Rollup merge of #84029 - drahnr:master, r=petrochenkov

add `track_path::path` fn for usage in `proc_macro`s

Adds a way to declare a dependency on external files without including them, to either re-trigger the build of a file as well as covering the use case of including dependencies within the `rustc` invocation, such that tools like `sccache`/`cachepot` are able to handle references to external files which are not included.

Ref #73921

3 files changed, 20 insertions, 3 deletions

diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 92315c4d4f6..1d73002710d 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -411,6 +411,10 @@ impl server::FreeFunctions for Rustc<'_> {
     fn track_env_var(&mut self, var: &str, value: Option<&str>) {
         self.sess.env_depinfo.borrow_mut().insert((Symbol::intern(var), value.map(Symbol::intern)));
     }
+
+    fn track_path(&mut self, path: &str) {
+        self.sess.file_depinfo.borrow_mut().insert(Symbol::intern(path));
+    }
 }
 
 impl server::TokenStream for Rustc<'_> {
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 9ea1f88b43f..c0f7ea8df49 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -28,18 +28,18 @@ use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_query_impl::Queries as TcxQueries;
 use rustc_resolve::{Resolver, ResolverArenas};
+use rustc_serialize::json;
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType, PpMode, PpSourceMode};
 use rustc_session::lint;
 use rustc_session::output::{filename_for_input, filename_for_metadata};
 use rustc_session::search_paths::PathKind;
 use rustc_session::Session;
 use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::FileName;
 use rustc_trait_selection::traits;
 use rustc_typeck as typeck;
-use tracing::{info, warn};
-
-use rustc_serialize::json;
 use tempfile::Builder as TempFileBuilder;
+use tracing::{info, warn};
 
 use std::any::Any;
 use std::cell::RefCell;
@@ -594,6 +594,16 @@ fn write_out_deps(
             .map(|fmap| escape_dep_filename(&fmap.name.prefer_local().to_string()))
             .collect();
 
+        // Account for explicitly marked-to-track files
+        // (e.g. accessed in proc macros).
+        let file_depinfo = sess.parse_sess.file_depinfo.borrow();
+        let extra_tracked_files = file_depinfo.iter().map(|path_sym| {
+            let path = PathBuf::from(&*path_sym.as_str());
+            let file = FileName::from(path);
+            escape_dep_filename(&file.prefer_local().to_string())
+        });
+        files.extend(extra_tracked_files);
+
         if let Some(ref backend) = sess.opts.debugging_opts.codegen_backend {
             files.push(backend.to_string());
         }
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 7b7878e9c7f..226fde2343a 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -133,6 +133,8 @@ pub struct ParseSess {
     pub reached_eof: Lock<bool>,
     /// Environment variables accessed during the build and their values when they exist.
     pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
+    /// File paths accessed during the build.
+    pub file_depinfo: Lock<FxHashSet<Symbol>>,
     /// All the type ascriptions expressions that have had a suggestion for likely path typo.
     pub type_ascription_path_suggestions: Lock<FxHashSet<Span>>,
     /// Whether cfg(version) should treat the current release as incomplete
@@ -165,6 +167,7 @@ impl ParseSess {
             symbol_gallery: SymbolGallery::default(),
             reached_eof: Lock::new(false),
             env_depinfo: Default::default(),
+            file_depinfo: Default::default(),
             type_ascription_path_suggestions: Default::default(),
             assume_incomplete_release: false,
             proc_macro_quoted_spans: Default::default(),