Add support for `NOLINTBEGIN` ... `NOLINTEND` comments

Add support for NOLINTBEGIN ... NOLINTEND comments to suppress
clang-tidy warnings over multiple lines. All lines between the "begin"
and "end" markers are suppressed.

Example:

// NOLINTBEGIN(some-check)
<Code with warnings to be suppressed, line 1>
<Code with warnings to be suppressed, line 2>
<Code with warnings to be suppressed, line 3>
// NOLINTEND(some-check)
Follows similar syntax as the NOLINT and NOLINTNEXTLINE comments
that are already implemented, i.e. allows multiple checks to be provided
in parentheses; suppresses all checks if the parentheses are omitted,
etc.

If the comments are misused, e.g. using a NOLINTBEGIN but not
terminating it with a NOLINTEND, a clang-tidy-nolint diagnostic
message pointing to the misuse is generated.

As part of implementing this feature, the following bugs were fixed in
existing code:

IsNOLINTFound(): IsNOLINTFound("NOLINT", Str) returns true when Str is
"NOLINTNEXTLINE". This is because the textual search finds NOLINT as
the stem of NOLINTNEXTLINE.

LineIsMarkedWithNOLINT(): NOLINTNEXTLINEs on the very first line of a
file are ignored. This is due to rsplit('\n\').second returning a blank
string when there are no more newline chars to split on.

clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp

@@ -23,6 +23,7 @@
 #include "clang/AST/Attr.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Frontend/DiagnosticRenderer.h"
 #include "clang/Lex/Lexer.h"
@@ -202,6 +203,17 @@ DiagnosticBuilder ClangTidyContext::diag(
   return DiagEngine->Report(ID);
 }
 
+DiagnosticBuilder ClangTidyContext::diag(const ClangTidyError &Error) {
+  SourceManager &SM = DiagEngine->getSourceManager();
+  llvm::ErrorOr<const FileEntry *> File =
+      SM.getFileManager().getFile(Error.Message.FilePath);
+  FileID ID = SM.getOrCreateFileID(*File, SrcMgr::C_User);
+  SourceLocation FileStartLoc = SM.getLocForStartOfFile(ID);
+  SourceLocation Loc = FileStartLoc.getLocWithOffset(Error.Message.FileOffset);
+  return diag(Error.DiagnosticName, Loc, Error.Message.Message,
+              static_cast<DiagnosticIDs::Level>(Error.DiagLevel));
+}
+
 DiagnosticBuilder ClangTidyContext::configurationDiag(
     StringRef Message,
     DiagnosticIDs::Level Level /* = DiagnosticIDs::Warning*/) {
@@ -307,14 +319,26 @@ void ClangTidyDiagnosticConsumer::finalizeLastError() {
   LastErrorPassesLineFilter = false;
 }
 
-static bool IsNOLINTFound(StringRef NolintDirectiveText, StringRef Line,
-                          unsigned DiagID, const ClangTidyContext &Context) {
-  const size_t NolintIndex = Line.find(NolintDirectiveText);
+static bool isNOLINTFound(StringRef NolintDirectiveText, StringRef CheckName,
+                          StringRef Line, size_t *FoundNolintIndex = nullptr,
+                          bool *SuppressionIsSpecific = nullptr) {
+  if (FoundNolintIndex)
+    *FoundNolintIndex = StringRef::npos;
+  if (SuppressionIsSpecific)
+    *SuppressionIsSpecific = false;
+
+  size_t NolintIndex = Line.find(NolintDirectiveText);
   if (NolintIndex == StringRef::npos)
     return false;
 
   size_t BracketIndex = NolintIndex + NolintDirectiveText.size();
-  // Check if the specific checks are specified in brackets.
+  if (BracketIndex < Line.size() && isalnum(Line[BracketIndex])) {
+    // Reject this search result, otherwise it will cause false positives when
+    // NOLINT is found as a substring of NOLINT(NEXTLINE/BEGIN/END).
+    return false;
+  }
+
+  // Check if specific checks are specified in brackets.
   if (BracketIndex < Line.size() && Line[BracketIndex] == '(') {
     ++BracketIndex;
     const size_t BracketEndIndex = Line.find(')', BracketIndex);
@@ -323,16 +347,22 @@ static bool IsNOLINTFound(StringRef NolintDirectiveText, StringRef Line,
           Line.substr(BracketIndex, BracketEndIndex - BracketIndex);
       // Allow disabling all the checks with "*".
       if (ChecksStr != "*") {
-        std::string CheckName = Context.getCheckName(DiagID);
         // Allow specifying a few check names, delimited with comma.
         SmallVector<StringRef, 1> Checks;
         ChecksStr.split(Checks, ',', -1, false);
         llvm::transform(Checks, Checks.begin(),
                         [](StringRef S) { return S.trim(); });
-        return llvm::find(Checks, CheckName) != Checks.end();
+        if (llvm::find(Checks, CheckName) == Checks.end())
+          return false;
+        if (SuppressionIsSpecific)
+          *SuppressionIsSpecific = true;
       }
     }
   }
+
+  if (FoundNolintIndex)
+    *FoundNolintIndex = NolintIndex;
+
   return true;
 }
 
@@ -342,34 +372,154 @@ static llvm::Optional<StringRef> getBuffer(const SourceManager &SM, FileID File,
                  : SM.getBufferDataIfLoaded(File);
 }
 
-static bool LineIsMarkedWithNOLINT(const SourceManager &SM, SourceLocation Loc,
-                                   unsigned DiagID,
-                                   const ClangTidyContext &Context,
-                                   bool AllowIO) {
+static ClangTidyError createNolintError(const ClangTidyContext &Context,
+                                        const SourceManager &SM,
+                                        SourceLocation Loc,
+                                        bool IsNolintBegin) {
+  ClangTidyError Error("clang-tidy-nolint", ClangTidyError::Error,
+                       Context.getCurrentBuildDirectory(), false);
+  StringRef Message =
+      IsNolintBegin
+          ? "unmatched 'NOLINTBEGIN' comment without a subsequent 'NOLINTEND' "
+            "comment"
+          : "unmatched 'NOLINTEND' comment without a previous 'NOLINTBEGIN' "
+            "comment";
+  Error.Message = tooling::DiagnosticMessage(Message, SM, Loc);
+  return Error;
+}
+
+static Optional<ClangTidyError>
+tallyNolintBegins(const ClangTidyContext &Context, const SourceManager &SM,
+                  StringRef CheckName, SmallVector<StringRef> Lines,
+                  SourceLocation LinesLoc,
+                  SmallVector<SourceLocation> &SpecificNolintBegins,
+                  SmallVector<SourceLocation> &GlobalNolintBegins) {
+  // Keep a running total of how many NOLINT(BEGIN...END) blocks are active.
+  size_t NolintIndex;
+  bool SuppressionIsSpecific;
+  auto List = [&]() -> SmallVector<SourceLocation> * {
+    return SuppressionIsSpecific ? &SpecificNolintBegins : &GlobalNolintBegins;
+  };
+  for (const auto &Line : Lines) {
+    if (isNOLINTFound("NOLINTBEGIN", CheckName, Line, &NolintIndex,
+                      &SuppressionIsSpecific)) {
+      // Check if a new block is being started.
+      List()->emplace_back(LinesLoc.getLocWithOffset(NolintIndex));
+    } else if (isNOLINTFound("NOLINTEND", CheckName, Line, &NolintIndex,
+                             &SuppressionIsSpecific)) {
+      // Check if the previous block is being closed.
+      if (!List()->empty()) {
+        List()->pop_back();
+      } else {
+        // Trying to close a nonexistent block. Return a diagnostic about this
+        // misuse that can be displayed along with the original clang-tidy check
+        // that the user was attempting to suppress.
+        return createNolintError(Context, SM,
+                                 LinesLoc.getLocWithOffset(NolintIndex), false);
+      }
+    }
+    // Advance source location to the next line.
+    LinesLoc = LinesLoc.getLocWithOffset(Line.size() + sizeof('\n'));
+  }
+  return None; // All NOLINT(BEGIN/END) use has been consistent so far.
+}
+
+static bool
+lineIsWithinNolintBegin(const ClangTidyContext &Context,
+                        SmallVectorImpl<ClangTidyError> &SuppressionErrors,
+                        const SourceManager &SM, SourceLocation Loc,
+                        StringRef CheckName, StringRef TextBeforeDiag,
+                        StringRef TextAfterDiag) {
+  Loc = SM.getExpansionRange(Loc).getBegin();
+  SourceLocation FileStartLoc = SM.getLocForStartOfFile(SM.getFileID(Loc));
+
+  // Check if there's an open NOLINT(BEGIN...END) block on the previous lines.
+  SmallVector<StringRef> PrevLines;
+  TextBeforeDiag.split(PrevLines, '\n');
+  SmallVector<SourceLocation> SpecificNolintBegins;
+  SmallVector<SourceLocation> GlobalNolintBegins;
+  auto Error =
+      tallyNolintBegins(Context, SM, CheckName, PrevLines, FileStartLoc,
+                        SpecificNolintBegins, GlobalNolintBegins);
+  if (Error) {
+    SuppressionErrors.emplace_back(Error.getValue());
+    return false;
+  }
+  bool WithinNolintBegin =
+      !SpecificNolintBegins.empty() || !GlobalNolintBegins.empty();
+
+  // Check that every block is terminated correctly on the following lines.
+  SmallVector<StringRef> FollowingLines;
+  TextAfterDiag.split(FollowingLines, '\n');
+  Error = tallyNolintBegins(Context, SM, CheckName, FollowingLines, Loc,
+                            SpecificNolintBegins, GlobalNolintBegins);
+  if (Error) {
+    SuppressionErrors.emplace_back(Error.getValue());
+    return false;
+  }
+
+  // The following blocks were never closed. Return diagnostics for each
+  // instance that can be displayed along with the original clang-tidy check
+  // that the user was attempting to suppress.
+  for (const auto NolintBegin : SpecificNolintBegins) {
+    auto Error = createNolintError(Context, SM, NolintBegin, true);
+    SuppressionErrors.emplace_back(Error);
+  }
+  for (const auto NolintBegin : GlobalNolintBegins) {
+    auto Error = createNolintError(Context, SM, NolintBegin, true);
+    SuppressionErrors.emplace_back(Error);
+  }
+
+  return WithinNolintBegin && SuppressionErrors.empty();
+}
+
+static bool
+lineIsMarkedWithNOLINT(const ClangTidyContext &Context,
+                       SmallVectorImpl<ClangTidyError> &SuppressionErrors,
+                       bool AllowIO, const SourceManager &SM,
+                       SourceLocation Loc, StringRef CheckName) {
+  // Get source code for this location.
   FileID File;
   unsigned Offset;
   std::tie(File, Offset) = SM.getDecomposedSpellingLoc(Loc);
-  llvm::Optional<StringRef> Buffer = getBuffer(SM, File, AllowIO);
+  Optional<StringRef> Buffer = getBuffer(SM, File, AllowIO);
   if (!Buffer)
     return false;
 
   // Check if there's a NOLINT on this line.
-  StringRef RestOfLine = Buffer->substr(Offset).split('\n').first;
-  if (IsNOLINTFound("NOLINT", RestOfLine, DiagID, Context))
+  StringRef TextAfterDiag = Buffer->substr(Offset);
+  StringRef RestOfThisLine, FollowingLines;
+  std::tie(RestOfThisLine, FollowingLines) = TextAfterDiag.split('\n');
+  if (isNOLINTFound("NOLINT", CheckName, RestOfThisLine))
     return true;
 
   // Check if there's a NOLINTNEXTLINE on the previous line.
-  StringRef PrevLine =
-      Buffer->substr(0, Offset).rsplit('\n').first.rsplit('\n').second;
-  return IsNOLINTFound("NOLINTNEXTLINE", PrevLine, DiagID, Context);
+  StringRef TextBeforeDiag = Buffer->substr(0, Offset);
+  size_t LastNewLinePos = TextBeforeDiag.rfind('\n');
+  StringRef PrevLines = (LastNewLinePos == StringRef::npos)
+                            ? StringRef()
+                            : TextBeforeDiag.slice(0, LastNewLinePos);
+  LastNewLinePos = PrevLines.rfind('\n');
+  StringRef PrevLine = (LastNewLinePos == StringRef::npos)
+                           ? PrevLines
+                           : PrevLines.substr(LastNewLinePos + 1);
+  if (isNOLINTFound("NOLINTNEXTLINE", CheckName, PrevLine))
+    return true;
+
+  // Check if this line is within a NOLINT(BEGIN...END) block.
+  return lineIsWithinNolintBegin(Context, SuppressionErrors, SM, Loc, CheckName,
+                                 TextBeforeDiag, TextAfterDiag);
 }
 
-static bool LineIsMarkedWithNOLINTinMacro(const SourceManager &SM,
-                                          SourceLocation Loc, unsigned DiagID,
-                                          const ClangTidyContext &Context,
-                                          bool AllowIO) {
+static bool lineIsMarkedWithNOLINTinMacro(
+    const Diagnostic &Info, const ClangTidyContext &Context,
+    SmallVectorImpl<ClangTidyError> &SuppressionErrors, bool AllowIO) {
+  const SourceManager &SM = Info.getSourceManager();
+  SourceLocation Loc = Info.getLocation();
+  std::string CheckName = Context.getCheckName(Info.getID());
   while (true) {
-    if (LineIsMarkedWithNOLINT(SM, Loc, DiagID, Context, AllowIO))
+    if (lineIsMarkedWithNOLINT(Context, SuppressionErrors, AllowIO, SM, Loc,
+                               CheckName))
       return true;
     if (!Loc.isMacroID())
       return false;
@@ -384,12 +534,22 @@ namespace tidy {
 bool shouldSuppressDiagnostic(DiagnosticsEngine::Level DiagLevel,
                               const Diagnostic &Info, ClangTidyContext &Context,
                               bool AllowIO) {
+  SmallVector<ClangTidyError, 1> Unused;
+  bool ShouldSuppress =
+      shouldSuppressDiagnostic(DiagLevel, Info, Context, Unused, AllowIO);
+  assert(Unused.empty());
+  return ShouldSuppress;
+}
+
+bool shouldSuppressDiagnostic(
+    DiagnosticsEngine::Level DiagLevel, const Diagnostic &Info,
+    ClangTidyContext &Context,
+    SmallVectorImpl<ClangTidyError> &SuppressionErrors, bool AllowIO) {
   return Info.getLocation().isValid() &&
          DiagLevel != DiagnosticsEngine::Error &&
          DiagLevel != DiagnosticsEngine::Fatal &&
-         LineIsMarkedWithNOLINTinMacro(Info.getSourceManager(),
-                                       Info.getLocation(), Info.getID(),
-                                       Context, AllowIO);
+         lineIsMarkedWithNOLINTinMacro(Info, Context, SuppressionErrors,
+                                       AllowIO);
 }
 
 const llvm::StringMap<tooling::Replacements> *
@@ -418,7 +578,8 @@ void ClangTidyDiagnosticConsumer::HandleDiagnostic(
   if (LastErrorWasIgnored && DiagLevel == DiagnosticsEngine::Note)
     return;
 
-  if (shouldSuppressDiagnostic(DiagLevel, Info, Context)) {
+  SmallVector<ClangTidyError, 1> SuppressionErrors;
+  if (shouldSuppressDiagnostic(DiagLevel, Info, Context, SuppressionErrors)) {
     ++Context.Stats.ErrorsIgnoredNOLINT;
     // Ignored a warning, should ignore related notes as well
     LastErrorWasIgnored = true;
@@ -492,6 +653,10 @@ void ClangTidyDiagnosticConsumer::HandleDiagnostic(
 
   if (Info.hasSourceManager())
     checkFilters(Info.getLocation(), Info.getSourceManager());
+
+  Context.DiagEngine->Clear();
+  for (const auto &Error : SuppressionErrors)
+    Context.diag(Error);
 }
 
 bool ClangTidyDiagnosticConsumer::passesLineFilter(StringRef FileName,

clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h

@@ -99,6 +99,8 @@ public:
   DiagnosticBuilder diag(StringRef CheckName, StringRef Message,
                          DiagnosticIDs::Level Level = DiagnosticIDs::Warning);
 
+  DiagnosticBuilder diag(const ClangTidyError &Error);
+
   /// Report any errors to do with reading the configuration using this method.
   DiagnosticBuilder
   configurationDiag(StringRef Message,
@@ -165,7 +167,7 @@ public:
   }
 
   /// Returns build directory of the current translation unit.
-  const std::string &getCurrentBuildDirectory() {
+  const std::string &getCurrentBuildDirectory() const {
     return CurrentBuildDirectory;
   }
 
@@ -217,15 +219,24 @@ private:
 /// This is exposed so that other tools that present clang-tidy diagnostics
 /// (such as clangd) can respect the same suppression rules as clang-tidy.
 /// This does not handle suppression of notes following a suppressed diagnostic;
-/// that is left to the caller is it requires maintaining state in between calls
+/// that is left to the caller as it requires maintaining state in between calls
 /// to this function.
 /// If `AllowIO` is false, the function does not attempt to read source files
 /// from disk which are not already mapped into memory; such files are treated
 /// as not containing a suppression comment.
+/// If suppression is not possible due to improper use of "NOLINT" comments -
+/// for example, the use of a "NOLINTBEGIN" comment that is not followed by a
+/// "NOLINTEND" comment - a diagnostic regarding the improper use is returned
+/// via the output argument `SuppressionErrors`.
 bool shouldSuppressDiagnostic(DiagnosticsEngine::Level DiagLevel,
                               const Diagnostic &Info, ClangTidyContext &Context,
                               bool AllowIO = true);
 
+bool shouldSuppressDiagnostic(
+    DiagnosticsEngine::Level DiagLevel, const Diagnostic &Info,
+    ClangTidyContext &Context,
+    SmallVectorImpl<ClangTidyError> &SuppressionErrors, bool AllowIO = true);
+
 /// Gets the Fix attached to \p Diagnostic.
 /// If there isn't a Fix attached to the diagnostic and \p AnyFix is true, Check
 /// to see if exactly one note has a Fix and return it. Otherwise return

clang-tools-extra/docs/ReleaseNotes.rst

@@ -67,7 +67,8 @@ The improvements are...
 Improvements to clang-tidy
 --------------------------
 
-The improvements are...
+- Added support for `NOLINTBEGIN` ... `NOLINTEND` comments to suppress
+  Clang-Tidy warnings over multiple lines.
 
 New checks
 ^^^^^^^^^^

clang-tools-extra/docs/clang-tidy/index.rst

@@ -295,17 +295,19 @@ using explicit casts, etc.
 
 If a specific suppression mechanism is not available for a certain warning, or
 its use is not desired for some reason, :program:`clang-tidy` has a generic
-mechanism to suppress diagnostics using ``NOLINT`` or ``NOLINTNEXTLINE``
-comments.
+mechanism to suppress diagnostics using ``NOLINT``, ``NOLINTNEXTLINE``, and
+``NOLINTBEGIN`` ... ``NOLINTEND`` comments.
 
 The ``NOLINT`` comment instructs :program:`clang-tidy` to ignore warnings on the
 *same line* (it doesn't apply to a function, a block of code or any other
-language construct, it applies to the line of code it is on). If introducing the
-comment in the same line would change the formatting in undesired way, the
+language construct; it applies to the line of code it is on). If introducing the
+comment in the same line would change the formatting in an undesired way, the
 ``NOLINTNEXTLINE`` comment allows to suppress clang-tidy warnings on the *next
-line*.
+line*. The ``NOLINTBEGIN`` and ``NOLINTEND`` comments allow suppressing
+clang-tidy warnings on *multiple lines* (affecting all lines between the two
+comments).
 
-Both comments can be followed by an optional list of check names in parentheses
+All comments can be followed by an optional list of check names in parentheses
 (see below for the formal syntax).
 
 For example:
@@ -325,9 +327,16 @@ For example:
     // Silence only the specified diagnostics for the next line
     // NOLINTNEXTLINE(google-explicit-constructor, google-runtime-int)
     Foo(bool param);
+
+    // Silence only the specified checks for all lines between the BEGIN and END
+    // NOLINTBEGIN(google-explicit-constructor, google-runtime-int)
+    Foo(short param);
+    Foo(long param);
+    // NOLINTEND(google-explicit-constructor, google-runtime-int)
   };
 
-The formal syntax of ``NOLINT``/``NOLINTNEXTLINE`` is the following:
+The formal syntax of ``NOLINT``, ``NOLINTNEXTLINE``, and ``NOLINTBEGIN`` ...
+``NOLINTEND`` is the following:
 
 .. parsed-literal::
 
@@ -345,11 +354,22 @@ The formal syntax of ``NOLINT``/``NOLINTNEXTLINE`` is the following:
   lint-command:
     **NOLINT**
     **NOLINTNEXTLINE**
+    **NOLINTBEGIN**
+    **NOLINTEND**
 
-Note that whitespaces between ``NOLINT``/``NOLINTNEXTLINE`` and the opening
+Note that whitespaces between
+``NOLINT``/``NOLINTNEXTLINE``/``NOLINTBEGIN``/``NOLINTEND`` and the opening
 parenthesis are not allowed (in this case the comment will be treated just as
-``NOLINT``/``NOLINTNEXTLINE``), whereas in check names list (inside the
-parenthesis) whitespaces can be used and will be ignored.
+``NOLINT``/``NOLINTNEXTLINE``/``NOLINTBEGIN``/``NOLINTEND``), whereas in the
+check names list (inside the parentheses), whitespaces can be used and will be
+ignored.
+
+All ``NOLINTBEGIN`` comments must be paired by an equal number of ``NOLINTEND``
+comments. Moreover, a pair of comments must have matching arguments -- for
+example, ``NOLINTBEGIN(check-name)`` can be paired with
+``NOLINTEND(check-name)`` but not with ``NOLINTEND`` `(zero arguments)`.
+:program:`clang-tidy` will generate a ``clang-tidy-nolint`` error diagnostic if
+any ``NOLINTBEGIN``/``NOLINTEND`` comment violates these requirements.
 
 .. _LibTooling: https://clang.llvm.org/docs/LibTooling.html
 .. _How To Setup Tooling For LLVM: https://clang.llvm.org/docs/HowToSetupToolingForLLVM.html

clang-tools-extra/test/clang-tidy/infrastructure/Inputs/nolintbeginend/error_in_include.inc

@@ -0,0 +1 @@
+class G { G(int i); };

clang-tools-extra/test/clang-tidy/infrastructure/Inputs/nolintbeginend/nolint_in_include.inc

@@ -0,0 +1,3 @@
+// NOLINTBEGIN
+class H { H(int i); };
+// NOLINTEND

clang-tools-extra/test/clang-tidy/infrastructure/nolint.cpp

@@ -27,6 +27,9 @@ class C4 { C4(int i); }; // NOLINT(some-check, google-explicit-constructor)
 
 class C5 { C5(int i); }; // NOLINT without-brackets-skip-all, another-check
 
+class C6 { C6(int i); }; // NOLINTNEXTLINE doesn't get misconstrued as a NOLINT
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: single-argument constructors must be marked explicit
+
 void f() {
   int i;
 // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: unused variable 'i' [clang-diagnostic-unused-variable]

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-begin-at-eof.cpp

@@ -0,0 +1,12 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// CHECK: :[[@LINE+8]]:11: warning: single-argument constructors must be marked explicit
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE+5]]:4: error: unmatched 'NOLIN
+// CHECK: TBEGIN' comment without a subsequent 'NOLIN
+// CHECK: TEND' comment [clang-tidy-nolint]
+
+class A { A(int i); };
+// NOLINTBEGIN

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-begin-global-end-specific.cpp

@@ -0,0 +1,13 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// NOLINTBEGIN
+class A { A(int i); };
+// NOLINTEND(google-explicit-constructor)
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-6]]:11: warning: single-argument constructors must be marked explicit
+// CHECK: :[[@LINE-6]]:4: error: unmatched 'NOLIN
+// CHECK: TEND' comment without a previous 'NOLIN
+// CHECK: TBEGIN' comment [clang-tidy-nolint]

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-begin-specific-end-global.cpp

@@ -0,0 +1,13 @@
+// RUN: not clang-tidy %s --checks="-*,google-explicit-constructor" 2>&1 | FileCheck %s
+
+// NOLINTBEGIN(google-explicit-constructor)
+class A { A(int i); };
+// NOLINTEND
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-6]]:11: warning: single-argument constructors must be marked explicit
+// CHECK: :[[@LINE-6]]:4: error: unmatched 'NOLIN
+// CHECK: TEND' comment without a previous 'NOLIN
+// CHECK: TBEGIN' comment [clang-tidy-nolint]

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-begin-without-end.cpp

@@ -0,0 +1,12 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// NOLINTBEGIN
+class A { A(int i); };
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-6]]:4: error: unmatched 'NOLIN
+// CHECK: TBEGIN' comment without a subsequent 'NOLIN
+// CHECK: TEND' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-8]]:11: warning: single-argument constructors must be marked explicit

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-end-at-sof.cpp

@@ -0,0 +1,12 @@
+// NOLINTEND
+class A { A(int i); };
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-6]]:4: error: unmatched 'NOLIN
+// CHECK: TEND' comment without a previous 'NOLIN
+// CHECK: TBEGIN' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-8]]:11: warning: single-argument constructors must be marked explicit
+
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-end-without-begin.cpp

@@ -0,0 +1,12 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// NOLINTEND
+class A { A(int i); };
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-6]]:4: error: unmatched 'NOLIN
+// CHECK: TEND' comment without a previous 'NOLIN
+// CHECK: TBEGIN' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-8]]:11: warning: single-argument constructors must be marked explicit

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-mismatched-check-names.cpp

@@ -0,0 +1,18 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor,google-readability-casting' 2>&1 | FileCheck %s
+
+// NOLINTBEGIN(google-explicit-constructor)
+class A { A(int i); };
+auto Num = (unsigned int)(-1);
+// NOLINTEND(google-readability-casting)
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-8]]:4: error: unmatched 'NOLIN
+// CHECK: TBEGIN' comment without a subsequent 'NOLIN
+// CHECK: TEND' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-10]]:11: warning: single-argument constructors must be marked explicit
+// CHECK: :[[@LINE-10]]:12: warning: C-style casts are discouraged; use static_cast
+// CHECK: :[[@LINE-10]]:4: error: unmatched 'NOLIN
+// CHECK: TEND' comment without a previous 'NOLIN
+// CHECK: TBEGIN' comment [clang-tidy-nolint]

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-mismatched-delims.cpp

@@ -0,0 +1,14 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// NOLINTBEGIN
+// NOLINTBEGIN
+class A { A(int i); };
+// NOLINTEND
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-8]]:4: error: unmatched 'NOLIN
+// CHECK: TBEGIN' comment without a subsequent 'NOLIN
+// CHECK: TEND' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-9]]:11: warning: single-argument constructors must be marked explicit

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend-typo-in-check-name.cpp

@@ -0,0 +1,13 @@
+// RUN: not clang-tidy %s --checks='-*,google-explicit-constructor' 2>&1 | FileCheck %s
+
+// NOLINTBEGIN(google-explicit-constructor)
+class A { A(int i); };
+// NOLINTEND(google-explicit-constructo) <-- typo: missing 'r' 
+
+// Note: the expected output has been split over several lines so that clang-tidy
+//       does not see the "no lint" suppression comment and mistakenly assume it
+//       is meant for itself.
+// CHECK: :[[@LINE-7]]:4: error: unmatched 'NOLIN
+// CHECK: TBEGIN' comment without a subsequent 'NOLIN
+// CHECK: TEND' comment [clang-tidy-nolint]
+// CHECK: :[[@LINE-9]]:11: warning: single-argument constructors must be marked explicit

clang-tools-extra/test/clang-tidy/infrastructure/nolintbeginend.cpp

@@ -0,0 +1,127 @@
+// RUN: %check_clang_tidy %s google-explicit-constructor %t -- --header-filter=.* -system-headers -- -isystem %S/Inputs/nolintbeginend
+
+class A { A(int i); };
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: single-argument constructors must be marked explicit
+
+// NOLINTBEGIN
+class B1 { B1(int i); };
+// NOLINTEND
+
+// NOLINTBEGIN
+// NOLINTEND
+// NOLINTBEGIN
+class B2 { B2(int i); };
+// NOLINTEND
+
+// NOLINTBEGIN
+// NOLINTBEGIN
+class B3 { B3(int i); };
+// NOLINTEND
+// NOLINTEND
+
+// NOLINTBEGIN
+// NOLINTBEGIN
+// NOLINTEND
+class B4 { B4(int i); };
+// NOLINTEND
+
+// NOLINTBEGIN
+// NOLINTEND
+class B5 { B5(int i); };
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: single-argument constructors must be marked explicit
+
+// NOLINTBEGIN(google-explicit-constructor)
+class C1 { C1(int i); };
+// NOLINTEND(google-explicit-constructor)
+
+// NOLINTBEGIN(*)
+class C2 { C2(int i); };
+// NOLINTEND(*)
+
+// NOLINTBEGIN(some-other-check)
+class C3 { C3(int i); };
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: single-argument constructors must be marked explicit
+// NOLINTEND(some-other-check)
+
+// NOLINTBEGIN(some-other-check, google-explicit-constructor)
+class C4 { C4(int i); };
+// NOLINTEND(some-other-check, google-explicit-constructor)
+
+// NOLINTBEGIN(some-other-check, google-explicit-constructor)
+// NOLINTEND(some-other-check)
+class C5 { C5(int i); };
+// NOLINTEND(google-explicit-constructor)
+
+// NOLINTBEGIN(some-other-check, google-explicit-constructor)
+// NOLINTEND(google-explicit-constructor)
+class C6 { C6(int i); };
+// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: single-argument constructors must be marked explicit
+// NOLINTEND(some-other-check)
+
+// NOLINTBEGIN(google-explicit-constructor)
+// NOLINTBEGIN(some-other-check)
+class C7 { C7(int i); };
+// NOLINTEND(some-other-check)
+// NOLINTEND(google-explicit-constructor)
+
+// NOLINTBEGIN(google-explicit-constructor)
+// NOLINTBEGIN(some-other-check)
+class C8 { C8(int i); };
+// NOLINTEND(google-explicit-constructor)
+// NOLINTEND(some-other-check)
+
+// NOLINTBEGIN(google-explicit-constructor)
+// NOLINTBEGIN
+class C9 { C9(int i); };
+// NOLINTEND
+// NOLINTEND(google-explicit-constructor)
+
+// NOLINTBEGIN
+// NOLINTBEGIN(google-explicit-constructor)
+class C10 { C10(int i); };
+// NOLINTEND(google-explicit-constructor)
+// NOLINTEND
+
+// NOLINTBEGIN(not-closed-bracket-is-treated-as-skip-all
+class C11 { C11(int i); };
+// NOLINTEND(not-closed-bracket-is-treated-as-skip-all
+
+// NOLINTBEGIN without-brackets-skip-all, another-check
+class C12 { C12(int i); };
+// NOLINTEND without-brackets-skip-all, another-check
+
+#define MACRO(X) class X { X(int i); };
+
+MACRO(D1)
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: single-argument constructors must be marked explicit
+// CHECK-MESSAGES: :[[@LINE-4]]:28: note: expanded from macro 'MACRO
+
+// NOLINTBEGIN
+MACRO(D2)
+// NOLINTEND
+
+#define MACRO_NOARG class E { E(int i); };
+
+// NOLINTBEGIN
+MACRO_NOARG
+// NOLINTEND
+
+#include "error_in_include.inc"
+// CHECK-MESSAGES: error_in_include.inc:1:11: warning: single-argument constructors must be marked explicit
+
+#include "nolint_in_include.inc"
+
+// NOLINTBEGIN
+#define MACRO_WRAPPED_WITH_NO_LINT class I { I(int i); };
+// NOLINTEND
+
+MACRO_WRAPPED_WITH_NO_LINT
+
+#define MACRO_NO_LINT_INSIDE_MACRO \
+  /* NOLINTBEGIN */                \
+  class J { J(int i); };           \
+  /* NOLINTEND */
+
+MACRO_NO_LINT_INSIDE_MACRO
+
+// CHECK-MESSAGES: Suppressed 19 warnings (19 NOLINT).

clang-tools-extra/test/clang-tidy/infrastructure/nolintnextline.cpp

@@ -1,49 +1,51 @@
+// NOLINTNEXTLINE
 class A { A(int i); };
+
+class B { B(int i); };
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: single-argument constructors must be marked explicit
 
 // NOLINTNEXTLINE
-class B { B(int i); };
+class C { C(int i); };
 
 // NOLINTNEXTLINE(for-some-other-check)
-class C { C(int i); };
+class D { D(int i); };
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: single-argument constructors must be marked explicit
 
 // NOLINTNEXTLINE(*)
-class C1 { C1(int i); };
+class D1 { D1(int i); };
 
 // NOLINTNEXTLINE(not-closed-bracket-is-treated-as-skip-all
-class C2 { C2(int i); };
+class D2 { D2(int i); };
 
 // NOLINTNEXTLINE(google-explicit-constructor)
-class C3 { C3(int i); };
+class D3 { D3(int i); };
 
 // NOLINTNEXTLINE(some-check, google-explicit-constructor)
-class C4 { C4(int i); };
+class D4 { D4(int i); };
 
 // NOLINTNEXTLINE without-brackets-skip-all, another-check
-class C5 { C5(int i); };
-
+class D5 { D5(int i); };
 
 // NOLINTNEXTLINE
 
-class D { D(int i); };
+class E { E(int i); };
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: single-argument constructors must be marked explicit
 
 // NOLINTNEXTLINE
 //
-class E { E(int i); };
+class F { F(int i); };
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: single-argument constructors must be marked explicit
 
 #define MACRO(X) class X { X(int i); };
-MACRO(F)
+MACRO(G)
 // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: single-argument constructors must be marked explicit
 // NOLINTNEXTLINE
-MACRO(G)
+MACRO(H)
 
-#define MACRO_NOARG class H { H(int i); };
+#define MACRO_NOARG class I { I(int i); };
 // NOLINTNEXTLINE
 MACRO_NOARG
 
-// CHECK-MESSAGES: Suppressed 8 warnings (8 NOLINT)
+// CHECK-MESSAGES: Suppressed 9 warnings (9 NOLINT)
 
 // RUN: %check_clang_tidy %s google-explicit-constructor %t --