From b1c19ce3837036bde3b639f8285fa228b8e6f278 Mon Sep 17 00:00:00 2001
From: Stephen Kelly <steveire@gmail.com>
Date: Fri, 14 Jun 2013 15:59:23 +0200
Subject: Genex: Make LINK_LANGUAGE report an error when evaluating link
 libraries.

---
 Source/cmGeneratorExpressionEvaluator.cxx               | 9 ++++++++-
 Tests/RunCMake/Languages/LINK_LANGUAGE-genex-result.txt | 1 +
 Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt | 6 ++++++
 Tests/RunCMake/Languages/LINK_LANGUAGE-genex.cmake      | 4 ++++
 Tests/RunCMake/Languages/RunCMakeTest.cmake             | 1 +
 Tests/RunCMake/Languages/empty.cpp                      | 7 +++++++
 6 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 Tests/RunCMake/Languages/LINK_LANGUAGE-genex-result.txt
 create mode 100644 Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt
 create mode 100644 Tests/RunCMake/Languages/LINK_LANGUAGE-genex.cmake
 create mode 100644 Tests/RunCMake/Languages/empty.cpp

diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index 3e18bba..cd0d26b 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -415,8 +415,15 @@ static const struct LinkLanguageNode : public cmGeneratorExpressionNode
   std::string Evaluate(const std::vector<std::string> &parameters,
                        cmGeneratorExpressionContext *context,
                        const GeneratorExpressionContent *content,
-                       cmGeneratorExpressionDAGChecker *) const
+                       cmGeneratorExpressionDAGChecker *dagChecker) const
   {
+    if (dagChecker && dagChecker->EvaluatingLinkLibraries())
+      {
+      reportError(context, content->GetOriginalExpression(),
+          "$<LINK_LANGUAGE> expression can not be used while evaluating "
+          "link libraries");
+      return std::string();
+      }
     if (parameters.size() != 0 && parameters.size() != 1)
       {
       reportError(context, content->GetOriginalExpression(),
diff --git a/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-result.txt b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt
new file mode 100644
index 0000000..8e0591d
--- /dev/null
+++ b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex-stderr.txt
@@ -0,0 +1,6 @@
+CMake Error:
+  Error evaluating generator expression:
+
+    \$<LINK_LANGUAGE>
+
+  \$<LINK_LANGUAGE> expression can not be used while evaluating link libraries
diff --git a/Tests/RunCMake/Languages/LINK_LANGUAGE-genex.cmake b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex.cmake
new file mode 100644
index 0000000..e0f8c57
--- /dev/null
+++ b/Tests/RunCMake/Languages/LINK_LANGUAGE-genex.cmake
@@ -0,0 +1,4 @@
+
+add_library(foo SHARED empty.cpp)
+add_library(bar SHARED empty.cpp)
+target_link_libraries(foo $<$<STREQUAL:$<LINK_LANGUAGE>,anything>:bar>)
diff --git a/Tests/RunCMake/Languages/RunCMakeTest.cmake b/Tests/RunCMake/Languages/RunCMakeTest.cmake
index a99548f..59ef5dc 100644
--- a/Tests/RunCMake/Languages/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Languages/RunCMakeTest.cmake
@@ -1,3 +1,4 @@
 include(RunCMake)
 
 run_cmake(NoLangSHARED)
+run_cmake(LINK_LANGUAGE-genex)
diff --git a/Tests/RunCMake/Languages/empty.cpp b/Tests/RunCMake/Languages/empty.cpp
new file mode 100644
index 0000000..7279c5e
--- /dev/null
+++ b/Tests/RunCMake/Languages/empty.cpp
@@ -0,0 +1,7 @@
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int empty(void)
+{
+  return 0;
+}
-- 
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