add track_path::path fn for usage in proc_macros

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<'_> {

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());
         }

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(),

library/proc_macro/src/bridge/mod.rs

@@ -55,6 +55,7 @@ macro_rules! with_api {
             FreeFunctions {
                 fn drop($self: $S::FreeFunctions);
                 fn track_env_var(var: &str, value: Option<&str>);
+                fn track_path(path: &str);
             },
             TokenStream {
                 fn drop($self: $S::TokenStream);

library/proc_macro/src/lib.rs

@@ -1235,3 +1235,17 @@ pub mod tracked_env {
         value
     }
 }
+
+/// Tracked access to additional files.
+#[unstable(feature = "track_path", issue = "73921")]
+pub mod tracked_path {
+
+    /// Track a file explicitly.
+    ///
+    /// Commonly used for tracking asset preprocessing.
+    #[unstable(feature = "track_path", issue = "73921")]
+    pub fn path<P: AsRef<str>>(path: P) {
+        let path: &str = path.as_ref();
+        crate::bridge::client::FreeFunctions::track_path(path);
+    }
+}

src/test/run-make/track-path-dep-info/Makefile

@@ -0,0 +1,13 @@
+-include ../../run-make-fulldeps/tools.mk
+
+# FIXME(eddyb) provide `HOST_RUSTC` and `TARGET_RUSTC`
+# instead of hardcoding them everywhere they're needed.
+ifeq ($(IS_MUSL_HOST),1)
+ADDITIONAL_ARGS := $(RUSTFLAGS)
+endif
+
+all:
+	# Proc macro
+	$(BARE_RUSTC) $(ADDITIONAL_ARGS) --out-dir $(TMPDIR) macro_def.rs
+	EXISTING_PROC_MACRO_ENV=1 $(RUSTC) --emit dep-info macro_use.rs
+	$(CGREP) "emojis.txt:" < $(TMPDIR)/macro_use.d

src/test/run-make/track-path-dep-info/emojis.txt

@@ -0,0 +1 @@
+👾👾👾👾👾👾

src/test/run-make/track-path-dep-info/macro_def.rs

@@ -0,0 +1,11 @@
+#![feature(track_path)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro]
+pub fn access_tracked_paths(_: TokenStream) -> TokenStream {
+    tracked_path::path("emojis.txt");
+    TokenStream::new()
+}

src/test/run-make/track-path-dep-info/macro_use.rs

@@ -0,0 +1,6 @@
+#[macro_use]
+extern crate macro_def;
+
+access_tracked_paths!();
+
+fn main() {}