make sure subcrate tests have the right cwd

Author: RalfJung

README.md

@@ -244,6 +244,10 @@ different Miri binaries, and as such worth documenting:
 * `MIRI_BE_RUSTC` when set to any value tells the Miri driver to actually not
   interpret the code but compile it like rustc would. This is useful to be sure
   that the compiled `rlib`s are compatible with Miri.
+* `MIRI_CWD` when set to any value tells the Miri driver to change to the given
+  directory after loading all the source files, but before commencing
+  interpretation. This is useful if the interpreted program wants a different
+  working directory at run-time than at build-time.
 
 ## Miri `extern` functions
 

cargo-miri/bin.rs

@@ -43,14 +43,17 @@ struct CrateRunInfo {
     args: Vec<String>,
     /// The environment.
     env: Vec<(OsString, OsString)>,
+    /// The current working directory.
+    current_dir: OsString,
 }
 
 impl CrateRunInfo {
     /// Gather all the information we need.
     fn collect(args: env::Args) -> Self {
         let args = args.collect();
         let env = env::vars_os().collect();
-        CrateRunInfo { args, env }
+        let current_dir = env::current_dir().unwrap().into_os_string();
+        CrateRunInfo { args, env, current_dir }
     }
 
     fn store(&self, filename: &Path) {
@@ -669,6 +672,11 @@ fn phase_cargo_runner(binary: &Path, binary_args: env::Args) {
     cmd.arg("--");
     cmd.args(binary_args);
 
+    // Make sure we use the build-time working directory for interpreting Miri/rustc arguments.
+    // But then we need to switch to the run-time one, which we instruct Miri do do by setting `MIRI_CWD`.
+    cmd.current_dir(info.current_dir);
+    cmd.env("MIRI_CWD", env::current_dir().unwrap());
+
     // Run it.
     if verbose {
         eprintln!("[cargo-miri runner] {:?}", cmd);

src/bin/miri.rs

@@ -45,6 +45,11 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
             // Add filename to `miri` arguments.
             config.args.insert(0, compiler.input().filestem().to_string());
 
+            // Adjust working directory for interpretation.
+            if let Some(cwd) = env::var_os("MIRI_CWD") {
+                env::set_current_dir(cwd).unwrap();
+            }
+
             if let Some(return_code) = miri::eval_main(tcx, entry_def_id.to_def_id(), config) {
                 std::process::exit(
                     i32::try_from(return_code).expect("Return value was too large!"),

test-cargo-miri/Cargo.toml

@@ -16,7 +16,3 @@ num_cpus = "1.10.1"
 
 [lib]
 test = false # test that this is respected (will show in the output)
-
-[[test]]
-name = "no-harness"
-harness = false

test-cargo-miri/run-test.py

@@ -50,7 +50,7 @@ def test(name, cmd, stdout_ref, stderr_ref, stdin=b'', env={}):
         fail("stderr does not match reference")
 
 def test_cargo_miri_run():
-    test("`cargo miri run` (without isolation)",
+    test("`cargo miri run` (no isolation)",
         cargo_miri("run"),
         "stdout.ref1", "stderr.ref1",
         stdin=b'12\n21\n',
@@ -61,9 +61,9 @@ def test_cargo_miri_run():
     )
     test("`cargo miri run` (with arguments and target)",
         cargo_miri("run") + ["--bin", "cargo-miri-test", "--", "hello world", '"hello world"'],
-        "stdout.ref2", "stderr.ref2"
+        "stdout.ref2", "stderr.ref2",
     )
-    test("`cargo miri run` (subcrate)",
+    test("`cargo miri run` (subcrate, no ioslation)",
         cargo_miri("run") + ["-p", "subcrate"],
         "stdout.ref3", "stderr.ref3",
         env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
@@ -76,25 +76,30 @@ def test_cargo_miri_test():
 
     test("`cargo miri test`",
         cargo_miri("test"),
-        "test.stdout.ref1",rustdoc_ref,
+        "test.stdout.ref1", rustdoc_ref,
         env={'MIRIFLAGS': "-Zmiri-seed=feed"},
     )
+    test("`cargo miri test` (no isolation)",
+        cargo_miri("test"),
+        "test.stdout.ref1", rustdoc_ref,
+        env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
+    )
     test("`cargo miri test` (with filter)",
         cargo_miri("test") + ["--", "--format=pretty", "le1"],
-        "test.stdout.ref2", rustdoc_ref
-    )
-    test("`cargo miri test` (without isolation)",
-        cargo_miri("test") + ["--", "--format=pretty", "num_cpus"],
-        "test.stdout.ref3", rustdoc_ref,
-        env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
+        "test.stdout.ref2", rustdoc_ref,
     )
     test("`cargo miri test` (test target)",
         cargo_miri("test") + ["--test", "test", "--", "--format=pretty"],
-        "test.stdout.ref4", "test.stderr.ref2"
+        "test.stdout.ref3", "test.stderr.ref2",
     )
     test("`cargo miri test` (bin target)",
         cargo_miri("test") + ["--bin", "cargo-miri-test", "--", "--format=pretty"],
-        "test.stdout.ref5", "test.stderr.ref2"
+        "test.stdout.ref4", "test.stderr.ref2",
+    )
+    test("`cargo miri test` (subcrate)",
+        cargo_miri("test") + ["-p", "subcrate"],
+        "test.stdout.ref5", "test.stderr.ref2",
+        env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
     )
 
 os.chdir(os.path.dirname(os.path.realpath(__file__)))

test-cargo-miri/subcrate/Cargo.toml

@@ -7,3 +7,8 @@ edition = "2018"
 [[bin]]
 name = "subcrate"
 path = "main.rs"
+
+[[test]]
+name = "subtest"
+path = "test.rs"
+harness = false

test-cargo-miri/subcrate/test.rs

@@ -0,0 +1,11 @@
+use std::env;
+use std::path::PathBuf;
+
+fn main() {
+    println!("subcrate testing");
+
+    let env_dir = env::current_dir().unwrap();
+    let crate_dir = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    // CWD should be crate root.
+    assert_eq!(env_dir, crate_dir);
+}

test-cargo-miri/test.stdout.ref1

@@ -3,7 +3,6 @@ running 1 test
 .
 test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
 
-no-harness test
 
 running 8 tests
 ..i.....

test-cargo-miri/test.stdout.ref2

@@ -3,7 +3,6 @@ running 0 tests
 
 test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 1 filtered out
 
-no-harness test
 
 running 1 test
 test simple1 ... ok

test-cargo-miri/test.stdout.ref3

@@ -1,12 +1,13 @@
 
-running 0 tests
-
-test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 1 filtered out
-
-no-harness test
-
-running 1 test
+running 8 tests
+test cargo_env ... ok
+test do_panic ... ok
+test does_not_work_on_miri ... ignored
+test entropy_rng ... ok
+test fail_index_check ... ok
 test num_cpus ... ok
+test simple1 ... ok
+test simple2 ... ok
 
-test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 7 filtered out
+test result: ok. 7 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out