[clang][deps][cas] Fix include-tree contents with -working-directory

When using -working-directory we were inconsistent about using relative
or absolute paths, which was causing failures to find files in the
include-tree ft logilesystem. Now we should be consistently using the
absolute path.

Note: this changes behaviour of things like __FILE__, which would
normally have a relative path even with -working-directory. In the
future we may want to find a way to preserve the relative paths, but
that has been much harder and the current change at fixes the
compilation failures.

rdar://116135029
(cherry picked from commit 78e64df)

Author: benlangmuir

clang/lib/Tooling/DependencyScanning/IncludeTreeActionController.cpp

@@ -816,7 +816,18 @@ IncludeTreeBuilder::getObjectForBuffer(const SrcMgr::FileInfo &FI) {
 
 Expected<cas::ObjectRef>
 IncludeTreeBuilder::addToFileList(FileManager &FM, const FileEntry *FE) {
+  SmallString<128> PathStorage;
   StringRef Filename = FE->getName();
+  // Apply -working-directory to relative paths. This option causes filesystem
+  // lookups to use absolute paths, so make paths in the include-tree filesystem
+  // absolute to match.
+  if (!llvm::sys::path::is_absolute(Filename) &&
+      !FM.getFileSystemOpts().WorkingDir.empty()) {
+    PathStorage = Filename;
+    FM.FixupRelativePath(PathStorage);
+    Filename = PathStorage;
+  }
+
   llvm::ErrorOr<std::optional<cas::ObjectRef>> CASContents =
       FM.getObjectRefForFileContent(Filename);
   if (!CASContents)

clang/test/ClangScanDeps/include-tree-working-directory.c

@@ -0,0 +1,38 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/other
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-include-tree-full -cas-path %t/cas \
+// RUN:   > %t/deps.json
+
+// Build the include-tree command
+// RUN: %deps-to-rsp %t/deps.json --tu-index 0 > %t/tu.rsp
+// RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-MISS
+// RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-HIT
+// RUN: ls %t/t.o
+
+// CACHE-MISS: remark: compile job cache miss
+// CACHE-HIT: remark: compile job cache hit
+
+// RUN: cat %t/tu.rsp | sed -E 's|.*"-fcas-include-tree" "(llvmcas://[[:xdigit:]]+)".*|\1|' > %t/tu.casid
+// RUN: clang-cas-test -cas %t/cas -print-include-tree @%t/tu.casid | FileCheck %s -DPREFIX=%/t
+
+// CHECK: [[PREFIX]]/t.c llvmcas://
+// CHECK: 1:1 <built-in> llvmcas://
+// CHECK: 2:1 [[PREFIX]]/relative/h1.h llvmcas://
+// CHECK: Files:
+// CHECK: [[PREFIX]]/t.c llvmcas://
+// CHECK: [[PREFIX]]/relative/h1.h llvmcas://
+
+//--- cdb.json.template
+[{
+  "directory": "DIR/other",
+  "command": "clang -c t.c -I relative -working-directory DIR -o t.o",
+  "file": "DIR/t.c"
+}]
+
+//--- relative/h1.h
+
+//--- t.c
+#include "h1.h"

clang/test/ClangScanDeps/modules-include-tree-working-directory.c

@@ -0,0 +1,41 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/other
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-include-tree-full -cas-path %t/cas \
+// RUN:   > %t/deps.json
+
+// Build the include-tree command
+// RUN: %deps-to-rsp %t/deps.json --module H > %t/H.rsp
+// RUN: %deps-to-rsp %t/deps.json --tu-index 0 > %t/tu.rsp
+// RUN: %clang @%t/H.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-MISS
+// RUN: %clang @%t/H.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-HIT
+// RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-MISS
+// RUN: %clang @%t/tu.rsp -Rcompile-job-cache 2>&1 | FileCheck %s -check-prefix=CACHE-HIT
+
+// CACHE-MISS: remark: compile job cache miss
+// CACHE-HIT: remark: compile job cache hit
+
+// RUN: cat %t/H.rsp | sed -E 's|.*"-fcas-include-tree" "(llvmcas://[[:xdigit:]]+)".*|\1|' > %t/H.casid
+// RUN: clang-cas-test -cas %t/cas -print-include-tree @%t/H.casid | FileCheck %s -DPREFIX=%/t
+
+// CHEK:C <module-includes>
+// CHECK: 2:1 [[PREFIX]]/relative/h1.h llvmcas://
+// CHECK: Files:
+// CHECK: [[PREFIX]]/relative/h1.h llvmcas://
+
+//--- cdb.json.template
+[{
+  "directory": "DIR/other",
+  "command": "clang -fsyntax-only t.c -I relative -working-directory DIR -fmodules -fimplicit-modules -fimplicit-module-maps",
+  "file": "DIR/t.c"
+}]
+
+//--- relative/h1.h
+
+//--- relative/module.modulemap
+module H { header "h1.h" }
+
+//--- t.c
+#include "h1.h"