More information for links conflicting

src/cargo/core/resolver/errors.rs

@@ -129,6 +129,10 @@ pub(super) fn activation_error(
                     msg.push_str(link);
                     msg.push_str("` as well:\n");
                     msg.push_str(&describe_path(&cx.parents.path_to_bottom(p)));
+                    msg.push_str("\nOnly one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. ");
+                    msg.push_str("Try to adjust your dependencies so that only one package uses the links ='");
+                    msg.push_str(&*dep.package_name());
+                    msg.push_str("' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.");
                 }
                 ConflictReason::MissingFeatures(features) => {
                     msg.push_str("\n\nthe package `");

tests/testsuite/build_script.rs

@@ -772,6 +772,7 @@ versions that meet the requirements `*` are: 0.5.0
 
 the package `a-sys` links to the native library `a`, but it conflicts with a previous package which links to `a` as well:
 package `foo v0.5.0 ([..])`
+Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links ='a-sys' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.
 
 failed to select a version for `a-sys` which could resolve this conflict
 ").run();
@@ -891,6 +892,7 @@ versions that meet the requirements `*` are: 0.5.0
 
 the package `a-sys` links to the native library `a`, but it conflicts with a previous package which links to `a` as well:
 package `foo v0.5.0 ([..])`
+Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links ='a-sys' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.
 
 failed to select a version for `a-sys` which could resolve this conflict
 ").run();
@@ -4081,6 +4083,7 @@ versions that meet the requirements `*` are: 0.5.0
 
 the package `a` links to the native library `a`, but it conflicts with a previous package which links to `a` as well:
 package `foo v0.5.0 ([..])`
+Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links ='a' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.
 
 failed to select a version for `a` which could resolve this conflict
 ").run();