Allow export of targets with INTERFACE_SOURCES.

Use the same rules for paths in source and binary dirs in
installed INTERFACE_SOURCES as are used for
INTERFACE_INCLUDE_DIRECTORIES.

Help/command/target_sources.rst

@@ -22,10 +22,6 @@ items will populate the :prop_tgt:`SOURCES` property of
 following arguments specify sources.  Repeated calls for the same
 ``<target>`` append items in the order called.
 
-Targets with :prop_tgt:`INTERFACE_SOURCES` may not be exported with the
-:command:`export` or :command:`install(EXPORT)` commands. This limitation may be
-lifted in a future version of CMake.
-
 Arguments to ``target_sources`` may use "generator expressions"
 with the syntax ``$<...>``. See the :manual:`cmake-generator-expressions(7)`
 manual for available expressions.  See the :manual:`cmake-buildsystem(7)`

Help/prop_tgt/INTERFACE_SOURCES.rst

@@ -12,10 +12,6 @@ When target dependencies are specified using :command:`target_link_libraries`,
 CMake will read this property from all target dependencies to determine the
 sources of the consumer.
 
-Targets with ``INTERFACE_SOURCES`` may not be exported with the
-:command:`export` or :command:`install(EXPORT)` commands. This limitation may be
-lifted in a future version of CMake.
-
 Contents of ``INTERFACE_SOURCES`` may use "generator expressions"
 with the syntax ``$<...>``.  See the :manual:`cmake-generator-expressions(7)`
 manual for available expressions.  See the :manual:`cmake-buildsystem(7)`

Source/cmExportBuildFileGenerator.cxx

@@ -68,16 +68,6 @@ bool cmExportBuildFileGenerator::GenerateMainFile(std::ostream& os)
       tei != this->Exports.end(); ++tei)
     {
     cmTarget* te = *tei;
-    if (te->GetProperty("INTERFACE_SOURCES"))
-      {
-      std::ostringstream e;
-      e << "Target \""
-        << te->GetName()
-        << "\" has a populated INTERFACE_SOURCES property.  This is not "
-          "currently supported.";
-      cmSystemTools::Error(e.str().c_str());
-      return false;
-      }
     this->GenerateImportTargetCode(os, te);
 
     te->AppendBuildInterfaceIncludes();
@@ -87,6 +77,9 @@ bool cmExportBuildFileGenerator::GenerateMainFile(std::ostream& os)
     this->PopulateInterfaceProperty("INTERFACE_INCLUDE_DIRECTORIES", te,
                                     cmGeneratorExpression::BuildInterface,
                                     properties, missingTargets);
+    this->PopulateInterfaceProperty("INTERFACE_SOURCES", te,
+                                    cmGeneratorExpression::BuildInterface,
+                                    properties, missingTargets);
     this->PopulateInterfaceProperty("INTERFACE_COMPILE_DEFINITIONS", te,
                                     cmGeneratorExpression::BuildInterface,
                                     properties, missingTargets);

Source/cmExportFileGenerator.cxx

@@ -224,7 +224,7 @@ static bool isSubDirectory(const char* a, const char* b)
 
 //----------------------------------------------------------------------------
 static bool checkInterfaceDirs(const std::string &prepro,
-                      cmTarget *target)
+                      cmTarget *target, const std::string& prop)
 {
   const char* installDir =
             target->GetMakefile()->GetSafeDefinition("CMAKE_INSTALL_PREFIX");
@@ -250,20 +250,27 @@ static bool checkInterfaceDirs(const std::string &prepro,
     std::ostringstream e;
     if (genexPos != std::string::npos)
       {
-      switch (target->GetPolicyStatusCMP0041())
+      if (prop == "INTERFACE_INCLUDE_DIRECTORIES")
         {
-        case cmPolicies::WARN:
-          messageType = cmake::WARNING;
-          e << target->GetMakefile()->GetPolicies()
-                      ->GetPolicyWarning(cmPolicies::CMP0041) << "\n";
-          break;
-        case cmPolicies::OLD:
-          continue;
-        case cmPolicies::REQUIRED_IF_USED:
-        case cmPolicies::REQUIRED_ALWAYS:
-        case cmPolicies::NEW:
-          hadFatalError = true;
-          break; // Issue fatal message.
+        switch (target->GetPolicyStatusCMP0041())
+          {
+          case cmPolicies::WARN:
+            messageType = cmake::WARNING;
+            e << target->GetMakefile()->GetPolicies()
+                        ->GetPolicyWarning(cmPolicies::CMP0041) << "\n";
+            break;
+          case cmPolicies::OLD:
+            continue;
+          case cmPolicies::REQUIRED_IF_USED:
+          case cmPolicies::REQUIRED_ALWAYS:
+          case cmPolicies::NEW:
+            hadFatalError = true;
+            break; // Issue fatal message.
+          }
+        }
+      else
+        {
+        hadFatalError = true;
         }
       }
     if (cmHasLiteralPrefix(li->c_str(), "${_IMPORT_PREFIX}"))
@@ -272,8 +279,8 @@ static bool checkInterfaceDirs(const std::string &prepro,
       }
     if (!cmSystemTools::FileIsFullPath(li->c_str()))
       {
-      e << "Target \"" << target->GetName() << "\" "
-           "INTERFACE_INCLUDE_DIRECTORIES property contains relative path:\n"
+      e << "Target \"" << target->GetName() << "\" " << prop <<
+           " property contains relative path:\n"
            "  \"" << *li << "\"";
       target->GetMakefile()->IssueMessage(messageType, e.str());
       }
@@ -289,32 +296,35 @@ static bool checkInterfaceDirs(const std::string &prepro,
         (!inBinary || isSubDirectory(installDir, topBinaryDir)) &&
         (!inSource || isSubDirectory(installDir, topSourceDir));
 
-      if (!shouldContinue)
+      if (prop == "INTERFACE_INCLUDE_DIRECTORIES")
         {
-        switch(target->GetPolicyStatusCMP0052())
+        if (!shouldContinue)
           {
-          case cmPolicies::WARN:
+          switch(target->GetPolicyStatusCMP0052())
             {
-            std::ostringstream s;
-            s << target->GetMakefile()->GetPolicies()
-                      ->GetPolicyWarning(cmPolicies::CMP0052) << "\n";
-            s << "Directory:\n    \"" << *li << "\"\nin "
-              "INTERFACE_INCLUDE_DIRECTORIES of target \""
-              << target->GetName() << "\" is a subdirectory of the install "
-              "directory:\n    \"" << installDir << "\"\nhowever it is also "
-              "a subdirectory of the " << (inBinary ? "build" : "source")
-              << " tree:\n    \"" << (inBinary ? topBinaryDir : topSourceDir)
-              << "\"" << std::endl;
-            target->GetMakefile()->IssueMessage(cmake::AUTHOR_WARNING,
-                                                s.str());
+            case cmPolicies::WARN:
+              {
+              std::ostringstream s;
+              s << target->GetMakefile()->GetPolicies()
+                        ->GetPolicyWarning(cmPolicies::CMP0052) << "\n";
+              s << "Directory:\n    \"" << *li << "\"\nin "
+                "INTERFACE_INCLUDE_DIRECTORIES of target \""
+                << target->GetName() << "\" is a subdirectory of the install "
+                "directory:\n    \"" << installDir << "\"\nhowever it is also "
+                "a subdirectory of the " << (inBinary ? "build" : "source")
+                << " tree:\n    \"" << (inBinary ? topBinaryDir : topSourceDir)
+                << "\"" << std::endl;
+              target->GetMakefile()->IssueMessage(cmake::AUTHOR_WARNING,
+                                                  s.str());
+              }
+            case cmPolicies::OLD:
+              shouldContinue = true;
+              break;
+            case cmPolicies::REQUIRED_ALWAYS:
+            case cmPolicies::REQUIRED_IF_USED:
+            case cmPolicies::NEW:
+              break;
             }
-          case cmPolicies::OLD:
-            shouldContinue = true;
-            break;
-          case cmPolicies::REQUIRED_ALWAYS:
-          case cmPolicies::REQUIRED_IF_USED:
-          case cmPolicies::NEW:
-            break;
           }
         }
       if (shouldContinue)
@@ -324,8 +334,8 @@ static bool checkInterfaceDirs(const std::string &prepro,
       }
     if (inBinary)
       {
-      e << "Target \"" << target->GetName() << "\" "
-           "INTERFACE_INCLUDE_DIRECTORIES property contains path:\n"
+      e << "Target \"" << target->GetName() << "\" " << prop <<
+           " property contains path:\n"
            "  \"" << *li << "\"\nwhich is prefixed in the build directory.";
       target->GetMakefile()->IssueMessage(messageType, e.str());
       }
@@ -333,8 +343,8 @@ static bool checkInterfaceDirs(const std::string &prepro,
       {
       if (inSource)
         {
-        e << "Target \"" << target->GetName() << "\" "
-            "INTERFACE_INCLUDE_DIRECTORIES property contains path:\n"
+        e << "Target \"" << target->GetName() << "\" " << prop <<
+            " property contains path:\n"
             "  \"" << *li << "\"\nwhich is prefixed in the source directory.";
         target->GetMakefile()->IssueMessage(messageType, e.str());
         }
@@ -364,6 +374,46 @@ static void prefixItems(std::string &exportDirs)
     }
 }
 
+//----------------------------------------------------------------------------
+void cmExportFileGenerator::PopulateSourcesInterface(
+                      cmTargetExport *tei,
+                      cmGeneratorExpression::PreprocessContext preprocessRule,
+                      ImportPropertyMap &properties,
+                      std::vector<std::string> &missingTargets)
+{
+  cmTarget *target = tei->Target;
+  assert(preprocessRule == cmGeneratorExpression::InstallInterface);
+
+  const char *propName = "INTERFACE_SOURCES";
+  const char *input = target->GetProperty(propName);
+
+  if (!input)
+    {
+    return;
+    }
+
+  if (!*input)
+    {
+    properties[propName] = "";
+    return;
+    }
+
+  std::string prepro = cmGeneratorExpression::Preprocess(input,
+                                                         preprocessRule,
+                                                         true);
+  if (!prepro.empty())
+    {
+    this->ResolveTargetsInGeneratorExpressions(prepro, target,
+                                                missingTargets);
+
+    if (!checkInterfaceDirs(prepro, target, propName))
+      {
+      return;
+      }
+    properties[propName] = prepro;
+    }
+}
+
 //----------------------------------------------------------------------------
 void cmExportFileGenerator::PopulateIncludeDirectoriesInterface(
                       cmTargetExport *tei,
@@ -424,7 +474,7 @@ void cmExportFileGenerator::PopulateIncludeDirectoriesInterface(
     this->ResolveTargetsInGeneratorExpressions(prepro, target,
                                                 missingTargets);
 
-    if (!checkInterfaceDirs(prepro, target))
+    if (!checkInterfaceDirs(prepro, target, propName))
       {
       return;
       }

Source/cmExportFileGenerator.h

@@ -139,6 +139,11 @@ protected:
                       cmGeneratorExpression::PreprocessContext preprocessRule,
                       ImportPropertyMap &properties,
                       std::vector<std::string> &missingTargets);
+  void PopulateSourcesInterface(
+                      cmTargetExport *target,
+                      cmGeneratorExpression::PreprocessContext preprocessRule,
+                      ImportPropertyMap &properties,
+                      std::vector<std::string> &missingTargets);
 
   void SetImportLinkInterface(const std::string& config,
                     std::string const& suffix,

Source/cmExportInstallFileGenerator.cxx

@@ -123,6 +123,7 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
 
   bool require2_8_12 = false;
   bool require3_0_0 = false;
+  bool require3_1_0 = false;
   bool requiresConfigFiles = false;
   // Create all the imported targets.
   for(std::vector<cmTargetExport*>::const_iterator
@@ -131,17 +132,6 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
     {
     cmTarget* te = (*tei)->Target;
 
-    if (te->GetProperty("INTERFACE_SOURCES"))
-      {
-      std::ostringstream e;
-      e << "Target \""
-        << te->GetName()
-        << "\" has a populated INTERFACE_SOURCES property.  This is not "
-          "currently supported.";
-      cmSystemTools::Error(e.str().c_str());
-      return false;
-      }
-
     requiresConfigFiles = requiresConfigFiles
                               || te->GetType() != cmTarget::INTERFACE_LIBRARY;
 
@@ -152,6 +142,9 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
     this->PopulateIncludeDirectoriesInterface(*tei,
                                   cmGeneratorExpression::InstallInterface,
                                   properties, missingTargets);
+    this->PopulateSourcesInterface(*tei,
+                                  cmGeneratorExpression::InstallInterface,
+                                  properties, missingTargets);
     this->PopulateInterfaceProperty("INTERFACE_SYSTEM_INCLUDE_DIRECTORIES",
                                   te,
                                   cmGeneratorExpression::InstallInterface,
@@ -190,6 +183,13 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
       {
       require3_0_0 = true;
       }
+    if(te->GetProperty("INTERFACE_SOURCES"))
+      {
+      // We can only generate INTERFACE_SOURCES in CMake 3.3, but CMake 3.1
+      // can consume them.
+      require3_1_0 = true;
+      }
+
     this->PopulateInterfaceProperty("INTERFACE_POSITION_INDEPENDENT_CODE",
                                   te, properties);
     this->PopulateCompatibleInterfaceProperties(te, properties);
@@ -197,7 +197,11 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
     this->GenerateInterfaceProperties(te, os, properties);
     }
 
-  if (require3_0_0)
+  if (require3_1_0)
+    {
+    this->GenerateRequiredCMakeVersion(os, "3.1.0");
+    }
+  else if (require3_0_0)
     {
     this->GenerateRequiredCMakeVersion(os, "3.0.0");
     }

Tests/ExportImport/Export/Interface/CMakeLists.txt

@@ -29,7 +29,17 @@ target_compile_features(use_auto_type INTERFACE cxx_auto_type)
 add_library(use_c_restrict INTERFACE)
 target_compile_features(use_c_restrict INTERFACE c_restrict)
 
-install(TARGETS headeronly sharediface use_auto_type use_c_restrict
+add_library(source_target INTERFACE)
+target_sources(source_target INTERFACE
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/source_target.cpp>
+  $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/src/source_target_for_install.cpp>
+)
+install(FILES
+  source_target_for_install.cpp
+  DESTINATION src
+)
+
+install(TARGETS headeronly sharediface use_auto_type use_c_restrict source_target
   EXPORT expInterface
 )
 install(TARGETS sharedlib

Tests/ExportImport/Export/Interface/source_target.cpp

@@ -0,0 +1,13 @@
+
+#ifndef USE_FROM_BUILD_DIR
+#error Expected define USE_FROM_BUILD_DIR
+#endif
+
+#ifdef USE_FROM_INSTALL_DIR
+#error Unexpected define USE_FROM_INSTALL_DIR
+#endif
+
+int source_symbol()
+{
+  return 42;
+}

Tests/ExportImport/Export/Interface/source_target_for_install.cpp

@@ -0,0 +1,13 @@
+
+#ifdef USE_FROM_BUILD_DIR
+#error Unexpected define USE_FROM_BUILD_DIR
+#endif
+
+#ifndef USE_FROM_INSTALL_DIR
+#error Expected define USE_FROM_INSTALL_DIR
+#endif
+
+int source_symbol()
+{
+  return 42;
+}

Tests/ExportImport/Import/Interface/CMakeLists.txt

@@ -82,6 +82,14 @@ endmacro()
 
 do_try_compile(bld)
 
+add_executable(source_target_test_bld source_target_test.cpp)
+target_link_libraries(source_target_test_bld bld::source_target)
+target_compile_definitions(source_target_test_bld PRIVATE USE_FROM_BUILD_DIR)
+
+add_executable(source_target_test_exp source_target_test.cpp)
+target_link_libraries(source_target_test_exp exp::source_target)
+target_compile_definitions(source_target_test_exp PRIVATE USE_FROM_INSTALL_DIR)
+
 add_executable(headeronlytest_exp headeronlytest.cpp)
 target_link_libraries(headeronlytest_exp exp::headeronly)
 

Tests/ExportImport/Import/Interface/source_target_test.cpp

@@ -0,0 +1,7 @@
+
+extern int source_symbol();
+
+int main()
+{
+  return source_symbol() - 42;
+}

Tests/RunCMake/CMakeLists.txt

@@ -192,6 +192,9 @@ add_RunCMake_test(ExternalProject)
 set(IfacePaths_INCLUDE_DIRECTORIES_ARGS -DTEST_PROP=INCLUDE_DIRECTORIES)
 add_RunCMake_test(IfacePaths_INCLUDE_DIRECTORIES TEST_DIR IfacePaths)
 
+set(IfacePaths_SOURCES_ARGS -DTEST_PROP=SOURCES)
+add_RunCMake_test(IfacePaths_SOURCES TEST_DIR IfacePaths)
+
 if(RPMBUILD)
   add_RunCMake_test(CPackRPM)
 endif()

Tests/RunCMake/IfacePaths/BinInInstallPrefix-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths_SOURCES/prefix/BinInInstallPrefix-build/empty.cpp"
+
+  which is prefixed in the build directory.

Tests/RunCMake/IfacePaths/BinaryDirectoryInInterface-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths_SOURCES/BinaryDirectoryInInterface-build/empty.cpp"
+
+  which is prefixed in the build directory.

Tests/RunCMake/IfacePaths/BinaryDirectoryInInterface.cmake

@@ -2,7 +2,11 @@
 enable_language(CXX)
 
 add_library(testTarget "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
-target_include_directories(testTarget INTERFACE "${CMAKE_CURRENT_BINARY_DIR}/foo")
+if (TEST_PROP STREQUAL INCLUDE_DIRECTORIES)
+  set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_BINARY_DIR}/foo")
+else()
+  set_property(TARGET testTarget PROPERTY INTERFACE_SOURCES "${CMAKE_CURRENT_BINARY_DIR}/empty.cpp")
+endif()
 
 install(TARGETS testTarget EXPORT testTargets
   DESTINATION lib

Tests/RunCMake/IfacePaths/DirInInstallPrefix.cmake

@@ -1,6 +1,11 @@
 enable_language(CXX)
 add_library(testTarget empty.cpp)
-target_include_directories(testTarget INTERFACE "${CMAKE_INSTALL_PREFIX}/dir")
+
+if (TEST_PROP STREQUAL INCLUDE_DIRECTORIES)
+  set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/dir")
+else()
+  set_property(TARGET testTarget PROPERTY INTERFACE_SOURCES "${CMAKE_INSTALL_PREFIX}/empty.cpp")
+endif()
 
 install(TARGETS testTarget EXPORT testTargets
   DESTINATION lib

Tests/RunCMake/IfacePaths/InstallInBinDir-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths_SOURCES/InstallInBinDir-build/empty.cpp"
+
+  which is prefixed in the build directory.

Tests/RunCMake/IfacePaths/InstallInSrcDir-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths_SOURCES/copy/empty.cpp"
+
+  which is prefixed in the source directory.

Tests/RunCMake/IfacePaths/RelativePathInGenex-stderr_SOURCES.txt

@@ -0,0 +1,4 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" contains relative path in its INTERFACE_SOURCES:
+
+    "empty.cpp"

Tests/RunCMake/IfacePaths/RelativePathInGenex.cmake

@@ -2,7 +2,12 @@
 enable_language(CXX)
 
 add_library(testTarget "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
-set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "$<1:foo>")
+
+if (TEST_PROP STREQUAL INCLUDE_DIRECTORIES)
+  set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "$<1:foo>")
+else()
+  set_property(TARGET testTarget PROPERTY INTERFACE_SOURCES "$<1:empty.cpp>")
+endif()
 
 add_library(userTarget "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
 target_link_libraries(userTarget testTarget)

Tests/RunCMake/IfacePaths/RelativePathInInterface-stderr_SOURCES.txt

@@ -0,0 +1,4 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains relative path:
+
+    "empty.cpp"

Tests/RunCMake/IfacePaths/RelativePathInInterface.cmake

@@ -2,8 +2,11 @@
 enable_language(CXX)
 
 add_library(testTarget "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
-set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "foo")
-
+if (TEST_PROP STREQUAL INCLUDE_DIRECTORIES)
+  set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "foo")
+else()
+  set_property(TARGET testTarget PROPERTY INTERFACE_SOURCES "empty.cpp")
+endif()
 install(TARGETS testTarget EXPORT testTargets
   DESTINATION lib
 )

Tests/RunCMake/IfacePaths/SourceDirectoryInInterface-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths/empty.cpp"
+
+  which is prefixed in the source directory.

Tests/RunCMake/IfacePaths/SourceDirectoryInInterface.cmake

@@ -2,7 +2,11 @@
 enable_language(CXX)
 
 add_library(testTarget "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
-target_include_directories(testTarget INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}/foo")
+if (TEST_PROP STREQUAL INCLUDE_DIRECTORIES)
+  set_property(TARGET testTarget PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_SOURCE_DIR}/foo")
+else()
+  set_property(TARGET testTarget PROPERTY INTERFACE_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp")
+endif()
 
 install(TARGETS testTarget EXPORT testTargets
   DESTINATION lib

Tests/RunCMake/IfacePaths/SrcInInstallPrefix-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/IfacePaths/SrcInInstallPrefix-stderr_SOURCES.txt

@@ -0,0 +1,6 @@
+CMake Error in CMakeLists.txt:
+  Target "testTarget" INTERFACE_SOURCES property contains path:
+
+    ".*Tests/RunCMake/IfacePaths_SOURCES/prefix/src/empty.cpp"
+
+  which is prefixed in the source directory.

Tests/RunCMake/IfacePaths/export-NOWARN.cmake

@@ -1,19 +1,34 @@
 enable_language(CXX)
 add_library(foo empty.cpp)
+
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<0:>/include/subdir)
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<INSTALL_PREFIX>/include/subdir)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<0:>/include/subdir/empty.cpp)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<INSTALL_PREFIX>/include/subdir/empty.cpp)
 
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include/subdir>)
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<INSTALL_INTERFACE:include/subdir>)
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<INSTALL_INTERFACE:include/$<0:>>)
 set_property(TARGET foo APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES $<INSTALL_INTERFACE:$<0:>/include>)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include/subdir/empty.cpp>)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<INSTALL_INTERFACE:include/subdir/empty.cpp>)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<INSTALL_INTERFACE:include/subdir/empty.cpp$<0:>>)
+set_property(TARGET foo APPEND PROPERTY INTERFACE_SOURCES $<INSTALL_INTERFACE:$<0:>/include/subdir/empty.cpp>)
 
 # target_include_directories(foo INTERFACE include/subdir) # Does and should warn. INSTALL_INTERFACE must not list src dir paths.
 target_include_directories(foo INTERFACE $<0:>/include/subdir) # Does not and should not should warn, because it starts with a genex.
 target_include_directories(foo INTERFACE $<INSTALL_PREFIX>/include/subdir)
+target_sources(foo INTERFACE $<0:>/include/subdir/empty.cpp)
+target_sources(foo INTERFACE $<INSTALL_PREFIX>/include/subdir/empty.cpp)
 
 target_include_directories(foo INTERFACE $<INSTALL_INTERFACE:include/subdir>)
 target_include_directories(foo INTERFACE $<INSTALL_INTERFACE:include/$<0:>>)
+target_sources(foo INTERFACE $<INSTALL_INTERFACE:include/subdir/empty.cpp>)
+target_sources(foo INTERFACE $<INSTALL_INTERFACE:include/subdir/empty.cpp$<0:>>)
+
+install(FILES include/subdir/empty.cpp
+  DESTINATION include/subdir
+)
 
 install(TARGETS foo EXPORT FooTargets DESTINATION lib)
 install(EXPORT FooTargets DESTINATION lib/cmake)

Tests/RunCMake/TargetSources/ExportBuild-result.txt

@@ -1 +1 @@
-1
+0

Tests/RunCMake/TargetSources/ExportBuild-stderr.txt

@@ -1 +0,0 @@
-CMake Error: Target "iface" has a populated INTERFACE_SOURCES property.  This is not currently supported.

Tests/RunCMake/TargetSources/ExportInstall-stderr.txt

@@ -1 +0,0 @@
-CMake Error: Target "iface" has a populated INTERFACE_SOURCES property.  This is not currently supported.

Tests/RunCMake/TargetSources/ExportInstall.cmake

@@ -1,6 +0,0 @@
-
-add_library(iface INTERFACE)
-target_sources(iface INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}/empty_1.cpp")
-
-install(TARGETS iface EXPORT exp)
-install(EXPORT exp DESTINATION cmake)

Tests/RunCMake/TargetSources/RunCMakeTest.cmake

@@ -10,4 +10,3 @@ endif()
 run_cmake(CMP0026-LOCATION)
 run_cmake(RelativePathInInterface)
 run_cmake(ExportBuild)
-run_cmake(ExportInstall)