2 files changed, 20 insertions, 13 deletions
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 8ede6e41336..4ba076c64e1 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -108,7 +108,7 @@ mod signal_handler {
 }
 
 use crate::session_diagnostics::{
-    RLinkEmptyVersionNumber, RLinkEncodingVersionMismatch, RLinkRustcVersionMismatch,
+    CantEmitMIR, RLinkEmptyVersionNumber, RLinkEncodingVersionMismatch, RLinkRustcVersionMismatch,
     RLinkWrongFileType, RlinkCorruptFile, RlinkNotAFile, RlinkUnableToRead, UnstableFeatureUsage,
 };
 
@@ -243,12 +243,17 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
         return;
     }
 
+    let input = make_input(&default_early_dcx, &matches.free);
+    let has_input = input.is_some();
     let (odir, ofile) = make_output(&matches);
+
+    drop(default_early_dcx);
+
     let mut config = interface::Config {
         opts: sopts,
         crate_cfg: matches.opt_strs("cfg"),
         crate_check_cfg: matches.opt_strs("check-cfg"),
-        input: Input::File(PathBuf::new()),
+        input: input.unwrap_or(Input::File(PathBuf::new())),
         output_file: ofile,
         output_dir: odir,
         ice_file,
@@ -265,16 +270,6 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
         expanded_args: args,
     };
 
-    let has_input = match make_input(&default_early_dcx, &matches.free) {
-        Some(input) => {
-            config.input = input;
-            true // has input: normal compilation
-        }
-        None => false, // no input: we will exit early
-    };
-
-    drop(default_early_dcx);
-
     callbacks.config(&mut config);
 
     let registered_lints = config.register_lints.is_some();
@@ -379,6 +374,12 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
                 return early_exit();
             }
 
+            if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
+                if let Err(error) = rustc_mir_transform::dump_mir::emit_mir(tcx) {
+                    tcx.dcx().emit_fatal(CantEmitMIR { error });
+                }
+            }
+
             Some(Linker::codegen_and_build_linker(tcx, &*compiler.codegen_backend))
         });
 
@@ -407,7 +408,7 @@ fn dump_feature_usage_metrics(tcxt: TyCtxt<'_>, metrics_dir: &Path) {
     }
 }
 
-// Extract output directory and file from matches.
+/// Extract output directory and file from matches.
 fn make_output(matches: &getopts::Matches) -> (Option<PathBuf>, Option<OutFileName>) {
     let odir = matches.opt_str("out-dir").map(|o| PathBuf::from(&o));
     let ofile = matches.opt_str("o").map(|o| match o.as_str() {
diff --git a/compiler/rustc_driver_impl/src/session_diagnostics.rs b/compiler/rustc_driver_impl/src/session_diagnostics.rs
index e06c56539d1..774221fd396 100644
--- a/compiler/rustc_driver_impl/src/session_diagnostics.rs
+++ b/compiler/rustc_driver_impl/src/session_diagnostics.rs
@@ -3,6 +3,12 @@ use std::error::Error;
 use rustc_macros::{Diagnostic, Subdiagnostic};
 
 #[derive(Diagnostic)]
+#[diag(driver_impl_cant_emit_mir)]
+pub struct CantEmitMIR {
+    pub error: std::io::Error,
+}
+
+#[derive(Diagnostic)]
 #[diag(driver_impl_rlink_unable_to_read)]
 pub(crate) struct RlinkUnableToRead {
     pub err: std::io::Error,