Warn only when lto is open and add test

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

src/cargo/core/compiler/lto.rs

@@ -106,18 +106,21 @@ fn calculate(
     };
     // LTO can only be performed if *all* of the crate types support it.
     // For example, a cdylib/rlib combination won't allow LTO.
-    let can_not_lto_types = crate_types
+    let not_lto_types = crate_types
         .iter()
         .filter(|ct| !ct.can_lto())
         .map(|ct| ct.as_str())
         .collect::<Vec<_>>();
-    let all_lto_types = can_not_lto_types.len() == 0;
+    let all_lto_types = not_lto_types.len() == 0;
     if !all_lto_types {
-        bcx.config.shell().warn(format!(
-            "LTO can only be performed if all of the crate types support it,\
-             you have some crate types do not support LTO: {}",
-            can_not_lto_types.join(","),
-        ))?;
+        if let profiles::Lto::Named(_) | profiles::Lto::Bool(_) = unit.profile.lto {
+            bcx.config.shell().warn(format!(
+                "LTO can only be performed if all of the crate types support it, \
+                 package `{}` have some crate types do not support LTO: {}",
+                unit.pkg.name(),
+                not_lto_types.join(","),
+            ))?;
+        }
     }
     // Compute the LTO based on the profile, and what our parent requires.
     let lto = if unit.target.for_host() {

tests/testsuite/lto.rs

@@ -624,6 +624,25 @@ fn dylib() {
         .run();
 }
 
+#[cargo_test]
+fn lto_with_unsupported_crate_types() {
+    let p = project_with_dep("'dylib','rlib'");
+    p.cargo("build --release -v")
+        .with_stderr_contains(
+            "\
+[WARNING] LTO can only be performed if all of the crate types support it, \
+package `bar` have some crate types do not support LTO: dylib,rlib
+[WARNING] LTO can only be performed if all of the crate types support it, \
+package `registry` have some crate types do not support LTO: lib
+[WARNING] LTO can only be performed if all of the crate types support it, \
+package `registry-shared` have some crate types do not support LTO: lib
+[WARNING] LTO can only be performed if all of the crate types support it, \
+package `registry-shared` have some crate types do not support LTO: lib
+",
+        )
+        .run();
+}
+
 #[cargo_test]
 fn test_profile() {
     Package::new("bar", "0.0.1")