[Dependency Scanning] Scan embedded header content if file doesn't exist

lib/DependencyScan/ModuleDependencyScanner.cpp

@@ -36,6 +36,7 @@
 #include "llvm/CAS/CachingOnDiskFileSystem.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/MemoryBufferRef.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/VersionTuple.h"
@@ -1063,6 +1064,42 @@ void ModuleDependencyScanner::resolveHeaderDependenciesForModule(
   if (!isTextualModuleWithABridgingHeader && !isBinaryModuleWithHeaderInput)
     return;
 
+
+  std::optional<std::string> headerPath;
+  std::unique_ptr<llvm::MemoryBuffer> sourceBuffer;
+  std::optional<llvm::MemoryBufferRef> sourceBufferRef;
+
+  auto extractHeaderContent =
+      [&](const SwiftBinaryModuleDependencyStorage &binaryMod)
+      -> std::unique_ptr<llvm::MemoryBuffer> {
+    auto header = binaryMod.headerImport;
+    // Check to see if the header input exists on disk.
+    auto FS = ScanASTContext.SourceMgr.getFileSystem();
+    if (FS->exists(header))
+      return nullptr;
+
+    auto moduleBuf = FS->getBufferForFile(binaryMod.compiledModulePath);
+    if (!moduleBuf)
+      return nullptr;
+
+    auto content = extractEmbeddedBridgingHeaderContent(std::move(*moduleBuf),
+                                                        ScanASTContext);
+    if (content.empty())
+      return nullptr;
+
+    return llvm::MemoryBuffer::getMemBufferCopy(content, header);
+  };
+
+  if (isBinaryModuleWithHeaderInput) {
+    auto &binaryMod = *moduleDependencyInfo.getAsSwiftBinaryModule();
+    if (auto embeddedHeader = extractHeaderContent(binaryMod)) {
+      sourceBuffer = std::move(embeddedHeader);
+      sourceBufferRef = sourceBuffer->getMemBufferRef();
+    } else
+      headerPath = binaryMod.headerImport;
+  } else
+    headerPath = *moduleDependencyInfo.getBridgingHeader();
+
   withDependencyScanningWorker(
       [&](ModuleDependencyScanningWorker *ScanningWorker) {
         auto clangImporter = static_cast<ClangImporter *>(
@@ -1072,12 +1109,9 @@ void ModuleDependencyScanner::resolveHeaderDependenciesForModule(
         std::optional<std::string> includeTreeID;
         std::vector<std::string> bridgingHeaderCommandLine;
         auto headerScan = clangImporter->getHeaderDependencies(
-            moduleID,
-            isTextualModuleWithABridgingHeader
-                ? *moduleDependencyInfo.getBridgingHeader()
-                : moduleDependencyInfo.getAsSwiftBinaryModule()->headerImport,
-            /*sourceBuffer=*/std::nullopt, ScanningWorker->clangScanningTool,
-            cache, headerClangModuleDependencies, headerFileInputs,
+            moduleID, headerPath, sourceBufferRef,
+            ScanningWorker->clangScanningTool, cache,
+            headerClangModuleDependencies, headerFileInputs,
             bridgingHeaderCommandLine, includeTreeID);
         if (!headerScan) {
           // Record direct header Clang dependencies

test/ScanDependencies/embedded-header.swift

@@ -0,0 +1,86 @@
+// REQUIRES: objc_interop
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -emit-module -module-name Test -module-cache-path %t/clang-module-cache -O \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
+// RUN:   %t/test.swift -o %t/Test.swiftmodule \
+// RUN:   -Xcc -fmodule-map-file=%t/a.modulemap -Xcc -fmodule-map-file=%t/b.modulemap -import-objc-header %t/Bridging.h
+
+// RUN: %target-swift-frontend -scan-dependencies -module-name User -module-cache-path %t/clang-module-cache -O \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
+// RUN:   %t/user.swift -o %t/deps.json \
+// RUN:   -Xcc -fmodule-map-file=%t/a.modulemap -Xcc -fmodule-map-file=%t/b.modulemap -I %t
+
+/// Remove bridging header from disk and rescan
+// RUN: rm -rf %t/Bridging.h %t/Foo.h %t/Foo2.h
+// RUN: %target-swift-frontend -scan-dependencies -module-name User -module-cache-path %t/clang-module-cache -O \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
+// RUN:   %t/user.swift -o %t/deps2.json \
+// RUN:   -Xcc -fmodule-map-file=%t/a.modulemap -Xcc -fmodule-map-file=%t/b.modulemap -I %t
+
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps.json swiftPrebuiltExternal:Test headerModuleDependencies | %FileCheck %s --check-prefix=MODULE
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps.json swiftPrebuiltExternal:Test headerDependenciesSourceFiles | %FileCheck %s --check-prefix=FILE
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps2.json swiftPrebuiltExternal:Test headerModuleDependencies | %FileCheck %s --check-prefix=MODULE
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps2.json swiftPrebuiltExternal:Test headerDependenciesSourceFiles | %FileCheck %s --check-prefix=FILE
+
+// MODULE: "A"
+// FILE: Bridging.h
+
+//--- test.swift
+public func test() {
+    b()
+}
+public class TestB: B {}
+
+//--- user.swift
+import Test
+
+func user() {
+  var b: TestB
+  test()
+}
+
+extension A {
+    public func testA() {}
+}
+
+//--- Bridging.h
+#include "Foo.h"
+#include "Foo2.h"
+
+//--- Foo.h
+#import "a.h"
+#ifndef IMPORT_FOO
+#define IMPORT_FOO
+int Foo = 0;
+#endif
+
+//--- Foo2.h
+#ifndef IMPORT_FOO2
+#define IMPORT_FOO2
+int Foo2 = 0;
+#endif
+
+//--- a.h
+#include "b.h"
+struct A {
+  int a;
+};
+
+//--- b.h
+void b(void);
+@interface B
+@end
+
+//--- a.modulemap
+module A {
+  header "a.h"
+  export *
+}
+
+//--- b.modulemap
+module B {
+  header "b.h"
+  export *
+}