Prepend temp files with a string per invocation of rustc

compiler/rustc_session/src/config.rs

@@ -1016,10 +1016,13 @@ impl OutFileName {
         outputs: &OutputFilenames,
         flavor: OutputType,
         codegen_unit_name: &str,
+        invocation_temp: Option<&str>,
     ) -> PathBuf {
         match *self {
             OutFileName::Real(ref path) => path.clone(),
-            OutFileName::Stdout => outputs.temp_path_for_cgu(flavor, codegen_unit_name),
+            OutFileName::Stdout => {
+                outputs.temp_path_for_cgu(flavor, codegen_unit_name, invocation_temp)
+            }
         }
     }
 
@@ -1094,21 +1097,41 @@ impl OutputFilenames {
     /// Gets the path where a compilation artifact of the given type for the
     /// given codegen unit should be placed on disk. If codegen_unit_name is
     /// None, a path distinct from those of any codegen unit will be generated.
-    pub fn temp_path_for_cgu(&self, flavor: OutputType, codegen_unit_name: &str) -> PathBuf {
+    pub fn temp_path_for_cgu(
+        &self,
+        flavor: OutputType,
+        codegen_unit_name: &str,
+        invocation_temp: Option<&str>,
+    ) -> PathBuf {
         let extension = flavor.extension();
-        self.temp_path_ext_for_cgu(extension, codegen_unit_name)
+        self.temp_path_ext_for_cgu(extension, codegen_unit_name, invocation_temp)
     }
 
     /// Like `temp_path`, but specifically for dwarf objects.
-    pub fn temp_path_dwo_for_cgu(&self, codegen_unit_name: &str) -> PathBuf {
-        self.temp_path_ext_for_cgu(DWARF_OBJECT_EXT, codegen_unit_name)
+    pub fn temp_path_dwo_for_cgu(
+        &self,
+        codegen_unit_name: &str,
+        invocation_temp: Option<&str>,
+    ) -> PathBuf {
+        self.temp_path_ext_for_cgu(DWARF_OBJECT_EXT, codegen_unit_name, invocation_temp)
     }
 
     /// Like `temp_path`, but also supports things where there is no corresponding
     /// OutputType, like noopt-bitcode or lto-bitcode.
-    pub fn temp_path_ext_for_cgu(&self, ext: &str, codegen_unit_name: &str) -> PathBuf {
+    pub fn temp_path_ext_for_cgu(
+        &self,
+        ext: &str,
+        codegen_unit_name: &str,
+        invocation_temp: Option<&str>,
+    ) -> PathBuf {
         let mut extension = codegen_unit_name.to_string();
 
+        // Append `.{invocation_temp}` to ensure temporary files are unique.
+        if let Some(rng) = invocation_temp {
+            extension.push('.');
+            extension.push_str(rng);
+        }
+
         // FIXME: This is sketchy that we're not appending `.rcgu` when the ext is empty.
         // Append `.rcgu.{ext}`.
         if !ext.is_empty() {
@@ -1144,9 +1167,10 @@ impl OutputFilenames {
         split_debuginfo_kind: SplitDebuginfo,
         split_dwarf_kind: SplitDwarfKind,
         cgu_name: &str,
+        invocation_temp: Option<&str>,
     ) -> Option<PathBuf> {
-        let obj_out = self.temp_path_for_cgu(OutputType::Object, cgu_name);
-        let dwo_out = self.temp_path_dwo_for_cgu(cgu_name);
+        let obj_out = self.temp_path_for_cgu(OutputType::Object, cgu_name, invocation_temp);
+        let dwo_out = self.temp_path_dwo_for_cgu(cgu_name, invocation_temp);
         match (split_debuginfo_kind, split_dwarf_kind) {
             (SplitDebuginfo::Off, SplitDwarfKind::Single | SplitDwarfKind::Split) => None,
             // Single mode doesn't change how DWARF is emitted, but does add Split DWARF attributes