Merge topic 'allow-fallback-config-mapping'

587ab322 Tests: Add test for MAP_IMPORTED_CONFIG_<CONFIG> empty fallback
149d49ea Teach MAP_IMPORTED_CONFIG_<CONFIG> to support configuration-less import
60d73393 Help: Format MAP_IMPORTED_CONFIG_<CONFIG> documentation

Help/prop_tgt/MAP_IMPORTED_CONFIG_CONFIG.rst

 MAP_IMPORTED_CONFIG_<CONFIG>
 ----------------------------
 
-Map from project configuration to IMPORTED target's configuration.
+Map from project configuration to
+:ref:`imported target <IMPORTED targets>`'s configuration.
 
 Set this to the list of configurations of an imported target that may
-be used for the current project's <CONFIG> configuration.  Targets
+be used for the current project's ``<CONFIG>`` configuration.  Targets
 imported from another project may not provide the same set of
 configuration names available in the current project.  Setting this
 property tells CMake what imported configurations are suitable for use
-when building the <CONFIG> configuration.  The first configuration in
-the list found to be provided by the imported target is selected.  If
-this property is set and no matching configurations are available,
+when building the ``<CONFIG>`` configuration.  The first configuration in
+the list found to be provided by the imported target (i.e. via
+:prop_tgt:`IMPORTED_LOCATION_<CONFIG>` for the mapped-to ``<CONFIG>``)
+is selected.  As a special case, an empty list element refers to the
+configuration-less imported target location
+(i.e. :prop_tgt:`IMPORTED_LOCATION`).
+
+If this property is set and no matching configurations are available,
 then the imported target is considered to be not found.  This property
 is ignored for non-imported targets.
 
-This property is initialized by the value of the variable
-CMAKE_MAP_IMPORTED_CONFIG_<CONFIG> if it is set when a target is
-created.
+This property is initialized by the value of the
+:variable:`CMAKE_MAP_IMPORTED_CONFIG_<CONFIG>` variable if it is set when a
+target is created.

Help/release/dev/allow-fallback-config-mapping.rst

+allow-fallback-config-mapping
+-----------------------------
+
+* The :prop_tgt:`MAP_IMPORTED_CONFIG_<CONFIG>` target property learned
+  to interpret empty list elements as referring to the configuration-less
+  imported location specified by :prop_tgt:`IMPORTED_LOCATION`.

Source/cmTarget.cxx

@@ -1403,7 +1403,7 @@ bool cmTarget::GetMappedConfig(std::string const& desired_config,
     std::string mapProp = "MAP_IMPORTED_CONFIG_";
     mapProp += desired_config;
     if (const char* mapValue = this->GetProperty(mapProp)) {
-      cmSystemTools::ExpandListArgument(mapValue, mappedConfigs);
+      cmSystemTools::ExpandListArgument(mapValue, mappedConfigs, true);
     }
   }
 
@@ -1416,20 +1416,33 @@ bool cmTarget::GetMappedConfig(std::string const& desired_config,
   for (std::vector<std::string>::const_iterator mci = mappedConfigs.begin();
        !*loc && !*imp && mci != mappedConfigs.end(); ++mci) {
     // Look for this configuration.
-    std::string mcUpper = cmSystemTools::UpperCase(*mci);
-    std::string locProp = "IMPORTED_LOCATION_";
-    locProp += mcUpper;
-    *loc = this->GetProperty(locProp);
-    if (allowImp) {
-      std::string impProp = "IMPORTED_IMPLIB_";
-      impProp += mcUpper;
-      *imp = this->GetProperty(impProp);
-    }
+    if (mci->empty()) {
+      // An empty string in the mapping has a special meaning:
+      // look up the config-less properties.
+      *loc = this->GetProperty("IMPORTED_LOCATION");
+      if (allowImp) {
+        *imp = this->GetProperty("IMPORTED_IMPLIB");
+      }
+      // If it was found, set the suffix.
+      if (*loc || *imp) {
+        suffix = "";
+      }
+    } else {
+      std::string mcUpper = cmSystemTools::UpperCase(*mci);
+      std::string locProp = "IMPORTED_LOCATION_";
+      locProp += mcUpper;
+      *loc = this->GetProperty(locProp);
+      if (allowImp) {
+        std::string impProp = "IMPORTED_IMPLIB_";
+        impProp += mcUpper;
+        *imp = this->GetProperty(impProp);
+      }
 
-    // If it was found, use it for all properties below.
-    if (*loc || *imp) {
-      suffix = "_";
-      suffix += mcUpper;
+      // If it was found, use it for all properties below.
+      if (*loc || *imp) {
+        suffix = "_";
+        suffix += mcUpper;
+      }
     }
   }
 

Tests/GeneratorExpression/CMakeLists.txt

@@ -171,6 +171,13 @@ add_executable(Alias::SomeExe ALIAS someexe)
 
 add_library(Alias::SomeLib ALIAS empty1)
 
+add_library(importedFallback STATIC IMPORTED)
+set_property(TARGET importedFallback PROPERTY IMPORTED_LOCATION_DEBUG debug_loc)
+set_property(TARGET importedFallback PROPERTY IMPORTED_LOCATION_RELEASE release_loc)
+set_property(TARGET importedFallback PROPERTY IMPORTED_LOCATION fallback_loc)
+set_property(TARGET importedFallback PROPERTY MAP_IMPORTED_CONFIG_DEBUG "" DEBUG)
+set_property(TARGET importedFallback PROPERTY MAP_IMPORTED_CONFIG_RELEASE "")
+
 add_custom_target(check-part3 ALL
   COMMAND ${CMAKE_COMMAND}
     -Dtest_version_greater_1=$<VERSION_GREATER:1.0,1.1.1>
@@ -184,6 +191,7 @@ add_custom_target(check-part3 ALL
     -Dtest_imported_release=$<TARGET_PROPERTY:imported4,INCLUDE_DIRECTORIES>
     -Dtest_imported_relwithdebinfo=$<TARGET_PROPERTY:imported4,INCLUDE_DIRECTORIES>
     -Dtest_imported_minsizerel=$<TARGET_PROPERTY:imported4,INCLUDE_DIRECTORIES>
+    -Dtest_imported_fallback=$<STREQUAL:$<TARGET_FILE_NAME:importedFallback>,fallback_loc>
     -Dtest_alias_file_exe=$<STREQUAL:$<TARGET_FILE:Alias::SomeExe>,$<TARGET_FILE:someexe>>
     -Dtest_alias_file_lib=$<STREQUAL:$<TARGET_FILE:Alias::SomeLib>,$<TARGET_FILE:empty1>>
     -Dtest_alias_target_name=$<STREQUAL:$<TARGET_PROPERTY:Alias::SomeLib,NAME>,$<TARGET_PROPERTY:empty1,NAME>>

Tests/GeneratorExpression/check-part3.cmake

@@ -21,6 +21,8 @@ foreach(c debug release relwithdebinfo minsizerel)
   endif()
 endforeach()
 
+check(test_imported_fallback "1")
+
 check(test_alias_file_exe "1")
 check(test_alias_file_lib "1")
 check(test_alias_target_name "1")