Deprecate Visual Studio 8 2005 generator

Update documentation to mark the generator deprecated.  Add a warning at
the end of generation plus an option to turn off the warning.

Help/generator/Visual Studio 8 2005.rst

 Visual Studio 8 2005
 --------------------
 
-Generates Visual Studio 8 2005 project files.
+Deprecated.  Generates Visual Studio 8 2005 project files.
+
+.. note::
+  This generator is deprecated and will be removed in a future version
+  of CMake.  It will still be possible to build with VS 8 2005 tools
+  using the :generator:`Visual Studio 10 2010` (or above) generator
+  with :variable:`CMAKE_GENERATOR_TOOLSET` set to ``v80``, or by
+  using the :generator:`NMake Makefiles` generator.
 
 The :variable:`CMAKE_GENERATOR_PLATFORM` variable may be set
 to specify a target platform name.

Help/release/dev/vs8-deprecate.rst

+vs8-deprecate
+-------------
+
+* The :generator:`Visual Studio 8 2005` generator is now deprecated
+  and will be removed in a future version of CMake.

Source/cmGlobalVisualStudio7Generator.cxx

@@ -293,6 +293,19 @@ void cmGlobalVisualStudio7Generator::Generate()
   if (!cmSystemTools::GetErrorOccuredFlag()) {
     this->CallVisualStudioMacro(MacroReload);
   }
+
+  if (this->Version == VS8 && !this->CMakeInstance->GetIsInTryCompile()) {
+    const char* cmakeWarnVS8 =
+      this->CMakeInstance->GetState()->GetCacheEntryValue("CMAKE_WARN_VS8");
+    if (!cmakeWarnVS8 || !cmSystemTools::IsOff(cmakeWarnVS8)) {
+      this->CMakeInstance->IssueMessage(
+        cmake::WARNING,
+        "The \"Visual Studio 8 2005\" generator is deprecated "
+        "and will be removed in a future version of CMake."
+        "\n"
+        "Add CMAKE_WARN_VS8=OFF to the cache to disable this warning.");
+    }
+  }
 }
 
 void cmGlobalVisualStudio7Generator::OutputSLNFile(

Source/cmGlobalVisualStudio8Generator.cxx

@@ -54,7 +54,7 @@ public:
   void GetDocumentation(cmDocumentationEntry& entry) const CM_OVERRIDE
   {
     entry.Name = std::string(vs8generatorName) + " [arch]";
-    entry.Brief = "Generates Visual Studio 2005 project files.  "
+    entry.Brief = "Deprecated.  Generates Visual Studio 2005 project files.  "
                   "Optional [arch] can be \"Win64\".";
   }
 

Tests/RunCMake/CommandLine/DeprecateVS8-WARN-ON-stderr.txt

+^CMake Warning:
+  The "Visual Studio 8 2005" generator is deprecated and will be removed in a
+  future version of CMake.
+
+  Add CMAKE_WARN_VS8=OFF to the cache to disable this warning.$

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -78,6 +78,13 @@ if(RunCMake_GENERATOR STREQUAL "Ninja")
   unset(RunCMake_TEST_NO_CLEAN)
 endif()
 
+if(RunCMake_GENERATOR MATCHES "^Visual Studio 8 2005")
+  set(RunCMake_WARN_VS8 1)
+  run_cmake(DeprecateVS8-WARN-ON)
+  unset(RunCMake_WARN_VS8)
+  run_cmake(DeprecateVS8-WARN-OFF)
+endif()
+
 if(UNIX)
   run_cmake_command(E_create_symlink-no-arg
     ${CMAKE_COMMAND} -E create_symlink

Tests/RunCMake/RunCMake.cmake

@@ -51,6 +51,9 @@ function(run_cmake test)
   if(APPLE)
     list(APPEND RunCMake_TEST_OPTIONS -DCMAKE_POLICY_DEFAULT_CMP0025=NEW)
   endif()
+  if(RunCMake_GENERATOR MATCHES "^Visual Studio 8 2005" AND NOT RunCMake_WARN_VS8)
+    list(APPEND RunCMake_TEST_OPTIONS -DCMAKE_WARN_VS8=OFF)
+  endif()
   if(RunCMake_MAKE_PROGRAM)
     list(APPEND RunCMake_TEST_OPTIONS "-DCMAKE_MAKE_PROGRAM=${RunCMake_MAKE_PROGRAM}")
   endif()