[clang][depscan] Support prefix mappings when deciding modules that come from "stable" directories

clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp

@@ -586,6 +586,11 @@ class DependencyScanningAction : public tooling::ToolAction {
     auto *FileMgr = ScanInstance.createFileManager(FS);
     ScanInstance.createSourceManager(*FileMgr);
 
+    // Initialize PrefixMapper incase mappings exist.
+    DepscanPrefixMapping::configurePrefixMapper(
+        ScanInstance.getFrontendOpts().PathPrefixMappings,
+        ScanInstance.getPrefixMapper());
+
     // Create a collection of stable directories derived from the ScanInstance
     // for determining whether module dependencies would fully resolve from
     // those directories.
@@ -595,6 +600,20 @@ class DependencyScanningAction : public tooling::ToolAction {
         (llvm::sys::path::root_directory(Sysroot) != Sysroot))
       StableDirs = {Sysroot, ScanInstance.getHeaderSearchOpts().ResourceDir};
 
+    // When remapping is disabled, the stable directory paths are references to
+    // strings tied to the CompilerInstance. Otherwise, these potentially mapped
+    // strings need to be allocated. To reduce the number of downstream changes
+    // required to this support allocation, tie the lifetime of these strings to
+    // visiting all dependencies of a prebuilt module.
+    llvm::PrefixMapper &Mapper = ScanInstance.getPrefixMapper();
+    llvm::BumpPtrAllocator Allocator;
+    llvm::StringSaver StableDirStorage(Allocator);
+    if (!StableDirs.empty() && !Mapper.empty()) {
+      StableDirs.push_back(StableDirStorage.save(Mapper.mapToString(Sysroot)));
+      StableDirs.push_back(StableDirStorage.save(
+          Mapper.mapToString(ScanInstance.getHeaderSearchOpts().ResourceDir)));
+    }
+
     // Store a mapping of prebuilt module files and their properties like header
     // search options. This will prevent the implicit build to create duplicate
     // modules and will force reuse of the existing prebuilt module files

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -255,12 +255,11 @@ bool dependencies::isPathInStableDir(const ArrayRef<StringRef> Directories,
 
 bool dependencies::areOptionsInStableDir(const ArrayRef<StringRef> Directories,
                                          const HeaderSearchOptions &HSOpts) {
-  // FIXME: This breaks CAS prefix mapping tests.
-  // assert(isPathInStableDir(Directories, HSOpts.Sysroot) &&
-  //       "Sysroots differ between module dependencies and current TU");
+  assert(isPathInStableDir(Directories, HSOpts.Sysroot) &&
+         "Sysroots differ between module dependencies and current TU");
 
-  // assert(isPathInStableDir(Directories, HSOpts.ResourceDir) &&
-  //        "ResourceDirs differ between module dependencies and current TU");
+  assert(isPathInStableDir(Directories, HSOpts.ResourceDir) &&
+         "ResourceDirs differ between module dependencies and current TU");
 
   for (const auto &Entry : HSOpts.UserEntries) {
     if (!Entry.IgnoreSysRoot)

clang/test/ClangScanDeps/include-tree-with-pch.c

@@ -3,7 +3,7 @@
 // RUN: split-file %s %t
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
 
-// RUN: %clang -x c-header %t/prefix.h -target x86_64-apple-macos12 -o %t/prefix.pch -fdepscan=inline -fdepscan-include-tree -Xclang -fcas-path -Xclang %t/cas
+// RUN: %clang -x c-header %t/prefix.h -target x86_64-apple-macos12 -isysroot %t -o %t/prefix.pch -fdepscan=inline -fdepscan-include-tree -Xclang -fcas-path -Xclang %t/cas
 // RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-include-tree -cas-path %t/cas > %t/result.txt
 // RUN: FileCheck %s -input-file %t/result.txt -DPREFIX=%/t
 

clang/test/ClangScanDeps/modules-cas-trees-input-files.c

@@ -37,7 +37,7 @@
 [
   {
     "directory" : "DIR",
-    "command" : "clang_tool -I DIR -x c-header DIR/prefix.h -o DIR/prefix.h.pch -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
+    "command" : "clang -I DIR -x c-header DIR/prefix.h -o DIR/prefix.h.pch -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
     "file" : "DIR/prefix.h"
   },
 ]
@@ -46,7 +46,7 @@
 [
   {
     "directory" : "DIR",
-    "command" : "clang_tool -I DIR -fsyntax-only DIR/tu.c -include DIR/prefix.h -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
+    "command" : "clang -I DIR -fsyntax-only DIR/tu.c -include DIR/prefix.h -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
     "file" : "DIR/tu.c"
   },
 ]

clang/test/ClangScanDeps/modules-cas-trees-with-pch.c

@@ -191,7 +191,7 @@
 [
   {
     "directory" : "DIR",
-    "command" : "clang_tool -x c-header DIR/prefix.h -o DIR/prefix.h.pch -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
+    "command" : "clang -x c-header DIR/prefix.h -o DIR/prefix.h.pch -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
     "file" : "DIR/prefix.h"
   },
 ]
@@ -200,7 +200,7 @@
 [
   {
     "directory" : "DIR",
-    "command" : "clang_tool -fsyntax-only DIR/tu.c -include DIR/prefix.h -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
+    "command" : "clang -fsyntax-only DIR/tu.c -include DIR/prefix.h -fmodules -fimplicit-modules -fimplicit-module-maps -fmodules-cache-path=DIR/module-cache -Rcompile-job-cache",
     "file" : "DIR/tu.c"
   },
 ]

clang/test/ClangScanDeps/modules-in-stable-dirs-prefix-mapping.c

@@ -0,0 +1,94 @@
+// This test verifies modules that are entirely comprised from stable directory inputs are captured in
+// dependency information when paths are prefix mapped.
+
+// REQUIRES: shell,ondisk_cas
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/overlay.json.template > %t/overlay.json
+// RUN: sed -e "s|DIR|%/t|g" %t/compile.json.in > %t/compile.json
+
+// RUN: clang-scan-deps -compilation-database %t/compile.json \
+// RUN:   -prefix-map=%t/modules=/^modules -prefix-map=%t=/^src -prefix-map-sdk=/^sdk -prefix-map-toolchain=/^tc \
+// RUN:   -cas-path %t/cas -module-files-dir %t/modules \
+// RUN:   -j 1 -format experimental-full > %t/deps.db
+
+// RUN: cat %t/deps.db | sed 's:\\\\\?:/:g' | FileCheck %s -DPREFIX=%/t --check-prefix DEP
+
+// DEP: "is-in-stable-directories": true
+// DEP: "name": "A"
+
+// CHECK-NOT: "is-in-stable-directories": true
+// CHECK-NOT: warning:
+// CHECK-NOT: error:
+
+//--- compile.json.in
+[
+{
+    "directory": "DIR",
+    "command": "clang -x c -c DIR/client.c -isysroot DIR/MacOSX.sdk -IDIR/BuildDir -ivfsoverlay DIR/overlay.json -IDIR/MacOSX.sdk/usr/include -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-module-maps -o DIR/client.c.o",
+    "file": "DIR/client.c"
+}
+]
+
+//--- overlay.json.template
+{
+  "version": 0,
+  "case-sensitive": "false",
+  "roots": [
+    {
+          "external-contents": "DIR/BuildDir/B_vfs.h",
+          "name": "DIR/MacOSX.sdk/usr/include/B/B_vfs.h",
+          "type": "file"
+    }
+  ]
+}
+
+//--- MacOSX.sdk/usr/include/A/module.modulemap
+module A [system] {
+  umbrella "."
+}
+
+//--- MacOSX.sdk/usr/include/A/A.h
+typedef int A_type;
+
+//--- MacOSX.sdk/usr/include/B/module.modulemap
+module B [system] {
+  umbrella "."
+}
+
+//--- MacOSX.sdk/usr/include/B/B.h
+#include <B/B_vfs.h>
+
+//--- BuildDir/B_vfs.h
+typedef int local_t;
+
+//--- MacOSX.sdk/usr/include/sys/sys.h
+#include <A/A.h>
+typedef int sys_t_m;
+
+//--- MacOSX.sdk/usr/include/sys/module.modulemap
+module sys [system] {
+  umbrella "."
+}
+
+//--- MacOSX.sdk/usr/include/B_transitive/B.h
+#include <B/B.h>
+
+//--- MacOSX.sdk/usr/include/B_transitive/module.modulemap
+module B_transitive [system] {
+  umbrella "."
+}
+
+//--- MacOSX.sdk/usr/include/C/module.modulemap
+module C [system] {
+  umbrella "."
+}
+
+//--- MacOSX.sdk/usr/include/C/C.h
+#include <B_transitive/B.h>
+
+
+//--- client.c
+#include <A/A.h>
+#include <C/C.h> // This dependency transitively depends on a local header.