Reland [clang] Canonicalize system headers in dependency file when -canonical-prefixes

Clang was writing paths to the dependency file that don't exist when using a sysroot with symlinks, causing everything to get rebuilt every time. This is reproducible on Linux by creating a symlink to '/', using that as the sysroot, and trying to build something with ninja that includes the C++ stdlib (e.g. a typical build of LLVM).

This fixes https://github.com/ninja-build/ninja/issues/1330 and somewhat matches gcc.

gcc canonicalizes system headers in dependency files under a -f[no-]canonical-system-headers, but it makes more sense to look at -canonical-prefixes.

D37954 was a previous attempt at this.

Fixed use of %T instead of %t in test, causing bots to fail the test on the initial commit.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D149187

1 files changed, 35 insertions, 15 deletions

diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
index fe4218b..44268e7 100644
--- a/clang/lib/Frontend/DependencyFile.cpp
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -49,6 +49,7 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
       DepCollector.maybeAddDependency(
           llvm::sys::path::remove_leading_dotslash(*Filename),
           /*FromModule*/ false, isSystem(FileType), /*IsModuleFile*/ false,
+          &PP.getFileManager(),
           /*IsMissing*/ false);
   }
 
@@ -56,9 +57,11 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
                    SrcMgr::CharacteristicKind FileType) override {
     StringRef Filename =
         llvm::sys::path::remove_leading_dotslash(SkippedFile.getName());
-    DepCollector.maybeAddDependency(Filename, /*FromModule=*/false,
+    DepCollector.maybeAddDependency(Filename,
+                                    /*FromModule=*/false,
                                     /*IsSystem=*/isSystem(FileType),
                                     /*IsModuleFile=*/false,
+                                    &PP.getFileManager(),
                                     /*IsMissing=*/false);
   }
 
@@ -69,9 +72,12 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
                           StringRef RelativePath, const Module *Imported,
                           SrcMgr::CharacteristicKind FileType) override {
     if (!File)
-      DepCollector.maybeAddDependency(FileName, /*FromModule*/false,
-                                     /*IsSystem*/false, /*IsModuleFile*/false,
-                                     /*IsMissing*/true);
+      DepCollector.maybeAddDependency(FileName,
+                                      /*FromModule*/ false,
+                                      /*IsSystem*/ false,
+                                      /*IsModuleFile*/ false,
+                                      &PP.getFileManager(),
+                                      /*IsMissing*/ true);
     // Files that actually exist are handled by FileChanged.
   }
 
@@ -82,9 +88,11 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
       return;
     StringRef Filename =
         llvm::sys::path::remove_leading_dotslash(File->getName());
-    DepCollector.maybeAddDependency(Filename, /*FromModule=*/false,
+    DepCollector.maybeAddDependency(Filename,
+                                    /*FromModule=*/false,
                                     /*IsSystem=*/isSystem(FileType),
                                     /*IsModuleFile=*/false,
+                                    &PP.getFileManager(),
                                     /*IsMissing=*/false);
   }
 
@@ -100,10 +108,12 @@ struct DepCollectorMMCallbacks : public ModuleMapCallbacks {
   void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry,
                          bool IsSystem) override {
     StringRef Filename = Entry.getName();
-    DepCollector.maybeAddDependency(Filename, /*FromModule*/false,
-                                    /*IsSystem*/IsSystem,
-                                    /*IsModuleFile*/false,
-                                    /*IsMissing*/false);
+    DepCollector.maybeAddDependency(Filename,
+                                    /*FromModule*/ false,
+                                    /*IsSystem*/ IsSystem,
+                                    /*IsModuleFile*/ false,
+                                    /*FileMgr*/ nullptr,
+                                    /*IsMissing*/ false);
   }
 };
 
@@ -118,9 +128,11 @@ struct DepCollectorASTListener : public ASTReaderListener {
   }
   void visitModuleFile(StringRef Filename,
                        serialization::ModuleKind Kind) override {
-    DepCollector.maybeAddDependency(Filename, /*FromModule*/true,
-                                   /*IsSystem*/false, /*IsModuleFile*/true,
-                                   /*IsMissing*/false);
+    DepCollector.maybeAddDependency(Filename,
+                                    /*FromModule*/ true,
+                                    /*IsSystem*/ false, /*IsModuleFile*/ true,
+                                    /*FileMgr*/ nullptr,
+                                    /*IsMissing*/ false);
   }
   bool visitInputFile(StringRef Filename, bool IsSystem,
                       bool IsOverridden, bool IsExplicitModule) override {
@@ -132,8 +144,9 @@ struct DepCollectorASTListener : public ASTReaderListener {
     if (auto FE = FileMgr.getOptionalFileRef(Filename))
       Filename = FE->getName();
 
-    DepCollector.maybeAddDependency(Filename, /*FromModule*/true, IsSystem,
-                                   /*IsModuleFile*/false, /*IsMissing*/false);
+    DepCollector.maybeAddDependency(Filename, /*FromModule*/ true, IsSystem,
+                                    /*IsModuleFile*/ false, /*FileMgr*/ nullptr,
+                                    /*IsMissing*/ false);
     return true;
   }
 };
@@ -142,9 +155,15 @@ struct DepCollectorASTListener : public ASTReaderListener {
 void DependencyCollector::maybeAddDependency(StringRef Filename,
                                              bool FromModule, bool IsSystem,
                                              bool IsModuleFile,
+                                             FileManager *FileMgr,
                                              bool IsMissing) {
-  if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing))
+  if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing)) {
+    if (IsSystem && FileMgr && shouldCanonicalizeSystemDependencies()) {
+      if (auto F = FileMgr->getFile(Filename))
+        Filename = FileMgr->getCanonicalName(*F);
+    }
     addDependency(Filename);
+  }
 }
 
 bool DependencyCollector::addDependency(StringRef Filename) {
@@ -192,6 +211,7 @@ DependencyFileGenerator::DependencyFileGenerator(
     const DependencyOutputOptions &Opts)
     : OutputFile(Opts.OutputFile), Targets(Opts.Targets),
       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
+      CanonicalSystemHeaders(Opts.CanonicalSystemHeaders),
       PhonyTarget(Opts.UsePhonyTargets),
       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps), SeenMissingHeader(false),
       IncludeModuleFiles(Opts.IncludeModuleFiles),