[clang-tidy] New check: bugprone-suspicious-include

Detects and fixes suspicious code like: `#include "foo.cpp"`.

Inspired by: https://twitter.com/lefticus/status/1228458240364687360?s=20

https://reviews.llvm.org/D74669

6 files changed, 189 insertions, 4 deletions

diff --git a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
index 86936c6..9dcb315 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
@@ -45,6 +45,7 @@
 #include "StringIntegerAssignmentCheck.h"
 #include "StringLiteralWithEmbeddedNulCheck.h"
 #include "SuspiciousEnumUsageCheck.h"
+#include "SuspiciousIncludeCheck.h"
 #include "SuspiciousMemsetUsageCheck.h"
 #include "SuspiciousMissingCommaCheck.h"
 #include "SuspiciousSemicolonCheck.h"
@@ -140,6 +141,8 @@ public:
         "bugprone-string-literal-with-embedded-nul");
     CheckFactories.registerCheck<SuspiciousEnumUsageCheck>(
         "bugprone-suspicious-enum-usage");
+    CheckFactories.registerCheck<SuspiciousIncludeCheck>(
+        "bugprone-suspicious-include");
     CheckFactories.registerCheck<SuspiciousMemsetUsageCheck>(
         "bugprone-suspicious-memset-usage");
     CheckFactories.registerCheck<SuspiciousMissingCommaCheck>(
diff --git a/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt b/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
index c9078ed..a24f3bc 100644
--- a/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt
@@ -37,6 +37,7 @@ add_clang_library(clangTidyBugproneModule
   StringIntegerAssignmentCheck.cpp
   StringLiteralWithEmbeddedNulCheck.cpp
   SuspiciousEnumUsageCheck.cpp
+  SuspiciousIncludeCheck.cpp
   SuspiciousMemsetUsageCheck.cpp
   SuspiciousMissingCommaCheck.cpp
   SuspiciousSemicolonCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
new file mode 100644
index 0000000..ade7b11
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
@@ -0,0 +1,105 @@
+//===--- SuspiciousIncludeCheck.cpp - clang-tidy --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "SuspiciousIncludeCheck.h"
+#include "clang/AST/ASTContext.h"
+
+namespace clang {
+namespace tidy {
+namespace bugprone {
+
+namespace {
+class SuspiciousIncludePPCallbacks : public PPCallbacks {
+public:
+  explicit SuspiciousIncludePPCallbacks(SuspiciousIncludeCheck &Check,
+                                        const SourceManager &SM,
+                                        Preprocessor *PP)
+      : Check(Check), PP(PP) {}
+
+  void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
+                          StringRef FileName, bool IsAngled,
+                          CharSourceRange FilenameRange, const FileEntry *File,
+                          StringRef SearchPath, StringRef RelativePath,
+                          const Module *Imported,
+                          SrcMgr::CharacteristicKind FileType) override;
+
+private:
+  SuspiciousIncludeCheck &Check;
+  Preprocessor *PP;
+};
+} // namespace
+
+SuspiciousIncludeCheck::SuspiciousIncludeCheck(StringRef Name,
+                                               ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      RawStringHeaderFileExtensions(Options.getLocalOrGlobal(
+          "HeaderFileExtensions", utils::defaultHeaderFileExtensions())),
+      RawStringImplementationFileExtensions(Options.getLocalOrGlobal(
+          "ImplementationFileExtensions",
+          utils::defaultImplementationFileExtensions())) {
+  if (!utils::parseFileExtensions(RawStringImplementationFileExtensions,
+                                  ImplementationFileExtensions,
+                                  utils::defaultFileExtensionDelimiters())) {
+    llvm::errs() << "Invalid implementation file extension: "
+                 << RawStringImplementationFileExtensions << "\n";
+  }
+
+  if (!utils::parseFileExtensions(RawStringHeaderFileExtensions,
+                                  HeaderFileExtensions,
+                                  utils::defaultFileExtensionDelimiters())) {
+    llvm::errs() << "Invalid header file extension: "
+                 << RawStringHeaderFileExtensions << "\n";
+  }
+}
+
+void SuspiciousIncludeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "ImplementationFileExtensions",
+                RawStringImplementationFileExtensions);
+  Options.store(Opts, "HeaderFileExtensions", RawStringHeaderFileExtensions);
+}
+
+void SuspiciousIncludeCheck::registerPPCallbacks(
+    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+  PP->addPPCallbacks(
+      ::std::make_unique<SuspiciousIncludePPCallbacks>(*this, SM, PP));
+}
+
+void SuspiciousIncludePPCallbacks::InclusionDirective(
+    SourceLocation HashLoc, const Token &IncludeTok, StringRef FileName,
+    bool IsAngled, CharSourceRange FilenameRange, const FileEntry *File,
+    StringRef SearchPath, StringRef RelativePath, const Module *Imported,
+    SrcMgr::CharacteristicKind FileType) {
+  SourceLocation DiagLoc = FilenameRange.getBegin().getLocWithOffset(1);
+
+  const Optional<StringRef> IFE =
+      utils::getFileExtension(FileName, Check.ImplementationFileExtensions);
+  if (!IFE)
+    return;
+
+  Check.diag(DiagLoc, "suspicious #%0 of file with '%1' extension")
+      << IncludeTok.getIdentifierInfo()->getName() << *IFE;
+
+  for (const auto &HFE : Check.HeaderFileExtensions) {
+    SmallString<128> GuessedFileName(FileName);
+    llvm::sys::path::replace_extension(GuessedFileName,
+                                       (HFE.size() ? "." : "") + HFE);
+
+    const DirectoryLookup *CurDir;
+    Optional<FileEntryRef> File =
+        PP->LookupFile(DiagLoc, GuessedFileName, IsAngled, nullptr, nullptr,
+                       CurDir, nullptr, nullptr, nullptr, nullptr, nullptr);
+    if (File) {
+      Check.diag(DiagLoc, "did you mean to include '%0'?", DiagnosticIDs::Note)
+          << GuessedFileName;
+    }
+  }
+}
+
+} // namespace bugprone
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.h b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.h
new file mode 100644
index 0000000..674292d
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.h
@@ -0,0 +1,57 @@
+//===--- SuspiciousIncludeCheck.h - clang-tidy ------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_SUSPICIOUSINCLUDECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_SUSPICIOUSINCLUDECHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "../utils/FileExtensionsUtils.h"
+
+namespace clang {
+namespace tidy {
+namespace bugprone {
+
+/// Warns on inclusion of files whose names suggest that they're implementation
+/// files, instead of headers. E.g:
+///
+///     #include "foo.cpp"  // warning
+///     #include "bar.c"    // warning
+///     #include "baz.h"    // no diagnostic
+///
+/// The check supports these options:
+///   - `HeaderFileExtensions`: a semicolon-separated list of filename
+///     extensions of header files (The filename extensions should not contain
+///     "." prefix) ";h;hh;hpp;hxx" by default. For extension-less header
+///     files, using an empty string or leaving an empty string between ";" if
+///     there are other filename extensions.
+///
+///   - `ImplementationFileExtensions`: likewise, a semicolon-separated list of
+///     filename extensions of implementation files. "c;cc;cpp;cxx" by default.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone-suspicious-include.html
+class SuspiciousIncludeCheck : public ClangTidyCheck {
+public:
+  SuspiciousIncludeCheck(StringRef Name, ClangTidyContext *Context);
+  void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+                           Preprocessor *ModuleExpanderPP) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+  utils::FileExtensionsSet HeaderFileExtensions;
+  utils::FileExtensionsSet ImplementationFileExtensions;
+
+private:
+  const std::string RawStringHeaderFileExtensions;
+  const std::string RawStringImplementationFileExtensions;
+};
+
+} // namespace bugprone
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_SUSPICIOUSINCLUDECHECK_H
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
index d6f4b2a..4eaf8bc 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
@@ -53,13 +53,20 @@ bool parseFileExtensions(StringRef AllFileExtensions,
   return true;
 }
 
-bool isFileExtension(StringRef FileName,
-                     const FileExtensionsSet &FileExtensions) {
+llvm::Optional<StringRef>
+getFileExtension(StringRef FileName, const FileExtensionsSet &FileExtensions) {
   StringRef Extension = llvm::sys::path::extension(FileName);
   if (Extension.empty())
-    return false;
+    return llvm::None;
   // Skip "." prefix.
-  return FileExtensions.count(Extension.substr(1)) > 0;
+  if (!FileExtensions.count(Extension.substr(1)))
+    return llvm::None;
+  return Extension;
+}
+
+bool isFileExtension(StringRef FileName,
+                     const FileExtensionsSet &FileExtensions) {
+  return getFileExtension(FileName, FileExtensions).hasValue();
 }
 
 } // namespace utils
diff --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
index 43fc573..e5dfae1 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.h
@@ -11,6 +11,7 @@
 
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringRef.h"
 
@@ -36,6 +37,12 @@ bool isSpellingLocInHeaderFile(SourceLocation Loc, SourceManager &SM,
 /// extensions.
 inline StringRef defaultHeaderFileExtensions() { return ";h;hh;hpp;hxx"; }
 
+/// Returns recommended default value for the list of implementaiton file
+/// extensions.
+inline StringRef defaultImplementationFileExtensions() {
+  return "c;cc;cpp;cxx";
+}
+
 /// Returns recommended default value for the list of file extension
 /// delimiters.
 inline StringRef defaultFileExtensionDelimiters() { return ",;"; }
@@ -45,6 +52,11 @@ bool parseFileExtensions(StringRef AllFileExtensions,
                          FileExtensionsSet &FileExtensions,
                          StringRef Delimiters);
 
+/// Decides whether a file has a header file extension.
+/// Returns the file extension, if included in the provided set.
+llvm::Optional<StringRef>
+getFileExtension(StringRef FileName, const FileExtensionsSet &FileExtensions);
+
 /// Decides whether a file has one of the specified file extensions.
 bool isFileExtension(StringRef FileName,
                      const FileExtensionsSet &FileExtensions);