Use binary-dep-depinfo to resolve UI dependencies

Author: camsteffen

.cargo/config

@@ -5,4 +5,5 @@ lintcheck = "run --target-dir lintcheck/target --package lintcheck --bin lintche
 collect-metadata = "test --test dogfood --features metadata-collector-lint -- run_metadata_collection_lint --ignored"
 
 [build]
-rustflags = ["-Zunstable-options"]
+# -Zbinary-dep-depinfo allows us to track which rlib files to use for compiling UI tests
+rustflags = ["-Zunstable-options", "-Zbinary-dep-depinfo"]

Cargo.toml

@@ -32,11 +32,7 @@ tempfile = { version = "3.1.0", optional = true }
 cargo_metadata = "0.12"
 compiletest_rs = { version = "0.6.0", features = ["tmp"] }
 tester = "0.9"
-serde = { version = "1.0", features = ["derive"] }
-derive-new = "0.5"
 regex = "1.4"
-quote = "1"
-syn = { version = "1", features = ["full"] }
 # This is used by the `collect-metadata` alias.
 filetime = "0.2"
 
@@ -45,6 +41,15 @@ filetime = "0.2"
 # for more information.
 rustc-workspace-hack = "1.0.0"
 
+# UI test dependencies
+clippy_utils = { path = "clippy_utils" }
+derive-new = "0.5"
+if_chain = "1.0"
+itertools = "0.10.1"
+quote = "1"
+serde = { version = "1.0", features = ["derive"] }
+syn = { version = "1", features = ["full"] }
+
 [build-dependencies]
 rustc_tools_util = { version = "0.2.0", path = "rustc_tools_util" }
 

tests/compile-test.rs

@@ -2,6 +2,15 @@
 #![feature(once_cell)]
 #![feature(try_blocks)]
 
+// Some `extern crate`s are needed to ensure that UI test dependencies
+// show up in the depinfo file.
+extern crate clippy_utils;
+extern crate derive_new;
+extern crate if_chain;
+extern crate itertools;
+extern crate quote;
+extern crate syn;
+
 use compiletest_rs as compiletest;
 use compiletest_rs::common::Mode as TestMode;
 
@@ -38,6 +47,7 @@ fn third_party_crates() -> String {
     static CRATES: &[&str] = &[
         "clippy_lints",
         "clippy_utils",
+        "derive_new",
         "if_chain",
         "itertools",
         "quote",
@@ -46,50 +56,38 @@ fn third_party_crates() -> String {
         "serde_derive",
         "syn",
     ];
-    let dep_dir = cargo::TARGET_LIB.join("deps");
-    let mut crates: HashMap<&str, Vec<PathBuf>> = HashMap::with_capacity(CRATES.len());
-    let mut flags = String::new();
-    for entry in fs::read_dir(dep_dir).unwrap().flatten() {
-        let path = entry.path();
-        if let Some(name) = try {
-            let name = path.file_name()?.to_str()?;
-            let (name, _) = name.strip_suffix(".rlib")?.strip_prefix("lib")?.split_once('-')?;
-            CRATES.iter().copied().find(|&c| c == name)?
-        } {
-            flags += &format!(" --extern {}={}", name, path.display());
-            crates.entry(name).or_default().push(path.clone());
-        }
-    }
-    crates.retain(|_, paths| paths.len() > 1);
-    if !crates.is_empty() {
-        let crate_names = crates.keys().map(|s| format!("`{}`", s)).collect::<Vec<_>>().join(", ");
-        // add backslashes for an easy copy-paste `rm` command
-        let paths = crates
-            .into_values()
-            .flatten()
-            .map(|p| strip_current_dir(&p).display().to_string())
-            .collect::<Vec<_>>()
-            .join(" \\\n");
-        // Check which action should be done in order to remove compiled deps.
-        // If pre-installed version of compiler is used, `cargo clean` will do.
-        // Otherwise (for bootstrapped compiler), the dependencies directory
-        // must be removed manually.
-        let suggested_action = if std::env::var_os("RUSTC_BOOTSTRAP").is_some() {
-            "removing the stageN-tools directory"
-        } else {
-            "running `cargo clean`"
-        };
 
-        panic!(
-            "\n----------------------------------------------------------------------\n\
-            ERROR: Found multiple rlibs for crates: {}\n\
-            Try {} or remove the following files:\n\n{}\n\n\
-            For details on this error see https://github.com/rust-lang/rust-clippy/issues/7343\n\
-            ----------------------------------------------------------------------\n",
-            crate_names, suggested_action, paths
-        );
+    let depinfo = {
+        let exe_path = env::current_exe().unwrap();
+        let depinfo_filename = format!("{}.d", exe_path.file_stem().unwrap().to_str().unwrap());
+        let mut dep_info_path = exe_path;
+        dep_info_path.set_file_name(depinfo_filename);
+        std::fs::read_to_string(dep_info_path).unwrap()
+    };
+    let mut crates: HashMap<&str, &str> = HashMap::with_capacity(CRATES.len());
+    for line in depinfo.lines() {
+        let path = try {
+            let path = line.strip_suffix(':')?;
+            let part = path
+                .strip_suffix(".rlib")
+                .or_else(|| path.strip_suffix(".so"))
+                .or_else(|| path.strip_suffix(".dylib"))
+                .or_else(|| path.strip_suffix(".dll"))?;
+            let part = part.rsplit_once('-')?.0;
+            let name = part.rsplit_once(|c| matches!(c, '/' | '\\'))?.1.strip_prefix("lib")?;
+            CRATES.contains(&name).then(|| (name, path))?
+        };
+        if let Some((name, path)) = path {
+            // A dependency may be listed twice if it is available in sysroot,
+            // and the sysroot dependencies are listed first. As of the writing,
+            // this only seems to apply to if_chain.
+            crates.insert(name, path);
+        }
     }
-    flags
+    crates
+        .into_iter()
+        .map(|(name, path)| format!("--extern {}={} ", name, path))
+        .collect()
 }
 
 fn default_config() -> compiletest::Config {
@@ -105,8 +103,11 @@ fn default_config() -> compiletest::Config {
         config.compile_lib_path = path;
     }
 
+    // Using `-L dependency={}` enforces that external dependencies are added with `--extern`.
+    // This is valuable because a) it allows us to monitor what external dependencies are used
+    // and b) it ensures that conflicting rlibs are resolved properly.
     config.target_rustcflags = Some(format!(
-        "--emit=metadata -L {0} -L {1} -Dwarnings -Zui-testing {2}",
+        "--emit=metadata -L dependency={} -L dependency={} -Dwarnings -Zui-testing {}",
         host_lib().join("deps").display(),
         cargo::TARGET_LIB.join("deps").display(),
         third_party_crates(),
@@ -316,12 +317,3 @@ impl Drop for VarGuard {
         }
     }
 }
-
-fn strip_current_dir(path: &Path) -> &Path {
-    if let Ok(curr) = env::current_dir() {
-        if let Ok(stripped) = path.strip_prefix(curr) {
-            return stripped;
-        }
-    }
-    path
-}