Add generator expressions for version comparision.

Source/cmDocumentGeneratorExpressions.h

@@ -48,6 +48,12 @@
   "used.\n"                                                             \
   "  $<CXX_COMPILER_ID:comp>     = '1' if the CMake-id of the CXX "     \
   "compiler matches comp, otherwise '0'.\n"                             \
+  "  $<VERSION_GREATER:v1,v2>  = '1' if v1 is a version greater than "  \
+  "v2, else '0'.\n"                                                     \
+  "  $<VERSION_LESS:v1,v2>     = '1' if v1 is a version less than v2, " \
+  "else '0'.\n"                                                         \
+  "  $<VERSION_EQUAL:v1,v2>    = '1' if v1 is the same version as v2, " \
+  "else '0'.\n"                                                         \
   "  $<TARGET_FILE:tgt>        = main file (.exe, .so.1.2, .a)\n"       \
   "  $<TARGET_LINKER_FILE:tgt> = file used to link (.a, .lib, .so)\n"   \
   "  $<TARGET_SONAME_FILE:tgt> = file with soname (.so.3)\n"            \

Source/cmGeneratorExpressionEvaluator.cxx

@@ -344,6 +344,60 @@ static const struct CXXCompilerIdNode : public CompilerIdNode
   }
 } cxxCompilerIdNode;
 
+//----------------------------------------------------------------------------
+static const struct VersionGreaterNode : public cmGeneratorExpressionNode
+{
+  VersionGreaterNode() {}
+
+  virtual int NumExpectedParameters() const { return 2; }
+
+  std::string Evaluate(const std::vector<std::string> &parameters,
+                       cmGeneratorExpressionContext *,
+                       const GeneratorExpressionContent *,
+                       cmGeneratorExpressionDAGChecker *) const
+  {
+    return cmSystemTools::VersionCompare(cmSystemTools::OP_GREATER,
+                                         parameters.front().c_str(),
+                                         parameters[1].c_str()) ? "1" : "0";
+  }
+} versionGreaterNode;
+
+//----------------------------------------------------------------------------
+static const struct VersionLessNode : public cmGeneratorExpressionNode
+{
+  VersionLessNode() {}
+
+  virtual int NumExpectedParameters() const { return 2; }
+
+  std::string Evaluate(const std::vector<std::string> &parameters,
+                       cmGeneratorExpressionContext *,
+                       const GeneratorExpressionContent *,
+                       cmGeneratorExpressionDAGChecker *) const
+  {
+    return cmSystemTools::VersionCompare(cmSystemTools::OP_LESS,
+                                         parameters.front().c_str(),
+                                         parameters[1].c_str()) ? "1" : "0";
+  }
+} versionLessNode;
+
+//----------------------------------------------------------------------------
+static const struct VersionEqualNode : public cmGeneratorExpressionNode
+{
+  VersionEqualNode() {}
+
+  virtual int NumExpectedParameters() const { return 2; }
+
+  std::string Evaluate(const std::vector<std::string> &parameters,
+                       cmGeneratorExpressionContext *,
+                       const GeneratorExpressionContent *,
+                       cmGeneratorExpressionDAGChecker *) const
+  {
+    return cmSystemTools::VersionCompare(cmSystemTools::OP_EQUAL,
+                                         parameters.front().c_str(),
+                                         parameters[1].c_str()) ? "1" : "0";
+  }
+} versionEqualNode;
+
 //----------------------------------------------------------------------------
 static const struct ConfigurationNode : public cmGeneratorExpressionNode
 {
@@ -1169,6 +1223,12 @@ cmGeneratorExpressionNode* GetNode(const std::string &identifier)
     return &cCompilerIdNode;
   else if (identifier == "CXX_COMPILER_ID")
     return &cxxCompilerIdNode;
+  else if (identifier == "VERSION_GREATER")
+    return &versionGreaterNode;
+  else if (identifier == "VERSION_LESS")
+    return &versionLessNode;
+  else if (identifier == "VERSION_EQUAL")
+    return &versionEqualNode;
   else if (identifier == "CONFIGURATION")
     return &configurationNode;
   else if (identifier == "CONFIG")

Tests/GeneratorExpression/CMakeLists.txt

@@ -130,6 +130,12 @@ add_custom_target(check-part2 ALL
     -Dtest_arbitrary_content_comma_8=$<1:a,,b>
     -Dtest_arbitrary_content_comma_9=$<1:a,,b,,>
     -Dtest_arbitrary_content_comma_10=$<1:,,a,,b,,>
+    -Dtest_version_greater_1=$<VERSION_GREATER:1.0,1.1.1>
+    -Dtest_version_greater_2=$<VERSION_GREATER:1.1.1,1.0>
+    -Dtest_version_less_1=$<VERSION_LESS:1.1.1,1.0>
+    -Dtest_version_less_2=$<VERSION_LESS:1.0,1.1.1>
+    -Dtest_version_equal_1=$<VERSION_EQUAL:1.0.1,1.1>
+    -Dtest_version_equal_2=$<VERSION_EQUAL:1.1,1.1>
     -P ${CMAKE_CURRENT_SOURCE_DIR}/check-part2.cmake
   COMMAND ${CMAKE_COMMAND} -E echo "check done (part 2 of 2)"
   VERBATIM

Tests/GeneratorExpression/check-part2.cmake

@@ -44,3 +44,9 @@ check(test_arbitrary_content_comma_7 ",,a")
 check(test_arbitrary_content_comma_8 "a,,b")
 check(test_arbitrary_content_comma_9 "a,,b,,")
 check(test_arbitrary_content_comma_10 ",,a,,b,,")
+check(test_version_greater_1 "0")
+check(test_version_greater_2 "1")
+check(test_version_less_1 "0")
+check(test_version_less_2 "1")
+check(test_version_equal_1 "0")
+check(test_version_equal_2 "1")