[include-cleaner] Unify symlink handling (llvm#102615)

We were using tryGetRealPathName in certain places, which resolves
symlinks (sometimes). This was resulting in discrepancies in behavior,
depending on how a file was first reached.

This path migrates all usages of tryGetRealPathName to regular getName
instead.

This implies one backward incompatible change for header-filtering. Our
ignore-header option used to filter against suffixes of absolute paths,
whereas now filter can receive working-directory relative paths in some
cases, possibly braking existing filters.
Chances of really braking users is pretty low:
- We'll still filter against absolute paths when header is outside the
  working directory (e.g. /usr/bin/include/some/linux/header.h.)
- Most projects run builds in a working directory that's nested inside
  the repository, hence relative paths still contain all the segments
  relative to repository root and anything else is unlikely to be
  meaningful. e.g. if a header is in
  `$HOME/work/llvm-project/clang-tools-extra/header.h` with builds being
  run in `$home/work/llvm-project/build`, we'll still filter against
  `../clang-tools-extra/header.h` which has all the useful segments as a
  suffix.
- This is also a change in how we handle symlinks, but this is aligned
  with what we do in rest of our tools (clangd, tidy checks etc.). We
  tend to not resolve any symlinks for the file.

clang-tools-extra/include-cleaner/include/clang-include-cleaner/Types.h

@@ -136,8 +136,8 @@ struct Header {
   }
   StringRef verbatim() const { return std::get<Verbatim>(Storage); }
 
-  /// Absolute path for the header when it's a physical file. Otherwise just
-  /// the spelling without surrounding quotes/brackets.
+  /// For phiscal files, either absolute path or path relative to the execution
+  /// root. Otherwise just the spelling without surrounding quotes/brackets.
   llvm::StringRef resolvedPath() const;
 
 private:

clang-tools-extra/include-cleaner/lib/Analysis.cpp

@@ -82,7 +82,7 @@ analyze(llvm::ArrayRef<Decl *> ASTRoots,
         const PragmaIncludes *PI, const Preprocessor &PP,
         llvm::function_ref<bool(llvm::StringRef)> HeaderFilter) {
   auto &SM = PP.getSourceManager();
-  const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID());
+  const auto MainFile = *SM.getFileEntryRefForID(SM.getMainFileID());
   llvm::DenseSet<const Include *> Used;
   llvm::StringSet<> Missing;
   if (!HeaderFilter)
@@ -95,37 +95,38 @@ analyze(llvm::ArrayRef<Decl *> ASTRoots,
              for (const Header &H : Providers) {
                if (H.kind() == Header::Physical &&
                    (H.physical() == MainFile ||
-                    (ResourceDir && H.physical().getDir() == *ResourceDir))) {
+                    H.physical().getDir() == ResourceDir)) {
                  Satisfied = true;
                }
                for (const Include *I : Inc.match(H)) {
                  Used.insert(I);
                  Satisfied = true;
                }
              }
-             if (!Satisfied && !Providers.empty() &&
-                 Ref.RT == RefType::Explicit &&
-                 !HeaderFilter(Providers.front().resolvedPath())) {
-               // Check if we have any headers with the same spelling, in edge
-               // cases like `#include_next "foo.h"`, the user can't ever
-               // include the physical foo.h, but can have a spelling that
-               // refers to it.
-               auto Spelling = spellHeader(
-                   {Providers.front(), PP.getHeaderSearchInfo(), MainFile});
-               for (const Include *I : Inc.match(Header{Spelling})) {
-                 Used.insert(I);
-                 Satisfied = true;
-               }
-               if (!Satisfied)
-                 Missing.insert(std::move(Spelling));
+             // Bail out if we can't (or need not) insert an include.
+             if (Satisfied || Providers.empty() || Ref.RT != RefType::Explicit)
+               return;
+             if (HeaderFilter(Providers.front().resolvedPath()))
+               return;
+             // Check if we have any headers with the same spelling, in edge
+             // cases like `#include_next "foo.h"`, the user can't ever
+             // include the physical foo.h, but can have a spelling that
+             // refers to it.
+             auto Spelling = spellHeader(
+                 {Providers.front(), PP.getHeaderSearchInfo(), MainFile});
+             for (const Include *I : Inc.match(Header{Spelling})) {
+               Used.insert(I);
+               Satisfied = true;
              }
+             if (!Satisfied)
+               Missing.insert(std::move(Spelling));
            });
 
   AnalysisResults Results;
   for (const Include &I : Inc.all()) {
     if (Used.contains(&I) || !I.Resolved ||
-        HeaderFilter(I.Resolved->getFileEntry().tryGetRealPathName()) ||
-        (ResourceDir && I.Resolved->getFileEntry().getDir() == *ResourceDir))
+        HeaderFilter(I.Resolved->getName()) ||
+        I.Resolved->getDir() == ResourceDir)
       continue;
     if (PI) {
       if (PI->shouldKeep(*I.Resolved))
@@ -137,7 +138,7 @@ analyze(llvm::ArrayRef<Decl *> ASTRoots,
         // Since most private -> public mappings happen in a verbatim way, we
         // check textually here. This might go wrong in presence of symlinks or
         // header mappings. But that's not different than rest of the places.
-        if (MainFile->tryGetRealPathName().ends_with(PHeader))
+        if (MainFile.getName().ends_with(PHeader))
           continue;
       }
     }

clang-tools-extra/include-cleaner/lib/HTMLReport.cpp

@@ -14,6 +14,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "AnalysisInternal.h"
+#include "clang-include-cleaner/IncludeSpeller.h"
 #include "clang-include-cleaner/Types.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/PrettyPrinter.h"
@@ -167,22 +168,6 @@ class Reporter {
     return "semiused";
   }
 
-  std::string spellHeader(const Header &H) {
-    switch (H.kind()) {
-    case Header::Physical: {
-      bool IsAngled = false;
-      std::string Path = HS.suggestPathToFileForDiagnostics(
-          H.physical(), MainFE->tryGetRealPathName(), &IsAngled);
-      return IsAngled ? "<" + Path + ">" : "\"" + Path + "\"";
-    }
-    case Header::Standard:
-      return H.standard().name().str();
-    case Header::Verbatim:
-      return H.verbatim().str();
-    }
-    llvm_unreachable("Unknown Header kind");
-  }
-
   void fillTarget(Ref &R) {
     // Duplicates logic from walkUsed(), which doesn't expose SymbolLocations.
     for (auto &Loc : locateSymbol(R.Sym))
@@ -204,7 +189,7 @@ class Reporter {
                      R.Includes.end());
 
     if (!R.Headers.empty())
-      R.Insert = spellHeader(R.Headers.front());
+      R.Insert = spellHeader({R.Headers.front(), HS, MainFE});
   }
 
 public:

clang-tools-extra/include-cleaner/lib/Types.cpp

@@ -10,7 +10,6 @@
 #include "TypesInternal.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/FileEntry.h"
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
@@ -48,7 +47,7 @@ llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Symbol &S) {
 llvm::StringRef Header::resolvedPath() const {
   switch (kind()) {
   case include_cleaner::Header::Physical:
-    return physical().getFileEntry().tryGetRealPathName();
+    return physical().getName();
   case include_cleaner::Header::Standard:
     return standard().name().trim("<>\"");
   case include_cleaner::Header::Verbatim:

clang-tools-extra/include-cleaner/tool/IncludeCleaner.cpp

@@ -164,7 +164,7 @@ class Action : public clang::ASTFrontendAction {
       writeHTML();
 
     llvm::StringRef Path =
-        SM.getFileEntryForID(SM.getMainFileID())->tryGetRealPathName();
+        SM.getFileEntryRefForID(SM.getMainFileID())->getName();
     assert(!Path.empty() && "Main file path not known?");
     llvm::StringRef Code = SM.getBufferData(SM.getMainFileID());
 

clang-tools-extra/include-cleaner/unittests/AnalysisTest.cpp

@@ -22,9 +22,12 @@
 #include "clang/Testing/TestAST.h"
 #include "clang/Tooling/Inclusions/StandardLibrary.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/ScopedPrinter.h"
+#include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Testing/Annotations/Annotations.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -204,21 +207,37 @@ class AnalyzeTest : public testing::Test {
   TestInputs Inputs;
   PragmaIncludes PI;
   RecordedPP PP;
+  llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> ExtraFS = nullptr;
+
   AnalyzeTest() {
     Inputs.MakeAction = [this] {
       struct Hook : public SyntaxOnlyAction {
       public:
-        Hook(RecordedPP &PP, PragmaIncludes &PI) : PP(PP), PI(PI) {}
+        Hook(RecordedPP &PP, PragmaIncludes &PI,
+             llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> ExtraFS)
+            : PP(PP), PI(PI), ExtraFS(std::move(ExtraFS)) {}
         bool BeginSourceFileAction(clang::CompilerInstance &CI) override {
           CI.getPreprocessor().addPPCallbacks(PP.record(CI.getPreprocessor()));
           PI.record(CI);
           return true;
         }
 
+        bool BeginInvocation(CompilerInstance &CI) override {
+          if (!ExtraFS)
+            return true;
+          auto OverlayFS =
+              llvm::makeIntrusiveRefCnt<llvm::vfs::OverlayFileSystem>(
+                  CI.getFileManager().getVirtualFileSystemPtr());
+          OverlayFS->pushOverlay(ExtraFS);
+          CI.getFileManager().setVirtualFileSystem(std::move(OverlayFS));
+          return true;
+        }
+
         RecordedPP &PP;
         PragmaIncludes &PI;
+        llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> ExtraFS;
       };
-      return std::make_unique<Hook>(PP, PI);
+      return std::make_unique<Hook>(PP, PI, ExtraFS);
     };
   }
 };
@@ -322,6 +341,58 @@ TEST_F(AnalyzeTest, DifferentHeaderSameSpelling) {
   EXPECT_THAT(Results.Missing, testing::IsEmpty());
 }
 
+TEST_F(AnalyzeTest, SpellingIncludesWithSymlinks) {
+  llvm::Annotations Code(R"cpp(
+  #include "header.h"
+  void $bar^bar() {
+    $foo^foo();
+  }
+  )cpp");
+  Inputs.Code = Code.code();
+  ExtraFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
+  ExtraFS->addFile("content_for/0", /*ModificationTime=*/{},
+                   llvm::MemoryBuffer::getMemBufferCopy(guard(R"cpp(
+  #include "inner.h"
+  )cpp")));
+  ExtraFS->addSymbolicLink("header.h", "content_for/0",
+                           /*ModificationTime=*/{});
+  ExtraFS->addFile("content_for/1", /*ModificationTime=*/{},
+                   llvm::MemoryBuffer::getMemBufferCopy(guard(R"cpp(
+  void foo();
+  )cpp")));
+  ExtraFS->addSymbolicLink("inner.h", "content_for/1",
+                           /*ModificationTime=*/{});
+
+  TestAST AST(Inputs);
+  std::vector<Decl *> DeclsInTU;
+  for (auto *D : AST.context().getTranslationUnitDecl()->decls())
+    DeclsInTU.push_back(D);
+  auto Results = analyze(DeclsInTU, {}, PP.Includes, &PI, AST.preprocessor());
+  // Check that we're spelling header using the symlink, and not underlying
+  // path.
+  EXPECT_THAT(Results.Missing, testing::ElementsAre("\"inner.h\""));
+  // header.h should be unused.
+  EXPECT_THAT(Results.Unused, Not(testing::IsEmpty()));
+
+  {
+    // Make sure filtering is also applied to symlink, not underlying file.
+    auto HeaderFilter = [](llvm::StringRef Path) { return Path == "inner.h"; };
+    Results = analyze(DeclsInTU, {}, PP.Includes, &PI, AST.preprocessor(),
+                      HeaderFilter);
+    EXPECT_THAT(Results.Missing, testing::ElementsAre("\"inner.h\""));
+    // header.h should be unused.
+    EXPECT_THAT(Results.Unused, Not(testing::IsEmpty()));
+  }
+  {
+    auto HeaderFilter = [](llvm::StringRef Path) { return Path == "header.h"; };
+    Results = analyze(DeclsInTU, {}, PP.Includes, &PI, AST.preprocessor(),
+                      HeaderFilter);
+    // header.h should be ignored now.
+    EXPECT_THAT(Results.Unused, Not(testing::IsEmpty()));
+    EXPECT_THAT(Results.Missing, testing::ElementsAre("\"inner.h\""));
+  }
+}
+
 TEST(FixIncludes, Basic) {
   llvm::StringRef Code = R"cpp(#include "d.h"
 #include "a.h"

clang-tools-extra/include-cleaner/unittests/IncludeSpellerTest.cpp

@@ -47,8 +47,7 @@ class DummyIncludeSpeller : public IncludeSpeller {
       return "<bits/stdc++.h>";
     if (Input.H.kind() != Header::Physical)
       return "";
-    llvm::StringRef AbsolutePath =
-        Input.H.physical().getFileEntry().tryGetRealPathName();
+    llvm::StringRef AbsolutePath = Input.H.resolvedPath();
     std::string RootWithSeparator{testRoot()};
     RootWithSeparator += llvm::sys::path::get_separator();
     if (!AbsolutePath.consume_front(llvm::StringRef{RootWithSeparator}))

clang-tools-extra/include-cleaner/unittests/RecordTest.cpp

@@ -53,9 +53,11 @@ MATCHER_P(named, N, "") {
 }
 
 MATCHER_P(FileNamed, N, "") {
-  if (arg.getFileEntry().tryGetRealPathName() == N)
+  llvm::StringRef ActualName = arg.getName();
+  ActualName.consume_front("./");
+  if (ActualName == N)
     return true;
-  *result_listener << arg.getFileEntry().tryGetRealPathName().str();
+  *result_listener << ActualName.str();
   return false;
 }