From 1046b122a30d5f70af379ae3c71d760f4b11b2e9 Mon Sep 17 00:00:00 2001
From: Sam Edwards <CFSworks@gmail.com>
Date: Wed, 22 Jan 2020 02:35:11 -0700
Subject: [PATCH] CMake: Fix Interrogate macro sometimes passing -D''

---
 cmake/macros/Interrogate.cmake | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cmake/macros/Interrogate.cmake b/cmake/macros/Interrogate.cmake
index 9001d05ff1..6809d8eaec 100644
--- a/cmake/macros/Interrogate.cmake
+++ b/cmake/macros/Interrogate.cmake
@@ -218,7 +218,10 @@ function(interrogate_sources target output database language_flags)
     # that's fine, it also ignores '"'
     set(_q "'")
   endif()
-  set(define_flags "$<$<BOOL:${_compile_defs}>:-D${_q}$<JOIN:${_compile_defs},${_q}\t-D${_q}>${_q}>")
+  set(_compile_defs_flags "-D${_q}$<JOIN:${_compile_defs},${_q}\t-D${_q}>${_q}")
+  # We may have just ended up with -D'' if there are no flags; filter that
+  set(define_flags
+    "$<$<NOT:$<STREQUAL:${_compile_defs_flags},-D${_q}${_q}>>:${_compile_defs_flags}>")
 
   # Some of the definitions may be specified using -D flags in the global
   # CXX_FLAGS variables; parse those out (this also picks up NDEBUG)