Add the ALIAS target concept for libraries and executables.

* The ALIAS name must match a validity regex.
* Executables and libraries may be aliased.
* An ALIAS acts immutable. It can not be used as the lhs
  of target_link_libraries or other commands.
* An ALIAS can be used with add_custom_command, add_custom_target,
  and add_test in the same way regular targets can.
* The target of an ALIAS can be retrieved with the ALIASED_TARGET
  target property.
* An ALIAS does not appear in the generated buildsystem. It
  is kept separate from cmMakefile::Targets for that reason.
* A target may have multiple aliases.
* An ALIAS target may not itself have an alias.
* An IMPORTED target may not have an alias.
* An ALIAS may not be exported or imported.

1 files changed, 7 insertions, 0 deletions

diff --git a/Tests/RunCMake/alias_targets/multiple-targets.cmake b/Tests/RunCMake/alias_targets/multiple-targets.cmake
new file mode 100644
index 0000000..811eb7a
--- /dev/null
+++ b/Tests/RunCMake/alias_targets/multiple-targets.cmake
@@ -0,0 +1,7 @@
+
+enable_language(CXX)
+
+add_library(foo empty.cpp)
+add_library(bar empty.cpp)
+
+add_library(alias ALIAS foo bar)