Patch --extern arguments in phase_cargo_rustc as well

cargo-miri/bin.rs

@@ -143,6 +143,18 @@ fn get_arg_flag_value(name: &str) -> Option<String> {
     ArgFlagValueIter::new(name).next()
 }
 
+fn forward_patched_extern_arg(args: &mut impl Iterator<Item = String>, cmd: &mut Command) {
+    cmd.arg("--extern"); // always forward flag, but adjust filename:
+    let path = args.next().expect("`--extern` should be followed by a filename");
+    if let Some(lib) = path.strip_suffix(".rlib") {
+        // If this is an rlib, make it an rmeta.
+        cmd.arg(format!("{}.rmeta", lib));
+    } else {
+        // Some other extern file (e.g. a `.so`). Forward unchanged.
+        cmd.arg(path);
+    }
+}
+
 /// Returns the path to the `miri` binary
 fn find_miri() -> PathBuf {
     if let Some(path) = env::var_os("MIRI") {
@@ -553,7 +565,7 @@ fn phase_cargo_miri(mut args: env::Args) {
     exec(cmd)
 }
 
-fn phase_cargo_rustc(args: env::Args) {
+fn phase_cargo_rustc(mut args: env::Args) {
     /// Determines if we are being invoked (as rustc) to build a crate for
     /// the "target" architecture, in contrast to the "host" architecture.
     /// Host crates are for build scripts and proc macros and still need to
@@ -596,15 +608,6 @@ fn phase_cargo_rustc(args: env::Args) {
     let target_crate = is_target_crate();
     let print = get_arg_flag_value("--print").is_some(); // whether this is cargo passing `--print` to get some infos
 
-    // cdylib is just skipped, we cannot interpret it and do not need it
-    // for the rest of the build either.
-    if get_arg_flag_value("--crate-type").as_deref() == Some("cdylib") {
-        if verbose {
-            eprint!("[cargo-miri rustc] (cdylib skipped)");
-        }
-        return;
-    }
-
     let store_json = |info: CrateRunInfo| {
         let filename = out_filename("", "");
         if verbose {
@@ -643,7 +646,7 @@ fn phase_cargo_rustc(args: env::Args) {
     if !print && target_crate {
         // Forward arguments, but remove "link" from "--emit" to make this a check-only build.
         let emit_flag = "--emit";
-        for arg in args {
+        while let Some(arg) = args.next() {
             if arg.starts_with(emit_flag) {
                 // Patch this argument. First, extract its value.
                 let val = &arg[emit_flag.len()..];
@@ -659,6 +662,10 @@ fn phase_cargo_rustc(args: env::Args) {
                     }
                 }
                 cmd.arg(format!("{}={}", emit_flag, val.join(",")));
+            } else if arg == "--extern" {
+                // Patch `--extern` filenames, since Cargo sometimes passes stub `.rlib` files:
+                // https://github.com/rust-lang/miri/issues/1705
+                forward_patched_extern_arg(&mut args, &mut cmd);
             } else {
                 cmd.arg(arg);
             }
@@ -734,21 +741,11 @@ fn phase_cargo_runner(binary: &Path, binary_args: env::Args) {
     // but when we run here, cargo does not interpret the JSON any more. `--json`
     // then also nees to be dropped.
     let mut args = info.args.into_iter();
-    let extern_flag = "--extern";
     let error_format_flag = "--error-format";
     let json_flag = "--json";
     while let Some(arg) = args.next() {
-        if arg == extern_flag {
-            cmd.arg(extern_flag); // always forward flag, but adjust filename
-            // `--extern` is always passed as a separate argument by cargo.
-            let next_arg = args.next().expect("`--extern` should be followed by a filename");
-            if let Some(next_lib) = next_arg.strip_suffix(".rlib") {
-                // If this is an rlib, make it an rmeta.
-                cmd.arg(format!("{}.rmeta", next_lib));
-            } else {
-                // Some other extern file (e.g., a `.so`). Forward unchanged.
-                cmd.arg(next_arg);
-            }
+        if arg == "--extern" {
+            forward_patched_extern_arg(&mut args, &mut cmd);
         } else if arg.starts_with(error_format_flag) {
             let suffix = &arg[error_format_flag.len()..];
             assert!(suffix.starts_with('='));

test-cargo-miri/Cargo.toml

@@ -9,8 +9,10 @@ edition = "2018"
 
 [dependencies]
 byteorder = "1.0"
+cdylib = { path = "cdylib" }
 issue_1567 = { path = "issue-1567" }
 issue_1691 = { path = "issue-1691" }
+issue_1705 = { path = "issue-1705" }
 
 [dev-dependencies]
 rand = { version = "0.7", features = ["small_rng"] }

test-cargo-miri/cdylib/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "cdylib"
+version = "0.1.0"
+authors = ["Miri Team"]
+edition = "2018"
+
+[lib]
+# cargo-miri used to handle `cdylib` crate-type specially (https://github.com/rust-lang/miri/pull/1577).
+crate-type = ["cdylib"]
+
+[dependencies]
+byteorder = "1.0"

test-cargo-miri/cdylib/src/lib.rs

@@ -0,0 +1,6 @@
+use byteorder::{BigEndian, ByteOrder};
+
+#[no_mangle]
+extern "C" fn use_the_dependency() {
+    let _n = <BigEndian as ByteOrder>::read_u64(&[1,2,3,4,5,6,7,8]);
+}

test-cargo-miri/issue-1705/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "issue_1705"
+version = "0.1.0"
+authors = ["Miri Team"]
+edition = "2018"
+
+[lib]
+crate-type = ["lib", "staticlib", "cdylib"]
+
+[dependencies]
+byteorder = "1.0"

test-cargo-miri/issue-1705/src/lib.rs

@@ -0,0 +1,5 @@
+use byteorder::{LittleEndian, ByteOrder};
+
+pub fn use_the_dependency() {
+    let _n = <LittleEndian as ByteOrder>::read_u32(&[1,2,3,4]);
+}

test-cargo-miri/src/lib.rs

@@ -3,5 +3,7 @@
 /// assert!(cargo_miri_test::make_true());
 /// ```
 pub fn make_true() -> bool {
+    issue_1567::use_the_dependency();
+    issue_1705::use_the_dependency();
     issue_1691::use_me()
 }