Auto merge of rust-lang#8774 - hellow554:cargo-rust-version, r=flip1995

try reading rust-version from Cargo.toml

Cargo.toml can contain a field `rust-version`, that acts like a MSRV of
clippy.toml file: https://doc.rust-lang.org/cargo/reference/manifest.html#the-rust-version-field
This will try to read that field and use it, if the clippy.toml config
has no `msrv` entry

changelog: respect `rust-version` from `Cargo.toml`

closes rust-lang#8746
closes rust-lang#7765

Author: bors

Cargo.toml

@@ -31,6 +31,7 @@ termize = "0.1"
 compiletest_rs = { version = "0.8", features = ["tmp"] }
 tester = "0.9"
 regex = "1.5"
+toml = "0.5"
 # This is used by the `collect-metadata` alias.
 filetime = "0.2"
 

README.md

@@ -214,6 +214,14 @@ specifying the minimum supported Rust version (MSRV) in the clippy configuration
 msrv = "1.30.0"
 ```
 
+Alternatively, the [`rust-version` field](https://doc.rust-lang.org/cargo/reference/manifest.html#the-rust-version-field)
+in the `Cargo.toml` can be used.
+
+```toml
+# Cargo.toml
+rust-version = "1.30"
+```
+
 The MSRV can also be specified as an inner attribute, like below.
 
 ```rust

clippy_lints/src/lib.rs

@@ -53,6 +53,7 @@ extern crate clippy_utils;
 use clippy_utils::parse_msrv;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_lint::LintId;
+use rustc_semver::RustcVersion;
 use rustc_session::Session;
 
 /// Macro used to declare a Clippy lint.
@@ -452,6 +453,39 @@ pub fn register_pre_expansion_lints(store: &mut rustc_lint::LintStore, sess: &Se
     store.register_pre_expansion_pass(move || Box::new(attrs::EarlyAttributes { msrv }));
 }
 
+fn read_msrv(conf: &Conf, sess: &Session) -> Option<RustcVersion> {
+    let cargo_msrv = std::env::var("CARGO_PKG_RUST_VERSION")
+        .ok()
+        .and_then(|v| parse_msrv(&v, None, None));
+    let clippy_msrv = conf.msrv.as_ref().and_then(|s| {
+        parse_msrv(s, None, None).or_else(|| {
+            sess.err(&format!(
+                "error reading Clippy's configuration file. `{}` is not a valid Rust version",
+                s
+            ));
+            None
+        })
+    });
+
+    if let Some(cargo_msrv) = cargo_msrv {
+        if let Some(clippy_msrv) = clippy_msrv {
+            // if both files have an msrv, let's compare them and emit a warning if they differ
+            if clippy_msrv != cargo_msrv {
+                sess.warn(&format!(
+                    "the MSRV in `clippy.toml` and `Cargo.toml` differ; using `{}` from `clippy.toml`",
+                    clippy_msrv
+                ));
+            }
+
+            Some(clippy_msrv)
+        } else {
+            Some(cargo_msrv)
+        }
+    } else {
+        clippy_msrv
+    }
+}
+
 #[doc(hidden)]
 pub fn read_conf(sess: &Session) -> Conf {
     let file_name = match utils::conf::lookup_conf_file() {
@@ -467,12 +501,11 @@ pub fn read_conf(sess: &Session) -> Conf {
     let TryConf { conf, errors } = utils::conf::read(&file_name);
     // all conf errors are non-fatal, we just use the default conf in case of error
     for error in errors {
-        sess.struct_err(&format!(
+        sess.err(&format!(
             "error reading Clippy's configuration file `{}`: {}",
             file_name.display(),
             format_error(error)
-        ))
-        .emit();
+        ));
     }
 
     conf
@@ -579,16 +612,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(non_octal_unix_permissions::NonOctalUnixPermissions));
     store.register_early_pass(|| Box::new(unnecessary_self_imports::UnnecessarySelfImports));
 
-    let msrv = conf.msrv.as_ref().and_then(|s| {
-        parse_msrv(s, None, None).or_else(|| {
-            sess.err(&format!(
-                "error reading Clippy's configuration file. `{}` is not a valid Rust version",
-                s
-            ));
-            None
-        })
-    });
-
+    let msrv = read_msrv(conf, sess);
     let avoid_breaking_exported_api = conf.avoid_breaking_exported_api;
     let allow_expect_in_tests = conf.allow_expect_in_tests;
     let allow_unwrap_in_tests = conf.allow_unwrap_in_tests;

tests/compile-test.rs

@@ -130,7 +130,7 @@ fn base_config(test_dir: &str) -> compiletest::Config {
     let mut config = compiletest::Config {
         edition: Some("2021".into()),
         mode: TestMode::Ui,
-        ..compiletest::Config::default()
+        ..Default::default()
     };
 
     if let Ok(filters) = env::var("TESTNAME") {
@@ -286,6 +286,24 @@ fn run_ui_cargo() {
                 }
 
                 env::set_current_dir(&src_path)?;
+
+                let cargo_toml_path = case.path().join("Cargo.toml");
+                let cargo_content = fs::read(&cargo_toml_path)?;
+                let cargo_parsed: toml::Value = toml::from_str(
+                    std::str::from_utf8(&cargo_content).expect("`Cargo.toml` is not a valid utf-8 file!"),
+                )
+                .expect("Can't parse `Cargo.toml`");
+
+                let _g = VarGuard::set("CARGO_MANIFEST_DIR", case.path());
+                let _h = VarGuard::set(
+                    "CARGO_PKG_RUST_VERSION",
+                    cargo_parsed
+                        .get("package")
+                        .and_then(|p| p.get("rust-version"))
+                        .and_then(toml::Value::as_str)
+                        .unwrap_or(""),
+                );
+
                 for file in fs::read_dir(&src_path)? {
                     let file = file?;
                     if file.file_type()?.is_dir() {

tests/ui-cargo/cargo_rust_version/fail_both_diff/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "fail-both-diff"
+version = "0.1.0"
+rust-version = "1.56"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tests/ui-cargo/cargo_rust_version/fail_both_diff/clippy.toml

@@ -0,0 +1 @@
+msrv = "1.59"

tests/ui-cargo/cargo_rust_version/fail_both_diff/src/main.rs

@@ -0,0 +1,11 @@
+#![deny(clippy::use_self)]
+
+pub struct Foo;
+
+impl Foo {
+    pub fn bar() -> Foo {
+        Foo
+    }
+}
+
+fn main() {}

tests/ui-cargo/cargo_rust_version/fail_both_diff/src/main.stderr

@@ -0,0 +1,16 @@
+warning: the MSRV in `clippy.toml` and `Cargo.toml` differ; using `1.59.0` from `clippy.toml`
+
+error: unnecessary structure name repetition
+  --> $DIR/main.rs:6:21
+   |
+LL |     pub fn bar() -> Foo {
+   |                     ^^^ help: use the applicable keyword: `Self`
+   |
+note: the lint level is defined here
+  --> $DIR/main.rs:1:9
+   |
+LL | #![deny(clippy::use_self)]
+   |         ^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error; 1 warning emitted
+

tests/ui-cargo/cargo_rust_version/fail_both_same/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "fail-both-same"
+version = "0.1.0"
+rust-version = "1.57.0"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tests/ui-cargo/cargo_rust_version/fail_both_same/clippy.toml

@@ -0,0 +1 @@
+msrv = "1.57"