From 2205ed5bbb2fb8fb6c3b6a619815513f9d4c8038 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 11 Sep 2020 15:05:05 +0200
Subject: [PATCH] show proper warning about not running doctests

---
 cargo-miri/bin.rs                | 22 ++++++++++++++++++++--
 test-cargo-miri/Cargo.toml       |  3 +--
 test-cargo-miri/run-test.py      |  4 ++--
 test-cargo-miri/test.stderr.ref  |  1 +
 test-cargo-miri/test.stderr.ref2 |  0
 5 files changed, 24 insertions(+), 6 deletions(-)
 create mode 100644 test-cargo-miri/test.stderr.ref2

diff --git a/cargo-miri/bin.rs b/cargo-miri/bin.rs
index 70f8888676f..6dbaa9791df 100644
--- a/cargo-miri/bin.rs
+++ b/cargo-miri/bin.rs
@@ -442,6 +442,9 @@ fn phase_cargo_miri(mut args: env::Args) {
     let runner_env_name = format!("CARGO_TARGET_{}_RUNNER", target.to_uppercase().replace('-', "_"));
     cmd.env(runner_env_name, &miri_path);
 
+    // Set rustdoc to us as well, so we can make it do nothing (see issue #584).
+    cmd.env("RUSTDOC", &miri_path);
+
     // Run cargo.
     if verbose {
         cmd.env("MIRI_VERBOSE", ""); // This makes the other phases verbose.
@@ -571,7 +574,7 @@ fn phase_cargo_rustc(args: env::Args) {
     }
 }
 
-fn phase_cargo_runner(binary: &str, binary_args: env::Args) {
+fn phase_cargo_runner(binary: &Path, binary_args: env::Args) {
     let verbose = std::env::var_os("MIRI_VERBOSE").is_some();
 
     let file = File::open(&binary)
@@ -659,10 +662,25 @@ fn main() {
     //   binary crates for later interpretation.
     // - When we are executed due to CARGO_TARGET_RUNNER, we start interpretation based on the
     //   flags that were stored earlier.
+    // On top of that, we are also called as RUSTDOC, but that is just a stub currently.
     match args.next().as_deref() {
         Some("miri") => phase_cargo_miri(args),
         Some("rustc") => phase_cargo_rustc(args),
-        Some(binary) => phase_cargo_runner(binary, args),
+        Some(arg) => {
+            // We have to distinguish the "runner" and "rustfmt" cases.
+            // As runner, the first argument is the binary (a file that should exist, with an absolute path);
+            // as rustfmt, the first argument is a flag (`--something`).
+            let binary = Path::new(arg);
+            if binary.exists() {
+                assert!(!arg.starts_with("--")); // not a flag
+                phase_cargo_runner(binary, args);
+            } else if arg.starts_with("--") {
+                // We are rustdoc.
+                eprintln!("Running doctests is not currently supported by Miri.")
+            } else {
+                show_error(format!("`cargo-miri` called with unexpected first argument `{}`; please only invoke this binary through `cargo miri`", arg));
+            }
+        }
         _ => show_error(format!("`cargo-miri` called without first argument; please only invoke this binary through `cargo miri`")),
     }
 }
diff --git a/test-cargo-miri/Cargo.toml b/test-cargo-miri/Cargo.toml
index 68970d7d166..6bc11ef0cc5 100644
--- a/test-cargo-miri/Cargo.toml
+++ b/test-cargo-miri/Cargo.toml
@@ -12,5 +12,4 @@ rand = { version = "0.7", features = ["small_rng"] }
 num_cpus = "1.10.1"
 
 [lib]
-test = false
-doctest = false # FIXME: doctests should be skipped automatically until we can run them...
+test = false # test that this is respected (will show in the output)
diff --git a/test-cargo-miri/run-test.py b/test-cargo-miri/run-test.py
index 877a2a57061..82b3b88a633 100755
--- a/test-cargo-miri/run-test.py
+++ b/test-cargo-miri/run-test.py
@@ -78,11 +78,11 @@ def test_cargo_miri_test():
     )
     test("cargo miri test (test target)",
         cargo_miri("test") + ["--test", "test", "--", "--format=pretty"],
-        "test.stdout.ref4", "test.stderr.ref"
+        "test.stdout.ref4", "test.stderr.ref2"
     )
     test("cargo miri test (bin target)",
         cargo_miri("test") + ["--bin", "cargo-miri-test", "--", "--format=pretty"],
-        "test.stdout.ref5", "test.stderr.ref"
+        "test.stdout.ref5", "test.stderr.ref2"
     )
 
 os.chdir(os.path.dirname(os.path.realpath(__file__)))
diff --git a/test-cargo-miri/test.stderr.ref b/test-cargo-miri/test.stderr.ref
index e69de29bb2d..a310169e305 100644
--- a/test-cargo-miri/test.stderr.ref
+++ b/test-cargo-miri/test.stderr.ref
@@ -0,0 +1 @@
+Running doctests is not currently supported by Miri.
diff --git a/test-cargo-miri/test.stderr.ref2 b/test-cargo-miri/test.stderr.ref2
new file mode 100644
index 00000000000..e69de29bb2d