file = match meta_item.value_str() {
-                Some(value) => {
-                    match resolve_path(&tcx.sess.parse_sess, value.as_str(), attr.span) {
-                        Ok(file) => file,
-                        _ => continue,
+            let (visualizer_type, visualizer_path) =
+                match (meta_item.name_or_empty(), meta_item.value_str()) {
+                    (sym::natvis_file, Some(value)) => (DebuggerVisualizerType::Natvis, value),
+                    (sym::gdb_script_file, Some(value)) => {
+                        (DebuggerVisualizerType::GdbPrettyPrinter, value)
                     }
-                }
-                None => continue,
-            };
+                    (_, _) => {
+                        self.sess.emit_err(DebugVisualizerInvalid { span: meta_item.span });
+                        return;
+                    }
+                };
+
+            let file =
+                match resolve_path(&self.sess.parse_sess, visualizer_path.as_str(), attr.span) {
+                    Ok(file) => file,
+                    Err(mut err) => {
+                        err.emit();
+                        return;
+                    }
+                };
 
             match std::fs::read(&file) {
                 Ok(contents) => {
-                    debugger_visualizers
-                        .insert(DebuggerVisualizerFile::new(Lrc::from(contents), visualizer_type));
+                    self.visualizers.push(DebuggerVisualizerFile::new(
+                        Lrc::from(contents),
+                        visualizer_type,
+                        file,
+                    ));
                 }
                 Err(error) => {
-                    tcx.sess.emit_err(DebugVisualizerUnreadable {
+                    self.sess.emit_err(DebugVisualizerUnreadable {
                         span: meta_item.span,
                         file: &file,
                         error,
@@ -65,29 +74,30 @@ fn check_for_debugger_visualizer(
     }
 }
 
-/// Traverses and collects the debugger visualizers for a specific crate.
-fn debugger_visualizers(tcx: TyCtxt<'_>, _: LocalCrate) -> Vec<DebuggerVisualizerFile> {
-    // Initialize the collector.
-    let mut debugger_visualizers = FxHashSet::default();
+struct DebuggerVisualizerCollector<'a> {
+    sess: &'a Session,
+    visualizers: Vec<DebuggerVisualizerFile>,
+}
 
-    // Collect debugger visualizers in this crate.
-    tcx.hir().for_each_module(|id| {
-        check_for_debugger_visualizer(
-            tcx,
-            tcx.hir().local_def_id_to_hir_id(id),
-            &mut debugger_visualizers,
-        )
-    });
+impl<'ast> rustc_ast::visit::Visitor<'ast> for DebuggerVisualizerCollector<'_> {
+    fn visit_attribute(&mut self, attr: &'ast Attribute) {
+        self.check_for_debugger_visualizer(attr);
+        rustc_ast::visit::walk_attribute(self, attr);
+    }
+}
 
-    // Collect debugger visualizers on the crate attributes.
-    check_for_debugger_visualizer(tcx, CRATE_HIR_ID, &mut debugger_visualizers);
+/// Traverses and collects the debugger visualizers for a specific crate.
+fn debugger_visualizers(tcx: TyCtxt<'_>, _: LocalCrate) -> Vec<DebuggerVisualizerFile> {
+    let resolver_and_krate = tcx.resolver_for_lowering(()).borrow();
+    let krate = &*resolver_and_krate.1;
 
-    // Extract out the found debugger_visualizer items.
-    let mut visualizers = debugger_visualizers.into_iter().collect::<Vec<_>>();
+    let mut visitor = DebuggerVisualizerCollector { sess: tcx.sess, visualizers: Vec::new() };
+    rustc_ast::visit::Visitor::visit_crate(&mut visitor, krate);
 
-    // Sort the visualizers so we always get a deterministic query result.
-    visualizers.sort();
-    visualizers
+    // We are collecting visualizers in AST-order, which is deterministic,
+    // so we don't need to do any explicit sorting in order to get a
+    // deterministic query result
+    visitor.visualizers
 }
 
 pub fn provide(providers: &mut Providers) {

compiler/rustc_span/src/lib.rs

@@ -1257,29 +1257,6 @@ impl SourceFileHash {
     }
 }
 
-#[derive(HashStable_Generic)]
-#[derive(Copy, PartialEq, PartialOrd, Clone, Ord, Eq, Hash, Debug, Encodable, Decodable)]
-pub enum DebuggerVisualizerType {
-    Natvis,
-    GdbPrettyPrinter,
-}
-
-/// A single debugger visualizer file.
-#[derive(HashStable_Generic)]
-#[derive(Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Encodable, Decodable)]
-pub struct DebuggerVisualizerFile {
-    /// The complete debugger visualizer source.
-    pub src: Lrc<[u8]>,
-    /// Indicates which visualizer type this targets.
-    pub visualizer_type: DebuggerVisualizerType,
-}
-
-impl DebuggerVisualizerFile {
-    pub fn new(src: Lrc<[u8]>, visualizer_type: DebuggerVisualizerType) -> Self {
-        DebuggerVisualizerFile { src, visualizer_type }
-    }
-}
-
 #[derive(Clone)]
 pub enum SourceFileLines {
     /// The source file lines, in decoded (random-access) form.

src/tools/tidy/src/ui_tests.rs

@@ -35,6 +35,7 @@ const EXTENSION_EXCEPTION_PATHS: &[&str] = &[
     "tests/ui/macros/syntax-extension-source-utils-files/includeme.fragment", // more include
     "tests/ui/unused-crate-deps/test.mk", // why would you use make
     "tests/ui/proc-macro/auxiliary/included-file.txt", // more include
+    "tests/ui/invalid/foo.natvis.xml", // sample debugger visualizer
 ];
 
 fn check_entries(tests_path: &Path, bad: &mut bool) {

tests/run-make/debugger-visualizer-dep-info/Makefile

@@ -0,0 +1,9 @@
+include ../tools.mk
+
+# This test makes sure that files referenced via #[debugger_visualizer] are
+# included in `--emit dep-info` output.
+
+all:
+	$(RUSTC) --emit dep-info main.rs
+	$(CGREP) "foo.py" < $(TMPDIR)/main.d
+	$(CGREP) "my_visualizers/bar.natvis" < $(TMPDIR)/main.d

tests/run-make/debugger-visualizer-dep-info/foo.py

@@ -0,0 +1 @@
+# empty

tests/run-make/debugger-visualizer-dep-info/main.rs

@@ -0,0 +1,12 @@
+#![debugger_visualizer(gdb_script_file = "foo.py")]
+
+fn main() {
+    const _UNUSED: u32 = {
+        mod inner {
+            #![debugger_visualizer(natvis_file = "my_visualizers/bar.natvis")]
+            pub const XYZ: u32 = 123;
+        }
+
+        inner::XYZ + 1
+    };
+}

tests/run-make/debugger-visualizer-dep-info/my_visualizers/bar.natvis

@@ -0,0 +1 @@
+<!-- empty -->

tests/run-make/incremental-debugger-visualizer/Makefile

@@ -0,0 +1,49 @@
+include ../tools.mk
+
+# This test makes sure that changes to files referenced via #[debugger_visualizer]
+# are picked up when compiling incrementally.
+
+# We have to copy the source to $(TMPDIR) because Github CI mounts the source
+# directory as readonly. We need to apply modifications to some of the source
+# file.
+SRC_DIR := $(TMPDIR)/src
+INCR_CACHE_DIR := $(TMPDIR)/incremental
+
+all:
+	rm -rf $(TMPDIR)/*
+	mkdir $(SRC_DIR)
+	cp ./foo.rs $(SRC_DIR)
+	echo "GDB script v1" > $(SRC_DIR)/foo.py
+	echo "Natvis v1" > $(SRC_DIR)/foo.natvis
+	$(RUSTC) $(SRC_DIR)/foo.rs \
+	  --crate-type=rlib \
+	  --emit metadata \
+	  -C incremental=$(INCR_CACHE_DIR) \
+	  -Z incremental-verify-ich
+	$(CGREP) "GDB script v1" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) "Natvis v1" < $(TMPDIR)/libfoo.rmeta
+
+	# Change only the GDB script and check that the change has been picked up
+	echo "GDB script v2" > $(SRC_DIR)/foo.py
+	$(RUSTC) $(SRC_DIR)/foo.rs \
+	  --crate-type=rlib \
+	  --emit metadata \
+	  -C incremental=$(INCR_CACHE_DIR) \
+	  -Z incremental-verify-ich
+
+	$(CGREP) "GDB script v2" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) -v "GDB script v1" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) "Natvis v1" < $(TMPDIR)/libfoo.rmeta
+
+	# Now change the Natvis version and check that the change has been picked up
+	echo "Natvis v2" > $(SRC_DIR)/foo.natvis
+	$(RUSTC) $(SRC_DIR)/foo.rs \
+	  --crate-type=rlib \
+	  --emit metadata \
+	  -C incremental=$(INCR_CACHE_DIR) \
+	  -Z incremental-verify-ich
+
+	$(CGREP) "GDB script v2" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) -v "GDB script v1" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) "Natvis v2" < $(TMPDIR)/libfoo.rmeta
+	$(CGREP) -v "Natvis v1" < $(TMPDIR)/libfoo.rmeta

tests/run-make/incremental-debugger-visualizer/foo.rs

@@ -0,0 +1,6 @@
+#![debugger_visualizer(natvis_file = "./foo.natvis")]
+#![debugger_visualizer(gdb_script_file = "./foo.py")]
+
+pub struct Foo {
+    pub x: u32,
+}

tests/ui/invalid/foo.natvis.xml

@@ -0,0 +1 @@
+<!-- empty -->

tests/ui/invalid/invalid-debugger-visualizer-target.rs

@@ -1,2 +1,2 @@
-#[debugger_visualizer(natvis_file = "../foo.natvis")] //~ ERROR attribute should be applied to a module
+#[debugger_visualizer(natvis_file = "./foo.natvis.xml")] //~ ERROR attribute should be applied to a module
 fn main() {}

tests/ui/invalid/invalid-debugger-visualizer-target.stderr

@@ -1,8 +1,8 @@
 error: attribute should be applied to a module
   --> $DIR/invalid-debugger-visualizer-target.rs:1:1
    |
-LL | #[debugger_visualizer(natvis_file = "../foo.natvis")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #[debugger_visualizer(natvis_file = "./foo.natvis.xml")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error