Add C API

Author: Bigcheese

clang/include/clang-c/Dependencies.h

@@ -161,6 +161,17 @@ CINDEX_DEPRECATED CINDEX_LINKAGE void
 clang_experimental_DependencyScannerServiceOptions_setActionCache(
     CXDependencyScannerServiceOptions Opts, CXCASActionCache Cache);
 
+/**
+ * Set if negative stat caching is enabled or disabled. If this is not called
+ * the default value is used.
+ *
+ * The default is false unless the environment variable
+ * `CLANG_SCAN_CACHE_NEGATIVE_STATS` is set to empty or "1".
+ */
+CINDEX_LINKAGE void
+clang_experimental_DependencyScannerServiceOptions_setCacheNegativeStats(
+    CXDependencyScannerServiceOptions Opts, bool CacheNegativeStats);
+
 /**
  * Create a \c CXDependencyScannerService object.
  * Must be disposed with \c

clang/tools/libclang/CDependencies.cpp

@@ -38,6 +38,7 @@ struct DependencyScannerServiceOptions {
   ScanningOptimizations OptimizeArgs = ScanningOptimizations::Default;
   std::shared_ptr<cas::ObjectStore> CAS;
   std::shared_ptr<cas::ActionCache> Cache;
+  std::optional<bool> CacheNegativeStats;
 
   ScanningOutputFormat getFormat() const;
 };
@@ -161,6 +162,11 @@ void clang_experimental_DependencyScannerServiceOptions_setActionCache(
   unwrap(Opts)->CASOpts.CASPath = cas::unwrap(Cache)->CachePath;
 }
 
+void clang_experimental_DependencyScannerServiceOptions_setCacheNegativeStats(
+    CXDependencyScannerServiceOptions Opts, bool CacheNegativeStats) {
+  unwrap(Opts)->CacheNegativeStats = CacheNegativeStats;
+}
+
 CXDependencyScannerService
 clang_experimental_DependencyScannerService_create_v0(CXDependencyMode Format) {
   // FIXME: Pass default CASOpts and nullptr as CachingOnDiskFileSystem now.
@@ -207,7 +213,10 @@ clang_experimental_DependencyScannerService_create_v1(
   return wrap(new DependencyScanningService(
       ScanningMode::DependencyDirectivesScan, Format, unwrap(Opts)->CASOpts,
       std::move(CAS), std::move(Cache), std::move(FS),
-      unwrap(Opts)->OptimizeArgs));
+      unwrap(Opts)->OptimizeArgs, /*EagerLoadModules=*/false,
+      /*TraceVFS=*/false, llvm::sys::toTimeT(std::chrono::system_clock::now()),
+      unwrap(Opts)->CacheNegativeStats ? *unwrap(Opts)->CacheNegativeStats
+                                       : shouldNegativeStatCacheDefault()));
 }
 
 void clang_experimental_DependencyScannerService_dispose_v0(

clang/tools/libclang/libclang.map

@@ -609,6 +609,11 @@ LLVM_21 {
     clang_experimental_DepGraphModuleLinkLibrary_isFramework;
 };
 
+LLVM_22 {
+  global:
+    clang_experimental_DependencyScannerServiceOptions_setCacheNegativeStats;
+};
+
 # Example of how to add a new symbol version entry.  If you do add a new symbol
 # version, please update the example to depend on the version you added.
 # LLVM_X {

clang/unittests/libclang/DependencyScanningCAPITests.cpp

@@ -22,6 +22,8 @@ TEST(DependencyScanningCAPITests, DependencyScanningFSCacheOutOfDate) {
 
   CXDependencyScannerServiceOptions ServiceOptions =
       clang_experimental_DependencyScannerServiceOptions_create();
+  clang_experimental_DependencyScannerServiceOptions_setCacheNegativeStats(
+      ServiceOptions, true);
   CXDependencyScannerService Service =
       clang_experimental_DependencyScannerService_create_v1(ServiceOptions);
   CXDependencyScannerWorker Worker =