Increase cancellation robustness
Calling `cancel()` on already cancelled builds should be a nop. Also
guard against the underlying `system` being deallocated.
diff --git a/lib/BuildSystem/BuildSystemFrontend.cpp b/lib/BuildSystem/BuildSystemFrontend.cpp
index 41ebf1c..fa2afb8 100644
--- a/lib/BuildSystem/BuildSystemFrontend.cpp
+++ b/lib/BuildSystem/BuildSystemFrontend.cpp
@@ -340,10 +340,16 @@
void BuildSystemFrontendDelegate::cancel() {
// FIXME: We should audit that a build is happening.
+ if (isCancelled_) {
+ return;
+ }
isCancelled_ = true;
auto delegateImpl = static_cast<BuildSystemFrontendDelegateImpl*>(impl);
- delegateImpl->system->cancel();
+ auto system = delegateImpl->system;
+ if (system) {
+ system->cancel();
+ }
}
void BuildSystemFrontendDelegate::resetForBuild() {
