GenEx: Add expressions to specify build- or install-only values

This is for specifying INCLUDE_DIRECTORIES relevant to the build-location
or the install location for example:

 set_property(TARGET foo PROPERTY
   INTERFACE_INCLUDE_DIRECTORIES
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR};${CMAKE_CURRENT_SOURCE_DIR}>"
   "$<INSTALL_INTERFACE:${CMAKE_INSTALL_PREFIX}/include>"
 )

A 'bar' target can then use:

 set_property(TARGET bar PROPERTY
   INCLUDE_DIRECTORIES
   "$<TARGET_PROPERTY:foo,INTERFACE_INCLUDE_DIRECTORIES>"
 )

and it will work whether foo is in the same project, or an imported target
from an installation location, or an imported target from a build location
generated by the export() command.

Because the generator expressions are only evaluated at build-time, these
new expressions are equivalent to the ZeroNode and OneNode.

The GeneratorExpression test is split into parts. Some shells can't run
the custom command as it is getting too long.

1 files changed, 10 insertions, 0 deletions

diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index 3b7cfc0..e20e203 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -96,6 +96,12 @@ static const struct OneNode : public cmGeneratorExpressionNode
 } oneNode;
 
 //----------------------------------------------------------------------------
+static const struct OneNode buildInterfaceNode;
+
+//----------------------------------------------------------------------------
+static const struct ZeroNode installInterfaceNode;
+
+//----------------------------------------------------------------------------
 #define BOOLEAN_OP_NODE(OPNAME, OP, SUCCESS_VALUE, FAILURE_VALUE) \
 static const struct OP ## Node : public cmGeneratorExpressionNode \
 { \
@@ -593,6 +599,10 @@ cmGeneratorExpressionNode* GetNode(const std::string &identifier)
     return &commaNode;
   else if (identifier == "TARGET_PROPERTY")
     return &targetPropertyNode;
+  else if (identifier == "BUILD_INTERFACE")
+    return &buildInterfaceNode;
+  else if (identifier == "INSTALL_INTERFACE")
+    return &installInterfaceNode;
   return 0;
 
 }