fix(toml): Simplify [project] warning

Author: epage

src/cargo/util/toml/mod.rs

@@ -1027,22 +1027,8 @@ fn to_real_manifest(
         )));
     }
 
-    match (&original_toml.package, &original_toml.project) {
-        (Some(_), Some(_)) => {
-            warnings.push(format!(
-                "manifest at `{}` contains both `project` and `package`, \
-                    this could become a hard error in the future",
-                package_root.display()
-            ));
-        }
-        (None, Some(_)) => {
-            warnings.push(format!(
-                "manifest at `{}` contains `[project]` instead of `[package]`, \
-                                this could become a hard error in the future",
-                package_root.display()
-            ));
-        }
-        (Some(_), None) | (None, None) => {}
+    if original_toml.project.is_some() {
+        warnings.push(format!("`[project]` is deprecated in favor of `[package]`"));
     }
 
     if resolved_package.metabuild.is_some() {

tests/testsuite/check.rs

@@ -1002,7 +1002,7 @@ fn warn_manifest_package_and_project() {
     p.cargo("check")
         .with_stderr(
             "\
-[WARNING] manifest at `[CWD]` contains both `project` and `package`, this could become a hard error in the future
+[WARNING] `[project]` is deprecated in favor of `[package]`
 [CHECKING] foo v0.0.1 ([CWD])
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
 ",
@@ -1083,7 +1083,7 @@ fn warn_manifest_with_project() {
     p.cargo("check")
         .with_stderr(
             "\
-[WARNING] manifest at `[CWD]` contains `[project]` instead of `[package]`, this could become a hard error in the future
+[WARNING] `[project]` is deprecated in favor of `[package]`
 [CHECKING] foo v0.0.1 ([CWD])
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
 ",