export: Error when exporting a target without a language

First, it prevents a NULL dereference and second it reiterates that
targets without languages are not supported by CMake.

Add a RunCMake.ExportWithoutLanguage test exporting a library without a
languages.

7 files changed, 26 insertions, 0 deletions

diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 90e6d51..4de1aae 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -349,6 +349,16 @@ void getCompatibleInterfaceProperties(cmTarget *target,
 {
   cmComputeLinkInformation *info = target->GetLinkInformation(config);
 
+  if (!info)
+    {
+    cmMakefile* mf = target->GetMakefile();
+    cmOStringStream e;
+    e << "Exporting the target \"" << target->GetName() << "\" is not "
+         "allowed since its linker language cannot be determined";
+    mf->IssueMessage(cmake::FATAL_ERROR, e.str());
+    return;
+    }
+
   const cmComputeLinkInformation::ItemVector &deps = info->GetItems();
 
   for(cmComputeLinkInformation::ItemVector::const_iterator li =
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index 12f68d7..d561c34 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -115,4 +115,5 @@ if("${CMAKE_TEST_GENERATOR}" MATCHES "Visual Studio [^6]")
 endif()
 
 add_RunCMake_test(File_Generate)
+add_RunCMake_test(ExportWithoutLanguage)
 add_RunCMake_test(target_link_libraries)
diff --git a/Tests/RunCMake/ExportWithoutLanguage/CMakeLists.txt b/Tests/RunCMake/ExportWithoutLanguage/CMakeLists.txt
new file mode 100644
index 0000000..e8db6b0
--- /dev/null
+++ b/Tests/RunCMake/ExportWithoutLanguage/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 2.8)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-result.txt b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-stderr.txt b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-stderr.txt
new file mode 100644
index 0000000..67a0ae3
--- /dev/null
+++ b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage-stderr.txt
@@ -0,0 +1,6 @@
+CMake Error: CMake can not determine linker language for target: NoLanguage
+CMake Error at NoLanguage.cmake:2 \(export\):
+  Exporting the target "NoLanguage" is not allowed since its linker language
+  cannot be determined
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/ExportWithoutLanguage/NoLanguage.cmake b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage.cmake
new file mode 100644
index 0000000..2ede854
--- /dev/null
+++ b/Tests/RunCMake/ExportWithoutLanguage/NoLanguage.cmake
@@ -0,0 +1,2 @@
+add_library(NoLanguage header.h)
+export(TARGETS NoLanguage FILE "${CMAKE_CURRENT_BINARY_DIR}/export.cmake")
diff --git a/Tests/RunCMake/ExportWithoutLanguage/RunCMakeTest.cmake b/Tests/RunCMake/ExportWithoutLanguage/RunCMakeTest.cmake
new file mode 100644
index 0000000..f77f4eb
--- /dev/null
+++ b/Tests/RunCMake/ExportWithoutLanguage/RunCMakeTest.cmake
@@ -0,0 +1,3 @@
+include(RunCMake)
+
+run_cmake(NoLanguage)