Add support for IMPORTED GLOBAL targets to be aliased

Issue: #15569
Issue: #17197

Help/command/add_executable.rst

@@ -74,8 +74,9 @@ properties for more information.
 Creates an :ref:`Alias Target <Alias Targets>`, such that ``<name>`` can
 be used to refer to ``<target>`` in subsequent commands.  The ``<name>``
 does not appear in the generated buildsystem as a make target.  The
-``<target>`` may not be an :ref:`Imported Target <Imported Targets>` or an
-``ALIAS``.  ``ALIAS`` targets can be used as targets to read properties
+``<target>`` may not be a non-``GLOBAL``
+:ref:`Imported Target <Imported Targets>` or an ``ALIAS``.
+``ALIAS`` targets can be used as targets to read properties
 from, executables for custom commands and custom targets.  They can also be
 tested for existence with the regular :command:`if(TARGET)` subcommand.
 The ``<name>`` may not be used to modify properties of ``<target>``, that

Help/command/add_library.rst

@@ -125,7 +125,8 @@ Alias Libraries
 Creates an :ref:`Alias Target <Alias Targets>`, such that ``<name>`` can be
 used to refer to ``<target>`` in subsequent commands.  The ``<name>`` does
 not appear in the generated buildsystem as a make target.  The ``<target>``
-may not be an :ref:`Imported Target <Imported Targets>` or an ``ALIAS``.
+may not be a non-``GLOBAL`` :ref:`Imported Target <Imported Targets>` or an
+``ALIAS``.
 ``ALIAS`` targets can be used as linkable targets and as targets to
 read properties from.  They can also be tested for existence with the
 regular :command:`if(TARGET)` subcommand.  The ``<name>`` may not be used

Source/cmAddExecutableCommand.cxx

@@ -140,8 +140,7 @@ bool cmAddExecutableCommand::InitialPass(std::vector<std::string> const& args,
     if (!aliasedTarget) {
       std::ostringstream e;
       e << "cannot create ALIAS target \"" << exename << "\" because target \""
-        << aliasedName << "\" does not already "
-                          "exist.";
+        << aliasedName << "\" does not already exist.";
       this->SetError(e.str());
       return false;
     }
@@ -149,15 +148,15 @@ bool cmAddExecutableCommand::InitialPass(std::vector<std::string> const& args,
     if (type != cmStateEnums::EXECUTABLE) {
       std::ostringstream e;
       e << "cannot create ALIAS target \"" << exename << "\" because target \""
-        << aliasedName << "\" is not an "
-                          "executable.";
+        << aliasedName << "\" is not an executable.";
       this->SetError(e.str());
       return false;
     }
-    if (aliasedTarget->IsImported()) {
+    if (aliasedTarget->IsImported() &&
+        !aliasedTarget->IsImportedGloballyVisible()) {
       std::ostringstream e;
       e << "cannot create ALIAS target \"" << exename << "\" because target \""
-        << aliasedName << "\" is IMPORTED.";
+        << aliasedName << "\" is imported but not globally visible.";
       this->SetError(e.str());
       return false;
     }

Source/cmAddLibraryCommand.cxx

@@ -256,13 +256,6 @@ bool cmAddLibraryCommand::InitialPass(std::vector<std::string> const& args,
       this->SetError(e.str());
       return false;
     }
-    if (aliasedTarget->IsImported()) {
-      std::ostringstream e;
-      e << "cannot create ALIAS target \"" << libName << "\" because target \""
-        << aliasedName << "\" is IMPORTED.";
-      this->SetError(e.str());
-      return false;
-    }
     this->Makefile->AddAlias(libName, aliasedName);
     return true;
   }

Tests/RunCMake/alias_targets/RunCMakeTest.cmake

@@ -6,6 +6,7 @@ run_cmake(exclude-from-all)
 run_cmake(imported)
 run_cmake(invalid-name)
 run_cmake(invalid-target)
+run_cmake(imported-global-target)
 run_cmake(imported-target)
 run_cmake(alias-target)
 run_cmake(set_property)

Tests/RunCMake/alias_targets/imported-global-target-stderr.txt

@@ -0,0 +1,2 @@
+^'alias-test-exe' is an alias for 'test-exe' and its name-property contains 'test-exe'.
+'alias-test-lib' is an alias for 'test-lib' and its name-property contains 'test-lib'.$

Tests/RunCMake/alias_targets/imported-global-target.cmake

@@ -0,0 +1,46 @@
+
+enable_language(CXX)
+
+
+add_executable(test-exe IMPORTED GLOBAL)
+add_executable(alias-test-exe ALIAS test-exe)
+
+if(TARGET alias-test-exe)
+  get_target_property(aliased-target alias-test-exe ALIASED_TARGET)
+  if("${aliased-target}" STREQUAL "test-exe")
+    get_target_property(aliased-name alias-test-exe NAME)
+    if("${aliased-name}" STREQUAL "test-exe")
+      message("'alias-test-exe' is an alias for '${aliased-target}'"
+              " and its name-property contains '${aliased-name}'.")
+    else()
+      message("'alias-test-exe' is an alias for '${aliased-target}'"
+              " but its name-property contains '${aliased-name}'!?")
+    endif()
+  else()
+    message("'alias-test-exe' is something but not a real target!?")
+  endif()
+else()
+    message("'alias-test-exe' does not exist!?")
+endif()
+
+
+add_library(test-lib SHARED IMPORTED GLOBAL)
+add_library(alias-test-lib ALIAS test-lib)
+
+if(TARGET alias-test-lib)
+  get_target_property(aliased-target alias-test-lib ALIASED_TARGET)
+  if("${aliased-target}" STREQUAL "test-lib")
+    get_target_property(aliased-name alias-test-lib NAME)
+    if("${aliased-name}" STREQUAL "test-lib")
+      message("'alias-test-lib' is an alias for '${aliased-target}'"
+              " and its name-property contains '${aliased-name}'.")
+    else()
+      message("'alias-test-lib' is an alias for '${aliased-target}'"
+              " but its name-property contains '${aliased-name}'!?")
+    endif()
+  else()
+    message("'alias-test-lib' is something but not a real target!?")
+  endif()
+else()
+    message("'alias-test-lib' does not exist!?")
+endif()

Tests/RunCMake/alias_targets/imported-target-stderr.txt

@@ -1,5 +1,9 @@
-CMake Error at imported-target.cmake:6 \(add_library\):
-  add_library cannot create ALIAS target "alias" because target "foo" is
-  IMPORTED.
+^CMake Error at imported-target.cmake:[0-9]+ \(add_executable\):
+  add_executable cannot create ALIAS target \"alias-test-exe\" because target
+  \"test-exe\" is imported but not globally visible.
 Call Stack \(most recent call first\):
-  CMakeLists.txt:3 \(include\)
+  CMakeLists.txt:[0-9]+ \(include\)
+
+
+'alias-test-exe' does not exist![?]
+'alias-test-lib' does not exist![?]$

Tests/RunCMake/alias_targets/imported-target.cmake

@@ -1,6 +1,46 @@
 
 enable_language(CXX)
 
-add_library(foo SHARED IMPORTED)
 
-add_library(alias ALIAS foo)
+add_executable(test-exe IMPORTED)
+add_executable(alias-test-exe ALIAS test-exe)
+
+if(TARGET alias-test-exe)
+  get_target_property(aliased-target alias-test-exe ALIASED_TARGET)
+  if("${aliased-target}" STREQUAL "test-exe")
+    get_target_property(aliased-name alias-test-exe NAME)
+    if("${aliased-name}" STREQUAL "test-exe")
+      message("'alias-test-exe' is an alias for '${aliased-target}'"
+              " and its name-property contains '${aliased-name}'.")
+    else()
+      message("'alias-test-exe' is an alias for '${aliased-target}'"
+              " but its name-property contains '${aliased-name}'!?")
+    endif()
+  else()
+    message("'alias-test-exe' is something but not a real target!?")
+  endif()
+else()
+    message("'alias-test-exe' does not exist!?")
+endif()
+
+
+add_library(test-lib SHARED IMPORTED)
+add_library(alias-test-lib ALIAS test-lib)
+
+if(TARGET alias-test-lib)
+  get_target_property(aliased-target alias-test-lib ALIASED_TARGET)
+  if("${aliased-target}" STREQUAL "test-lib")
+    get_target_property(aliased-name alias-test-lib NAME)
+    if("${aliased-name}" STREQUAL "test-lib")
+      message("'alias-test-lib' is an alias for '${aliased-target}'"
+              " and its name-property contains '${aliased-name}'.")
+    else()
+      message("'alias-test-lib' is an alias for '${aliased-target}'"
+              " but its name-property contains '${aliased-name}'!?")
+    endif()
+  else()
+    message("'alias-test-lib' is something but not a real target!?")
+  endif()
+else()
+    message("'alias-test-lib' does not exist!?")
+endif()