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.

4 files changed, 45 insertions, 29 deletions

diff --git a/Tests/GeneratorExpression/CMakeLists.txt b/Tests/GeneratorExpression/CMakeLists.txt
index 3a92d81..db6fb74 100644
--- a/Tests/GeneratorExpression/CMakeLists.txt
+++ b/Tests/GeneratorExpression/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required (VERSION 2.8.8)
 project(GeneratorExpression NONE)
 
-add_custom_target(check ALL
+add_custom_target(check-part1 ALL
   COMMAND ${CMAKE_COMMAND}
     -Dtest_0=$<0:nothing>
     -Dtest_0_with_comma=$<0:-Wl,--no-undefined>
@@ -57,6 +57,13 @@ add_custom_target(check ALL
     -Dtest_colons_3=$<1:Qt5::Core>
     -Dtest_colons_4=$<1:C:\\CMake>
     -Dtest_colons_5=$<1:C:/CMake>
+    -P ${CMAKE_CURRENT_SOURCE_DIR}/check-part1.cmake
+  COMMAND ${CMAKE_COMMAND} -E echo "check done (part 1 of 2)"
+  VERBATIM
+  )
+
+add_custom_target(check-part2 ALL
+  COMMAND ${CMAKE_COMMAND}
     -Dtest_incomplete_1=$<
     -Dtest_incomplete_2=$<something
     -Dtest_incomplete_3=$<something:
@@ -78,7 +85,9 @@ add_custom_target(check ALL
     -Dtest_incomplete_19=$<1:some,thing$<ANGLE-R>
     -Dtest_incomplete_20=$<CONFIGURATION$<ANGLE-R>
     -Dtest_incomplete_21=$<BOOL:something$<ANGLE-R>
-    -P ${CMAKE_CURRENT_SOURCE_DIR}/check.cmake
-  COMMAND ${CMAKE_COMMAND} -E echo "check done"
+    -Dtest_build_interface=$<BUILD_INTERFACE:build>
+    -Dtest_install_interface=$<INSTALL_INTERFACE:install>
+    -P ${CMAKE_CURRENT_SOURCE_DIR}/check-part2.cmake
+  COMMAND ${CMAKE_COMMAND} -E echo "check done (part 2 of 2)"
   VERBATIM
   )
diff --git a/Tests/GeneratorExpression/check-common.cmake b/Tests/GeneratorExpression/check-common.cmake
new file mode 100644
index 0000000..8ffebd7
--- /dev/null
+++ b/Tests/GeneratorExpression/check-common.cmake
@@ -0,0 +1,5 @@
+macro(check var val)
+  if(NOT "${${var}}" STREQUAL "${val}")
+    message(SEND_ERROR "${var} is \"${${var}}\", not \"${val}\"")
+  endif()
+endmacro()
diff --git a/Tests/GeneratorExpression/check.cmake b/Tests/GeneratorExpression/check-part1.cmake
index af436de..7abfa82 100644
--- a/Tests/GeneratorExpression/check.cmake
+++ b/Tests/GeneratorExpression/check-part1.cmake
@@ -1,8 +1,5 @@
-macro(check var val)
-  if(NOT "${${var}}" STREQUAL "${val}")
-    message(SEND_ERROR "${var} is \"${${var}}\", not \"${val}\"")
-  endif()
-endmacro()
+
+include(${CMAKE_CURRENT_LIST_DIR}/check-common.cmake)
 
 message(STATUS "config=[${config}]")
 check(test_0 "")
@@ -57,24 +54,3 @@ check(test_colons_2 "::")
 check(test_colons_3 "Qt5::Core")
 check(test_colons_4 "C:\\\\CMake")
 check(test_colons_5 "C:/CMake")
-check(test_incomplete_1 "$<")
-check(test_incomplete_2 "$<something")
-check(test_incomplete_3 "$<something:")
-check(test_incomplete_4 "$<something:,")
-check(test_incomplete_5 "$something:,>")
-check(test_incomplete_6 "<something:,>")
-check(test_incomplete_7 "$<something::")
-check(test_incomplete_8 "$<something:,")
-check(test_incomplete_9 "$<something:,,")
-check(test_incomplete_10 "$<something:,:")
-check(test_incomplete_11 "$<something,,")
-check(test_incomplete_12 "$<,,")
-check(test_incomplete_13 "$<somespecialthing")
-check(test_incomplete_14 "$<>")
-check(test_incomplete_15 "$<some$<thing")
-check(test_incomplete_16 "$<BOOL:something")
-check(test_incomplete_17 "some$thing")
-check(test_incomplete_18 "$<1:some,thing")
-check(test_incomplete_19 "$<1:some,thing>")
-check(test_incomplete_20 "$<CONFIGURATION>")
-check(test_incomplete_21 "$<BOOL:something>")
diff --git a/Tests/GeneratorExpression/check-part2.cmake b/Tests/GeneratorExpression/check-part2.cmake
new file mode 100644
index 0000000..149a658
--- /dev/null
+++ b/Tests/GeneratorExpression/check-part2.cmake
@@ -0,0 +1,26 @@
+
+include(${CMAKE_CURRENT_LIST_DIR}/check-common.cmake)
+
+check(test_incomplete_1 "$<")
+check(test_incomplete_2 "$<something")
+check(test_incomplete_3 "$<something:")
+check(test_incomplete_4 "$<something:,")
+check(test_incomplete_5 "$something:,>")
+check(test_incomplete_6 "<something:,>")
+check(test_incomplete_7 "$<something::")
+check(test_incomplete_8 "$<something:,")
+check(test_incomplete_9 "$<something:,,")
+check(test_incomplete_10 "$<something:,:")
+check(test_incomplete_11 "$<something,,")
+check(test_incomplete_12 "$<,,")
+check(test_incomplete_13 "$<somespecialthing")
+check(test_incomplete_14 "$<>")
+check(test_incomplete_15 "$<some$<thing")
+check(test_incomplete_16 "$<BOOL:something")
+check(test_incomplete_17 "some$thing")
+check(test_incomplete_18 "$<1:some,thing")
+check(test_incomplete_19 "$<1:some,thing>")
+check(test_incomplete_20 "$<CONFIGURATION>")
+check(test_incomplete_21 "$<BOOL:something>")
+check(test_build_interface "build")
+check(test_install_interface "")