[ScanDependencies] Fix a bug in rewrite from swiftlang#81454

When improving the speed of dependency scanning when the new clang API
to speed up bridging, some unintended change was introduced. This
restore the scanner to the behavior before swiftlang#81454

rdar://153851818

Author: cachemeifyoucan

lib/ClangImporter/ClangModuleDependencyScanner.cpp

@@ -143,11 +143,11 @@ ModuleDependencyVector ClangImporter::bridgeClangModuleDependencies(
     if (!ctx.CASOpts.EnableCaching) {
       auto &overlayFiles = invocation.getMutHeaderSearchOpts().VFSOverlayFiles;
       for (auto overlay : overlayFiles) {
+        if (llvm::is_contained(ctx.SearchPathOpts.VFSOverlayFiles, overlay))
+          continue;
         swiftArgs.push_back("-vfsoverlay");
         swiftArgs.push_back(overlay);
       }
-      // Clear overlay files since they are forwarded from swift to clang.
-      overlayFiles.clear();
     }
 
     // Add args reported by the scanner.

test/ScanDependencies/preserve_used_vfs.swift

@@ -2,11 +2,17 @@
 // RUN: %empty-directory(%t)
 // RUN: %empty-directory(%t/module-cache)
 // RUN: %empty-directory(%t/inputs)
+// RUN: %empty-directory(%t/inputs-2)
 // RUN: split-file %s %t
 
 // RUN: sed -e "s|OUT_DIR|%t/redirects|g"  -e "s|IN_DIR|%t/inputs|g" %t/overlay_template.yaml > %t/overlay.yaml
+// RUN: sed -e "s|OUT_DIR|%t/redirects-2|g"  -e "s|IN_DIR|%t/inputs-2|g" %t/overlay_template_2.yaml > %t/overlay-2.yaml
 
-// RUN: %target-swift-frontend -scan-dependencies -module-load-mode prefer-serialized -module-cache-path %t/module-cache %t/test.swift -o %t/deps.json -I %t/inputs -I %S/Inputs/Swift -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import -Xcc -ivfsoverlay -Xcc %t/overlay.yaml
+/// Put some files in RealFileSystem that need to be over shadow by VFS.
+// RUN: touch %t/inputs/module.modulemap
+// RUN: touch %t/inputs-2/module.modulemap
+
+// RUN: %target-swift-frontend -scan-dependencies -module-load-mode prefer-serialized -module-cache-path %t/module-cache %t/test.swift -o %t/deps.json -I %t/inputs -I %t/inputs-2 -I %S/Inputs/Swift -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import -Xcc -ivfsoverlay -Xcc %t/overlay.yaml -Xcc -ivfsoverlay -Xcc %t/overlay-2.yaml
 // RUN: %validate-json %t/deps.json | %FileCheck %s
 
 // RUN: %{python} %S/../CAS/Inputs/BuildCommandExtractor.py %t/deps.json clang:SwiftShims > %t/shim.cmd
@@ -15,6 +21,8 @@
 // RUN: %swift_frontend_plain @%t/swift.cmd
 // RUN: %{python} %S/../CAS/Inputs/BuildCommandExtractor.py %t/deps.json SwiftOnoneSupport > %t/onone.cmd
 // RUN: %swift_frontend_plain @%t/onone.cmd
+// RUN: %{python} %S/../CAS/Inputs/BuildCommandExtractor.py %t/deps.json clang:Indirect > %t/Indirect.cmd
+// RUN: %swift_frontend_plain @%t/Indirect.cmd
 // RUN: %{python} %S/../CAS/Inputs/BuildCommandExtractor.py %t/deps.json clang:F > %t/F.cmd
 // RUN: %swift_frontend_plain @%t/F.cmd
 // RUN: %{python} %S/../CAS/Inputs/BuildCommandExtractor.py %t/deps.json F > %t/SwiftF.cmd
@@ -28,10 +36,11 @@
 // RUN: echo "\"-explicit-swift-module-map-file\"" >> %t/MyApp.cmd
 // RUN: echo "\"%t/map.json\"" >> %t/MyApp.cmd
 
-// RUN: %target-swift-frontend @%t/MyApp.cmd %t/test.swift -Xcc -ivfsoverlay -Xcc %t/overlay.yaml \
+// RUN: %target-swift-frontend @%t/MyApp.cmd %t/test.swift -Xcc -ivfsoverlay -Xcc %t/overlay.yaml -Xcc -ivfsoverlay -Xcc %t/overlay-2.yaml \
 // RUN:   -emit-module -o %t/Test.swiftmodule
 
 //--- redirects/RedirectedF.h
+#include "Indirect_2.h"
 void funcRedirectedF(void);
 
 //--- redirects/modulemap
@@ -40,6 +49,15 @@ module F {
   export *
 }
 
+//--- redirects-2/RedirectedIndirect.h
+void funcRedirectedIndirect(void);
+
+//--- redirects-2/modulemap
+module Indirect {
+  header "Indirect_2.h"
+  export *
+}
+
 //--- overlay_template.yaml
 {
   'version': 0,
@@ -59,10 +77,30 @@ module F {
   ]
 }
 
+//--- overlay_template_2.yaml
+{
+  'version': 0,
+  'use-external-names': false,
+  'roots': [
+    {
+      'name': 'IN_DIR', 'type': 'directory',
+      'contents': [
+        { 'name': 'Indirect_2.h', 'type': 'file',
+          'external-contents': 'OUT_DIR/RedirectedIndirect.h'
+        },
+        { 'name': 'module.modulemap', 'type': 'file',
+          'external-contents': 'OUT_DIR/modulemap'
+        }
+      ]
+    },
+  ]
+}
+
 //--- test.swift
 import F
 
 func testF() { funcRedirectedF() }
+func testIndirect() { funcRedirectedIndirect() }
 
 // CHECK: "mainModuleName": "deps"
 /// --------Main module
@@ -94,11 +132,33 @@ func testF() { funcRedirectedF() }
 // CHECK: "-ivfsoverlay",
 // CHECK-NEXT: "-Xcc",
 // CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay.yaml",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "-ivfsoverlay",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay-2.yaml",
 // CHECK: ],
 
 /// --------Clang module F
 // CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}F-{{.*}}.pcm",
 // CHECK: "commandLine": [
 // CHECK: "-vfsoverlay",
 // CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay.yaml",
-// CHECK: ],
+// CHECK-NEXT: "-vfsoverlay",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay-2.yaml",
+// CHECK: "-ivfsoverlay",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay.yaml",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "-ivfsoverlay",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay-2.yaml",
+// CHECK: ]
+
+/// --------Clang module Indirect
+// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}Indirect-{{.*}}.pcm",
+// CHECK-NOT: overlay.yaml
+// CHECK: "-vfsoverlay",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay-2.yaml",
+// CHECK: "-ivfsoverlay",
+// CHECK-NEXT: "-Xcc",
+// CHECK-NEXT: "{{.*}}{{/|\\}}preserve_used_vfs.swift.tmp{{/|\\}}overlay-2.yaml",