[CMake] Check if passthrough variables are defined

Checking if they evaluate to true cases prevents passing values that evaluate to false cases. Instead we should check if the variables are defined.

llvm-svn: 282122

diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 12f79df..9b7322e 100644 (file)
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -610,7 +610,7 @@ if (CLANG_ENABLE_BOOTSTRAP)
 
   # Populate the passthrough variables
   foreach(variableName ${CLANG_BOOTSTRAP_PASSTHROUGH} ${_BOOTSTRAP_DEFAULT_PASSTHROUGH})
-    if(${variableName})
+    if(DEFINED ${variableName})
       string(REPLACE ";" "\;" value ${${variableName}})
       list(APPEND PASSTHROUGH_VARIABLES
         -D${variableName}=${value})