Move --linkopt flags into user_link_flags

Previous behavior was to put flags coming from Bazel option --linkopt into
legacy_link_flags. They should be in user_link_flags instead (together with
flags coming from linkopts rule attribute). This cl introduces
--experimental_linkopts_in_user_link_flags option that flips the behavior.

There is another incompatible change. Previously cc_common.create_link_variables() included flags from --linkopt, with the flag flipped it doesn't anymore. I believe
--linkopt flags shouldn't be there by default because:
* We don't tie the API with the specifics of C++ rules/options, enabling theoretical use with other languages (objc)
* Users are free to use ctx.fragments.cpp to access C++ options and add them explicitly (https://github.com/bazelbuild/bazel/issues/5602)
* New behavior maintains the symmetry with --copt and user_compile_flags

RELNOTES: None.
PiperOrigin-RevId: 205274272

1 files changed, 48 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/LinkBuildVariablesTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/LinkBuildVariablesTest.java
index cabbb2da82..cffef0494c 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/LinkBuildVariablesTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/LinkBuildVariablesTest.java
@@ -16,6 +16,7 @@ package com.google.devtools.build.lib.rules.cpp;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.Action;
 import com.google.devtools.build.lib.actions.Artifact;
@@ -367,4 +368,51 @@ public class LinkBuildVariablesTest extends LinkBuildVariablesTestCase {
     }
     return null;
   }
+
+  @Test
+  public void testUserLinkFlags() throws Exception {
+    useConfiguration("--linkopt=-bar", "--noexperimental_linkopts_in_user_link_flags");
+
+    scratch.file("x/BUILD", "cc_binary(name = 'foo', srcs = ['a.cc'], linkopts = ['-foo'])");
+    scratch.file("x/a.cc");
+
+    ConfiguredTarget testTarget = getConfiguredTarget("//x:foo");
+    CcToolchainVariables testVariables =
+        getLinkBuildVariables(testTarget, LinkTargetType.EXECUTABLE);
+
+    ImmutableList<String> userLinkFlags =
+        CcToolchainVariables.toStringList(
+            testVariables, LinkBuildVariables.USER_LINK_FLAGS.getVariableName());
+    assertThat(userLinkFlags).contains("-foo");
+    assertThat(userLinkFlags).doesNotContain("-bar");
+
+    ImmutableList<String> legacyLinkFlags =
+        CcToolchainVariables.toStringList(
+            testVariables, LinkBuildVariables.LEGACY_LINK_FLAGS.getVariableName());
+    assertThat(legacyLinkFlags).doesNotContain("-foo");
+    assertThat(legacyLinkFlags).contains("-bar");
+  }
+
+  @Test
+  public void testUserLinkFlagsWithLinkoptOption() throws Exception {
+    useConfiguration("--linkopt=-bar", "--experimental_linkopts_in_user_link_flags");
+
+    scratch.file("x/BUILD", "cc_binary(name = 'foo', srcs = ['a.cc'], linkopts = ['-foo'])");
+    scratch.file("x/a.cc");
+
+    ConfiguredTarget testTarget = getConfiguredTarget("//x:foo");
+    CcToolchainVariables testVariables =
+        getLinkBuildVariables(testTarget, LinkTargetType.EXECUTABLE);
+
+    ImmutableList<String> userLinkFlags =
+        CcToolchainVariables.toStringList(
+            testVariables, LinkBuildVariables.USER_LINK_FLAGS.getVariableName());
+    assertThat(userLinkFlags).containsAllOf("-foo", "-bar").inOrder();
+
+    ImmutableList<String> legacyLinkFlags =
+        CcToolchainVariables.toStringList(
+            testVariables, LinkBuildVariables.LEGACY_LINK_FLAGS.getVariableName());
+    assertThat(legacyLinkFlags).doesNotContain("-foo");
+    assertThat(legacyLinkFlags).doesNotContain("-bar");
+  }
 }