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.

7 files changed, 119 insertions, 0 deletions

diff --git a/Tests/AliasTarget/CMakeLists.txt b/Tests/AliasTarget/CMakeLists.txt
new file mode 100644
index 0000000..a5eb0f6
--- /dev/null
+++ b/Tests/AliasTarget/CMakeLists.txt
@@ -0,0 +1,47 @@
+
+cmake_minimum_required(VERSION 2.8.11)
+project(AliasTarget)
+
+add_library(foo SHARED empty.cpp)
+add_library(PREFIX::Foo ALIAS foo)
+add_library(Another::Alias ALIAS foo)
+
+add_library(objects OBJECT object.cpp)
+add_library(Alias::Objects ALIAS objects)
+
+target_compile_definitions(foo PUBLIC FOO_DEFINE)
+
+add_library(bar SHARED empty.cpp)
+target_compile_definitions(bar PUBLIC BAR_DEFINE)
+
+target_link_libraries(foo LINK_PUBLIC $<$<STREQUAL:$<TARGET_PROPERTY:PREFIX::Foo,ALIASED_TARGET>,foo>:bar>)
+
+add_executable(AliasTarget commandgenerator.cpp $<TARGET_OBJECTS:Alias::Objects>)
+add_executable(PREFIX::AliasTarget ALIAS AliasTarget)
+add_executable(Generator::Command ALIAS AliasTarget)
+
+add_custom_command(OUTPUT commandoutput.h COMMAND Generator::Command)
+
+add_library(bat SHARED bat.cpp "${CMAKE_CURRENT_BINARY_DIR}/commandoutput.h")
+target_link_libraries(bat PREFIX::Foo)
+target_include_directories(bat PRIVATE "${CMAKE_CURRENT_BINARY_DIR}")
+
+add_executable(targetgenerator targetgenerator.cpp)
+add_executable(Generator::Target ALIAS targetgenerator)
+
+add_custom_target(usealias Generator::Target)
+add_dependencies(bat usealias)
+
+if (NOT TARGET Another::Alias)
+  message(SEND_ERROR "Another::Alias is not considered a target.")
+endif()
+
+get_target_property(_alt PREFIX::Foo ALIASED_TARGET)
+if (NOT ${_alt} STREQUAL foo)
+  message(SEND_ERROR "ALIASED_TARGET is not foo: ${_alt}")
+endif()
+
+get_property(_alt2 TARGET PREFIX::Foo PROPERTY ALIASED_TARGET)
+if (NOT ${_alt2} STREQUAL foo)
+  message(SEND_ERROR "ALIASED_TARGET is not foo.")
+endif()
diff --git a/Tests/AliasTarget/bat.cpp b/Tests/AliasTarget/bat.cpp
new file mode 100644
index 0000000..1063c21
--- /dev/null
+++ b/Tests/AliasTarget/bat.cpp
@@ -0,0 +1,28 @@
+
+#ifndef FOO_DEFINE
+#error Expected FOO_DEFINE
+#endif
+
+#ifndef BAR_DEFINE
+#error Expected Bar_DEFINE
+#endif
+
+#include "commandoutput.h"
+
+#ifndef COMMANDOUTPUT_DEFINE
+#error Expected COMMANDOUTPUT_DEFINE
+#endif
+
+#include "targetoutput.h"
+
+#ifndef TARGETOUTPUT_DEFINE
+#error Expected TARGETOUTPUT_DEFINE
+#endif
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int bar()
+{
+  return 0;
+}
diff --git a/Tests/AliasTarget/commandgenerator.cpp b/Tests/AliasTarget/commandgenerator.cpp
new file mode 100644
index 0000000..23560a4
--- /dev/null
+++ b/Tests/AliasTarget/commandgenerator.cpp
@@ -0,0 +1,15 @@
+
+#include <fstream>
+
+#include "object.h"
+
+int main(int argc, char **argv)
+{
+  std::fstream fout;
+  fout.open("commandoutput.h", std::ios::out);
+  if (!fout)
+    return 1;
+  fout << "#define COMMANDOUTPUT_DEFINE\n";
+  fout.close();
+  return object();
+}
diff --git a/Tests/AliasTarget/empty.cpp b/Tests/AliasTarget/empty.cpp
new file mode 100644
index 0000000..b19427a
--- /dev/null
+++ b/Tests/AliasTarget/empty.cpp
@@ -0,0 +1,7 @@
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int main(void)
+{
+  return 0;
+}
diff --git a/Tests/AliasTarget/object.cpp b/Tests/AliasTarget/object.cpp
new file mode 100644
index 0000000..df09c20
--- /dev/null
+++ b/Tests/AliasTarget/object.cpp
@@ -0,0 +1,5 @@
+
+int object(void)
+{
+  return 0;
+}
diff --git a/Tests/AliasTarget/object.h b/Tests/AliasTarget/object.h
new file mode 100644
index 0000000..e935f14
--- /dev/null
+++ b/Tests/AliasTarget/object.h
@@ -0,0 +1,4 @@
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int object(void);
diff --git a/Tests/AliasTarget/targetgenerator.cpp b/Tests/AliasTarget/targetgenerator.cpp
new file mode 100644
index 0000000..3362414
--- /dev/null
+++ b/Tests/AliasTarget/targetgenerator.cpp
@@ -0,0 +1,13 @@
+
+#include <fstream>
+
+int main(int argc, char **argv)
+{
+  std::fstream fout;
+  fout.open("targetoutput.h", std::ios::out);
+  if (!fout)
+    return 1;
+  fout << "#define TARGETOUTPUT_DEFINE\n";
+  fout.close();
+  return 0;
+}