Update root CMake to define LLVM_ENABLE_DIA_SDK when appropriate.

[zturner]

Summary

This allows all CMake projects, as well as C++ code, to detect if and when DIA SDK is available for use.

This is independent of actually having any DIA-based code in the codebase, so in theory can go in now, even though the DIA stuff isn't in yet.

I'm not sure if I did this correctly. LMK if I overlooked something or if I'm going about this wrong.

[zturner]

friendly ping to bring this to the top of your inbox

[chandlerc]

include/llvm/Config/config.h.in

540–542

Need to update the config.h.cmake as well.

include/llvm/Config/llvm-config.h.cmake

83–85 ↗

(On Diff #19456)

We shouldn't expose this to our headers, or our installed headers.

[zturner]

Fix up suggestions from chandlerc. Moved the detection logic into cmake-ix as well, and renamed the variable HAVE_DIA_SDK instead of LLVM_ENABLE_DIA_SDK.

[chandlerc]

LGTM, thanks.

cmake/config-ix.cmake

   set(SHLIBEXT ".lib")
   set(stricmp "_stricmp")
   set(strdup "_strdup")
+
+  # See if the DIA SDK is available and usable.
+  set(MSVC_DIA_SDK_DIR "$ENV{VSINSTALLDIR}DIA SDK")
+
+  # Due to a bug in MSVC 2013's installation software, it is possible
+  # for MSVC 2013 to write the DIA SDK into the Visual Studio 2012
+  # install directory.  If this happens, the installation is corrupt
+  # and there's nothing we can do.  It happens with enough frequency
+  # though that we should handle it.  We do so by simply checking that
+  # the DIA SDK folder exists.  Should this happen you will need to
+  # uninstall VS 2012 and then re-install VS 2013.
+  if (IS_DIRECTORY ${MSVC_DIA_SDK_DIR})
+    set(HAVE_DIA_SDK 1)
+  else()
+    set(HAVE_DIA_SDK 0)
+  endif()
 endif( MSVC )
 
 if( PURE_WINDOWS )

include/llvm/Config/config.h.cmake

    don't. */
 #cmakedefine01 HAVE_DECL_STRERROR_S
 
+/* Define to 1 if you have the DIA SDK installed, and to 0 if you don't. */
+#cmakedefine HAVE_DIA_SDK ${HAVE_DIA_SDK}
+
 /* Define to 1 if you have the <dirent.h> header file, and it defines `DIR'.
    */
 #cmakedefine HAVE_DIRENT_H ${HAVE_DIRENT_H}

include/llvm/Config/config.h.in

    don't. */
 #undef HAVE_DECL_STRERROR_S
 
+/* Define to 1 if you have the DIA SDK installed, and to 0 if you don't. */
+#undef HAVE_DIA_SDK
+
 /* Define to 1 if you have the <dirent.h> header file, and it defines `DIR'.
    */
 #undef HAVE_DIRENT_H