[clang dependency scanning] Make Current Working Directory Optimization Off by Default

[qiongsiwu]

#124786 implemented current working directory (CWD) optimization and the optimization was on by default. We have discovered that build system needs to be compatible with the CWD optimization and default off is a better behavior. The build system needs to be aware that the current working directory is ignored. Without a good way of notifying the build system, it is less risky to default to off. This PR implement the change.

rdar://145860213

[llvmbot]

@llvm/pr-subscribers-clang

Author: Qiongsi Wu (qiongsiwu)

Changes

#124786 implemented current working directory (CWD) optimization and the optimization was on by default. We have discovered that build system needs to be compatible with the CWD optimization and default off is a better behavior. The build system needs to be aware that the current working directory is ignored. Without a good way of notifying the build system, it is less risky to default to off. This PR implement the change.

rdar://145860213

---

Full diff: https://github.com/llvm/llvm-project/pull/129809.diff

3 Files Affected:

• (modified) clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h (+1-1)
• (modified) clang/test/ClangScanDeps/modules-context-hash-cwd.c (+5-5)
• (modified) clang/test/ClangScanDeps/modules-debug-dir.c (+1-1)

diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
index f002f8645d3f6..b22ba0b1c1dea 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
@@ -67,7 +67,7 @@ enum class ScanningOptimizations {
   IgnoreCWD = (1 << 4),
 
   DSS_LAST_BITMASK_ENUM(IgnoreCWD),
-  Default = All
+  Default = All & (~IgnoreCWD)
 };
 
 #undef DSS_LAST_BITMASK_ENUM
diff --git a/clang/test/ClangScanDeps/modules-context-hash-cwd.c b/clang/test/ClangScanDeps/modules-context-hash-cwd.c
index 459d2c90debe6..c609a7dcbc80e 100644
--- a/clang/test/ClangScanDeps/modules-context-hash-cwd.c
+++ b/clang/test/ClangScanDeps/modules-context-hash-cwd.c
@@ -9,14 +9,14 @@
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb3.json.in > %t/cdb3.json
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb4.json.in > %t/cdb4.json
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb5.json.in > %t/cdb5.json
-// RUN: clang-scan-deps -compilation-database %t/cdb0.json -format experimental-full > %t/result0.json
-// RUN: clang-scan-deps -compilation-database %t/cdb1.json -format experimental-full > %t/result1.json
+// RUN: clang-scan-deps -compilation-database %t/cdb0.json -format experimental-full -optimize-args=all > %t/result0.json
+// RUN: clang-scan-deps -compilation-database %t/cdb1.json -format experimental-full -optimize-args=all > %t/result1.json
 // It is not a typo to use cdb1.json for result2. We intend to use the same
 // compilation database, but different clang-scan-deps optimize-args options.
 // RUN: clang-scan-deps -compilation-database %t/cdb1.json -format experimental-full -optimize-args=header-search,system-warnings,vfs,canonicalize-macros > %t/result2.json
-// RUN: clang-scan-deps -compilation-database %t/cdb3.json -format experimental-full > %t/result3.json
-// RUN: clang-scan-deps -compilation-database %t/cdb4.json -format experimental-full > %t/result4.json
-// RUN: clang-scan-deps -compilation-database %t/cdb5.json -format experimental-full > %t/result5.json
+// RUN: clang-scan-deps -compilation-database %t/cdb3.json -format experimental-full -optimize-args=all > %t/result3.json
+// RUN: clang-scan-deps -compilation-database %t/cdb4.json -format experimental-full -optimize-args=all > %t/result4.json
+// RUN: clang-scan-deps -compilation-database %t/cdb5.json -format experimental-full -optimize-args=all > %t/result5.json
 // RUN: cat %t/result0.json %t/result1.json | FileCheck %s
 // RUN: cat %t/result0.json %t/result2.json | FileCheck %s -check-prefix=SKIPOPT
 // RUN: cat %t/result3.json %t/result4.json | FileCheck %s -check-prefix=RELPATH
diff --git a/clang/test/ClangScanDeps/modules-debug-dir.c b/clang/test/ClangScanDeps/modules-debug-dir.c
index fadec1ad52e35..c4fb4982ed791 100644
--- a/clang/test/ClangScanDeps/modules-debug-dir.c
+++ b/clang/test/ClangScanDeps/modules-debug-dir.c
@@ -4,7 +4,7 @@
 // RUN: split-file %s %t
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.in > %t/cdb.json
 // RUN: clang-scan-deps -compilation-database %t/cdb.json -format \
-// RUN:   experimental-full > %t/result.json
+// RUN:   experimental-full -optimize-args=all > %t/result.json
 // RUN: cat %t/result.json | sed 's:\\\\\?:/:g' | FileCheck %s
 
 //--- cdb.json.in

[Bigcheese]

Looks good with the added comment.

I was going to say this should also update the documentation, but we don't actually have any here. This patch doesn't need to add it, but it would be good to have some documentation on how to actually use clang-scan-deps and the scanning API.