1 files changed, 20 insertions, 2 deletions
diff --git a/Source/cmNinjaTargetGenerator.cxx b/Source/cmNinjaTargetGenerator.cxx
index be8bb08..7cc1581 100644
--- a/Source/cmNinjaTargetGenerator.cxx
+++ b/Source/cmNinjaTargetGenerator.cxx
@@ -877,8 +877,26 @@ void cmNinjaTargetGenerator::WriteCompileRule(const std::string& lang,
         compilerLauncher.clear();
       }
       if (cmNonempty(iwyu)) {
-        run_iwyu += cmStrCat(" --iwyu=",
-                             this->GetLocalGenerator()->EscapeForShell(*iwyu));
+        run_iwyu += " --iwyu=";
+
+        // Only add --driver-mode if it is not already specified, as adding
+        // it unconditionally might override a user-specified driver-mode
+        if (iwyu.Get()->find("--driver-mode=") == std::string::npos) {
+          cmProp p = this->Makefile->GetDefinition(
+            cmStrCat("CMAKE_", lang, "_INCLUDE_WHAT_YOU_USE_DRIVER_MODE"));
+          std::string driverMode;
+
+          if (cmNonempty(p)) {
+            driverMode = *p;
+          } else {
+            driverMode = lang == "C" ? "gcc" : "g++";
+          }
+
+          run_iwyu += this->LocalGenerator->EscapeForShell(
+            cmStrCat(*iwyu, ";--driver-mode=", driverMode));
+        } else {
+          run_iwyu += this->LocalGenerator->EscapeForShell(*iwyu);
+        }
       }
       if (cmNonempty(tidy)) {
         run_iwyu += " --tidy=";