Auto merge of #83846 - torhovland:issue-10971, r=davidtwco

Added the --temps-dir option

Fixes #10971.

The new `--temps-dir` option puts intermediate files in a user-specified directory. This provides a fix for the issue where parallel invocations of rustc would overwrite each other's intermediate files.

No files are kept in the intermediate directory unless `-C save-temps=yes`.

If additional files are specifically requested using `--emit asm,llvm-bc,llvm-ir,obj,metadata,link,dep-info,mir`, these will be put in the output directory rather than the intermediate directory.

This is a backward-compatible change, i.e. if `--temps-dir` is not specified, the behavior is the same as before.

compiler/rustc_driver/src/lib.rs

@@ -267,6 +267,7 @@ fn run_compiler(
                         None,
                         compiler.output_dir(),
                         compiler.output_file(),
+                        compiler.temps_dir(),
                     );
 
                     if should_stop == Compilation::Stop {
@@ -295,6 +296,7 @@ fn run_compiler(
             Some(compiler.input()),
             compiler.output_dir(),
             compiler.output_file(),
+            compiler.temps_dir(),
         )
         .and_then(|| {
             RustcDefaultCalls::list_metadata(
@@ -647,6 +649,7 @@ impl RustcDefaultCalls {
         input: Option<&Input>,
         odir: &Option<PathBuf>,
         ofile: &Option<PathBuf>,
+        temps_dir: &Option<PathBuf>,
     ) -> Compilation {
         use rustc_session::config::PrintRequest::*;
         // PrintRequest::NativeStaticLibs is special - printed during linking
@@ -685,7 +688,7 @@ impl RustcDefaultCalls {
                     });
                     let attrs = attrs.as_ref().unwrap();
                     let t_outputs = rustc_interface::util::build_output_filenames(
-                        input, odir, ofile, attrs, sess,
+                        input, odir, ofile, temps_dir, attrs, sess,
                     );
                     let id = rustc_session::output::find_crate_name(sess, attrs, input);
                     if *req == PrintRequest::CrateName {

compiler/rustc_interface/src/interface.rs

@@ -36,6 +36,7 @@ pub struct Compiler {
     pub(crate) input_path: Option<PathBuf>,
     pub(crate) output_dir: Option<PathBuf>,
     pub(crate) output_file: Option<PathBuf>,
+    pub(crate) temps_dir: Option<PathBuf>,
     pub(crate) register_lints: Option<Box<dyn Fn(&Session, &mut LintStore) + Send + Sync>>,
     pub(crate) override_queries:
         Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::ExternProviders)>,
@@ -57,6 +58,9 @@ impl Compiler {
     pub fn output_file(&self) -> &Option<PathBuf> {
         &self.output_file
     }
+    pub fn temps_dir(&self) -> &Option<PathBuf> {
+        &self.temps_dir
+    }
     pub fn register_lints(&self) -> &Option<Box<dyn Fn(&Session, &mut LintStore) + Send + Sync>> {
         &self.register_lints
     }
@@ -65,7 +69,14 @@ impl Compiler {
         sess: &Session,
         attrs: &[ast::Attribute],
     ) -> OutputFilenames {
-        util::build_output_filenames(&self.input, &self.output_dir, &self.output_file, attrs, sess)
+        util::build_output_filenames(
+            &self.input,
+            &self.output_dir,
+            &self.output_file,
+            &self.temps_dir,
+            attrs,
+            sess,
+        )
     }
 }
 
@@ -186,13 +197,16 @@ pub fn create_compiler_and_run<R>(config: Config, f: impl FnOnce(&Compiler) -> R
         );
     }
 
+    let temps_dir = sess.opts.debugging_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
+
     let compiler = Compiler {
         sess,
         codegen_backend,
         input: config.input,
         input_path: config.input_path,
         output_dir: config.output_dir,
         output_file: config.output_file,
+        temps_dir,
         register_lints: config.register_lints,
         override_queries: config.override_queries,
     };

compiler/rustc_interface/src/passes.rs

@@ -692,6 +692,7 @@ pub fn prepare_outputs(
         &compiler.input,
         &compiler.output_dir,
         &compiler.output_file,
+        &compiler.temps_dir,
         &krate.attrs,
         sess,
     );
@@ -722,6 +723,13 @@ pub fn prepare_outputs(
         }
     }
 
+    if let Some(ref dir) = compiler.temps_dir {
+        if fs::create_dir_all(dir).is_err() {
+            sess.err("failed to find or create the directory specified by `--temps-dir`");
+            return Err(ErrorReported);
+        }
+    }
+
     write_out_deps(sess, boxed_resolver, &outputs, &output_paths);
 
     let only_dep_info = sess.opts.output_types.contains_key(&OutputType::DepInfo)

compiler/rustc_interface/src/tests.rs

@@ -685,6 +685,7 @@ fn test_debugging_options_tracking_hash() {
     untracked!(span_debug, true);
     untracked!(span_free_formats, true);
     untracked!(strip, Strip::Debuginfo);
+    untracked!(temps_dir, Some(String::from("abc")));
     untracked!(terminal_width, Some(80));
     untracked!(threads, 99);
     untracked!(time, true);

compiler/rustc_interface/src/util.rs

@@ -604,6 +604,7 @@ pub fn build_output_filenames(
     input: &Input,
     odir: &Option<PathBuf>,
     ofile: &Option<PathBuf>,
+    temps_dir: &Option<PathBuf>,
     attrs: &[ast::Attribute],
     sess: &Session,
 ) -> OutputFilenames {
@@ -626,6 +627,7 @@ pub fn build_output_filenames(
                 dirpath,
                 stem,
                 None,
+                temps_dir.clone(),
                 sess.opts.cg.extra_filename.clone(),
                 sess.opts.output_types.clone(),
             )
@@ -654,6 +656,7 @@ pub fn build_output_filenames(
                 out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
                 out_file.file_stem().unwrap_or_default().to_str().unwrap().to_string(),
                 ofile,
+                temps_dir.clone(),
                 sess.opts.cg.extra_filename.clone(),
                 sess.opts.output_types.clone(),
             )

compiler/rustc_session/src/config.rs

@@ -578,6 +578,7 @@ pub struct OutputFilenames {
     pub out_directory: PathBuf,
     filestem: String,
     pub single_output_file: Option<PathBuf>,
+    pub temps_directory: Option<PathBuf>,
     pub outputs: OutputTypes,
 }
 
@@ -592,12 +593,14 @@ impl OutputFilenames {
         out_directory: PathBuf,
         out_filestem: String,
         single_output_file: Option<PathBuf>,
+        temps_directory: Option<PathBuf>,
         extra: String,
         outputs: OutputTypes,
     ) -> Self {
         OutputFilenames {
             out_directory,
             single_output_file,
+            temps_directory,
             outputs,
             filestem: format!("{}{}", out_filestem, extra),
         }
@@ -608,7 +611,14 @@ impl OutputFilenames {
             .get(&flavor)
             .and_then(|p| p.to_owned())
             .or_else(|| self.single_output_file.clone())
-            .unwrap_or_else(|| self.temp_path(flavor, None))
+            .unwrap_or_else(|| self.output_path(flavor))
+    }
+
+    /// Gets the output path where a compilation artifact of the given type
+    /// should be placed on disk.
+    pub fn output_path(&self, flavor: OutputType) -> PathBuf {
+        let extension = flavor.extension();
+        self.with_directory_and_extension(&self.out_directory, &extension)
     }
 
     /// Gets the path where a compilation artifact of the given type for the
@@ -643,11 +653,17 @@ impl OutputFilenames {
             extension.push_str(ext);
         }
 
-        self.with_extension(&extension)
+        let temps_directory = self.temps_directory.as_ref().unwrap_or(&self.out_directory);
+
+        self.with_directory_and_extension(&temps_directory, &extension)
     }
 
     pub fn with_extension(&self, extension: &str) -> PathBuf {
-        let mut path = self.out_directory.join(&self.filestem);
+        self.with_directory_and_extension(&self.out_directory, extension)
+    }
+
+    fn with_directory_and_extension(&self, directory: &PathBuf, extension: &str) -> PathBuf {
+        let mut path = directory.join(&self.filestem);
         path.set_extension(extension);
         path
     }

compiler/rustc_session/src/options.rs

@@ -1331,6 +1331,8 @@ options! {
         "which mangling version to use for symbol names ('legacy' (default) or 'v0')"),
     teach: bool = (false, parse_bool, [TRACKED],
         "show extended diagnostic help (default: no)"),
+    temps_dir: Option<String> = (None, parse_opt_string, [UNTRACKED],
+        "the directory the intermediate files are written to"),
     terminal_width: Option<usize> = (None, parse_opt_number, [UNTRACKED],
         "set the current terminal width"),
     tune_cpu: Option<String> = (None, parse_opt_string, [TRACKED],

src/doc/unstable-book/src/compiler-flags/temps-dir.md

@@ -0,0 +1,10 @@
+# `temps-dir`
+
+--------------------
+
+The `-Ztemps-dir` compiler flag specifies the directory to write the
+intermediate files in. If not set, the output directory is used. This option is
+useful if you are running more than one instance of `rustc` (e.g. with different
+`--crate-type` settings), and you need to make sure they are not overwriting
+each other's intermediate files. No files are kept unless `-C save-temps=yes` is
+also set.

src/test/run-make/issue-10971-temps-dir/Makefile

@@ -0,0 +1,10 @@
+-include ../../run-make-fulldeps/tools.mk
+
+# Regression test for issue #10971
+# Running two invocations in parallel would overwrite each other's temp files.
+
+all:
+	touch $(TMPDIR)/lib.rs
+
+	$(RUSTC) --crate-type=lib -Z temps-dir=$(TMPDIR)/temp1 $(TMPDIR)/lib.rs & \
+	$(RUSTC) --crate-type=staticlib -Z temps-dir=$(TMPDIR)/temp2 $(TMPDIR)/lib.rs