This time for sure: stop using --undefined dynamic_lookup in osx linking.

For the time being, all C++ links will provide ObjC core libraries on the command line,
via having the link actions imply 'contains_objc_sources', which is a built-in feature
that is in the process of being enabled automatically when objective-C/C++ sources
are involved in the build. Once that happens, the 'imply' directives will be removed.

RELNOTES: Stop using --undefined dynamic_lookup in Apple links. Enables unresolved symbol errors.
PiperOrigin-RevId: 169437020

2 files changed, 235 insertions, 115 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/packages/util/MOCK_OSX_CROSSTOOL b/src/test/java/com/google/devtools/build/lib/packages/util/MOCK_OSX_CROSSTOOL
index 451a178747..7aedc55922 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/util/MOCK_OSX_CROSSTOOL
+++ b/src/test/java/com/google/devtools/build/lib/packages/util/MOCK_OSX_CROSSTOOL
@@ -137,9 +137,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -1121,8 +1118,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -1867,6 +1862,8 @@ toolchain {
   }
   linking_mode_flags {
     mode: DYNAMIC
+    linker_flag: "-undefined"
+    linker_flag: "dynamic_lookup"
   }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
@@ -2849,8 +2846,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -3593,9 +3588,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -4577,8 +4569,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -5321,9 +5311,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -6305,8 +6292,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -7051,9 +7036,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -8037,8 +8019,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -8789,9 +8769,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -9777,8 +9754,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -10530,9 +10505,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -11517,8 +11489,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "x86_64-apple-tvos"
       }
@@ -11528,8 +11498,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "x86_64-apple-tvos"
       }
@@ -12301,9 +12269,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -13287,8 +13252,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -14039,9 +14002,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -15025,8 +14985,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -15797,9 +15755,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -16785,8 +16740,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
@@ -17558,9 +17511,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -18545,8 +18495,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "arm64-apple-tvos"
       }
@@ -18556,8 +18504,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "arm64-apple-tvos"
       }
@@ -19349,9 +19295,6 @@ toolchain {
     compiler_flag: "-g"
     compiler_flag: "-DDEBUG"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -20335,8 +20278,6 @@ toolchain {
       action: "c++-link-executable"
       action: "c++-link-dynamic-library"
       flag_group {
-        flag: "-undefined"
-        flag: "dynamic_lookup"
       }
     }
   }
diff --git a/tools/osx/crosstool/CROSSTOOL.tpl b/tools/osx/crosstool/CROSSTOOL.tpl
index 8abffa5cd7..e2193ddbe5 100644
--- a/tools/osx/crosstool/CROSSTOOL.tpl
+++ b/tools/osx/crosstool/CROSSTOOL.tpl
@@ -118,9 +118,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   objcopy_embed_flag: "-I"
   objcopy_embed_flag: "binary"
@@ -144,6 +143,8 @@ toolchain {
   }
   linking_mode_flags {
     mode: DYNAMIC
+    linker_flag: "-undefined"
+    linker_flag: "dynamic_lookup"
   }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
@@ -205,6 +206,17 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -1505,6 +1517,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -1526,6 +1539,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -1604,6 +1618,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -1704,9 +1719,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "x86_64-apple-ios"
@@ -1730,9 +1744,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -1795,6 +1806,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -3102,6 +3133,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -3123,6 +3155,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -3201,6 +3234,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -3301,9 +3335,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "i386-apple-ios"
@@ -3327,9 +3360,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -3392,6 +3422,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -4701,6 +4751,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -4722,6 +4773,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -4800,6 +4852,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -4900,9 +4953,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "x86_64-apple-tvos"
@@ -4927,9 +4979,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -4992,6 +5041,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -5831,8 +5900,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "x86_64-apple-tvos"
       }
@@ -6329,6 +6396,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -6351,6 +6419,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -6430,6 +6499,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -6530,9 +6600,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "i386-apple-ios"
@@ -6556,9 +6625,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -6621,6 +6687,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -7928,6 +8014,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -7949,6 +8036,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -8027,6 +8115,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -8127,9 +8216,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "armv7-apple-ios"
@@ -8153,9 +8241,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -8218,6 +8303,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -9513,6 +9618,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -9534,6 +9640,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -9612,6 +9719,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -9712,9 +9820,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "armv7-apple-watchos"
@@ -9738,9 +9845,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -9803,6 +9907,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -11100,6 +11224,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -11121,6 +11246,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -11199,6 +11325,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -11299,9 +11426,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "arm64-apple-tvos"
@@ -11326,9 +11452,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -11391,6 +11514,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -12230,8 +12373,6 @@ toolchain {
       action: "c++-link-dynamic-library"
       flag_group {
         flag: "-lc++"
-        flag: "-undefined"
-        flag: "dynamic_lookup"
         flag: "-target"
         flag: "arm64-apple-tvos"
       }
@@ -12716,6 +12857,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -12738,6 +12880,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -12817,6 +12960,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -12917,9 +13061,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   linker_flag: "-target"
   linker_flag: "arm64-apple-ios"
@@ -12943,9 +13086,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -13008,6 +13148,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -14303,6 +14463,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -14324,6 +14485,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -14402,6 +14564,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }
@@ -14503,9 +14666,8 @@ toolchain {
   compiler_flag: "-Wself-assign"
   compiler_flag: "-fno-omit-frame-pointer"
   cxx_flag: "-std=c++11"
-  linker_flag: "-undefined"
-  linker_flag: "dynamic_lookup"
   linker_flag: "-headerpad_max_install_names"
+  linker_flag: "-lc++"
   linker_flag: "-no-canonical-prefixes"
   objcopy_embed_flag: "-I"
   objcopy_embed_flag: "binary"
@@ -14528,12 +14690,6 @@ toolchain {
     mode: DBG
     compiler_flag: "-g"
   }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
-  linking_mode_flags {
-    mode: DYNAMIC
-  }
   make_variable {
     name: "STACK_FRAME_UNLIMITED"
     value: "-Wframe-larger-than=100000000 -Wno-vla"
@@ -14599,6 +14755,26 @@ toolchain {
     }
   }
   feature {
+    name: "contains_objc_source"
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-fobjc-link-runtime"
+      }
+    }
+    flag_set {
+      action: "c++-link-interface-dynamic-library"
+      action: "c++-link-dynamic-library"
+      action: "c++-link-executable"
+      flag_group {
+        flag: "-framework"
+        flag: "UIKit"
+      }
+    }
+  }
+  feature {
     name: "objc_actions"
     implies: "objc-compile"
     implies: "objc++-compile"
@@ -15894,6 +16070,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "symbol_counts"
     implies: "linkstamps"
     implies: "output_execpath_flags_executable"
@@ -15915,6 +16092,7 @@ toolchain {
       tool_path: "cc_wrapper.sh"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "has_configured_linker_path"
     implies: "symbol_counts"
     implies: "shared_flag"
@@ -15993,6 +16171,7 @@ toolchain {
       tool_path: "wrapped_clang"
       execution_requirement: "requires-darwin"
     }
+    implies: "contains_objc_source"
     implies: "strip_debug_symbols"
     implies: "apple_env"
   }