[clang-tidy] Introduce HeaderFileExtensions and ImplementationFileExtensions options

We have a number of checks designed to analyze problems
in header files only, for example:

bugprone-suspicious-include
google-build-namespaces
llvm-header-guard
misc-definitions-in-header
...

All these checks duplicate the same logic and options
to determine whether a location is placed in the main
source file or in the header. More checks are coming
up with similar requirements.

Thus, to remove duplication, let's move this option
to the top-level configuration of clang-tidy (since
it's something all checks should share).

Since the checks fetch the option via getLocalOrGlobal,
the behavior is unchanged.

Add a deprecation notice for all checks that use the
local option, prompting to update to the global option.

The functionality for parsing the option will need to
remain in the checks during the transition period.
Once the local options are fully removed, the goal
is to store the parsed options in the ClangTidyContext,
that checks can easily have access to.

Differential Revision: https://reviews.llvm.org/D141000

Author: carlosgalvezp

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

@@ -122,6 +122,9 @@ template <> struct MappingTraits<ClangTidyOptions> {
     bool Ignored = false;
     IO.mapOptional("Checks", Options.Checks);
     IO.mapOptional("WarningsAsErrors", Options.WarningsAsErrors);
+    IO.mapOptional("HeaderFileExtensions", Options.HeaderFileExtensions);
+    IO.mapOptional("ImplementationFileExtensions",
+                   Options.ImplementationFileExtensions);
     IO.mapOptional("HeaderFilterRegex", Options.HeaderFilterRegex);
     IO.mapOptional("AnalyzeTemporaryDtors", Ignored); // deprecated
     IO.mapOptional("FormatStyle", Options.FormatStyle);
@@ -142,6 +145,8 @@ ClangTidyOptions ClangTidyOptions::getDefaults() {
   ClangTidyOptions Options;
   Options.Checks = "";
   Options.WarningsAsErrors = "";
+  Options.HeaderFileExtensions = {"", "h", "hh", "hpp", "hxx"};
+  Options.ImplementationFileExtensions = {"c", "cc", "cpp", "cxx"};
   Options.HeaderFilterRegex = "";
   Options.SystemHeaders = false;
   Options.FormatStyle = "none";
@@ -178,6 +183,9 @@ ClangTidyOptions &ClangTidyOptions::mergeWith(const ClangTidyOptions &Other,
                                               unsigned Order) {
   mergeCommaSeparatedLists(Checks, Other.Checks);
   mergeCommaSeparatedLists(WarningsAsErrors, Other.WarningsAsErrors);
+  overrideValue(HeaderFileExtensions, Other.HeaderFileExtensions);
+  overrideValue(ImplementationFileExtensions,
+                Other.ImplementationFileExtensions);
   overrideValue(HeaderFilterRegex, Other.HeaderFilterRegex);
   overrideValue(SystemHeaders, Other.SystemHeaders);
   overrideValue(FormatStyle, Other.FormatStyle);

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

@@ -72,6 +72,14 @@ struct ClangTidyOptions {
   /// WarningsAsErrors filter.
   std::optional<std::string> WarningsAsErrors;
 
+  /// File extensions to consider to determine if a given diagnostic is located
+  /// in a header file.
+  std::optional<std::vector<std::string>> HeaderFileExtensions;
+
+  /// File extensions to consider to determine if a given diagnostic is located
+  /// is located in an implementation file.
+  std::optional<std::vector<std::string>> ImplementationFileExtensions;
+
   /// Output warnings from headers matching this filter. Warnings from
   /// main files will always be displayed.
   std::optional<std::string> HeaderFilterRegex;

clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp

@@ -46,12 +46,14 @@ Configuration files:
 
     $ clang-tidy -dump-config
     ---
-    Checks:              '-*,some-check'
-    WarningsAsErrors:    ''
-    HeaderFilterRegex:   ''
-    FormatStyle:         none
-    InheritParentConfig: true
-    User:                user
+    Checks:                       '-*,some-check'
+    WarningsAsErrors:             ''
+    HeaderFileExtensions:         ['', 'h','hh','hpp','hxx']
+    ImplementationFileExtensions: ['c','cc','cpp','cxx']
+    HeaderFilterRegex:            ''
+    FormatStyle:                  none
+    InheritParentConfig:          true
+    User:                         user
     CheckOptions:
       some-check.SomeOption: 'some value'
     ...
@@ -130,10 +132,10 @@ well.
                                cl::init(false), cl::cat(ClangTidyCategory));
 
 static cl::opt<bool> FixNotes("fix-notes", cl::desc(R"(
-If a warning has no fix, but a single fix can 
-be found through an associated diagnostic note, 
-apply the fix. 
-Specifying this flag will implicitly enable the 
+If a warning has no fix, but a single fix can
+be found through an associated diagnostic note,
+apply the fix.
+Specifying this flag will implicitly enable the
 '--fix' flag.
 )"),
                               cl::init(false), cl::cat(ClangTidyCategory));
@@ -458,6 +460,26 @@ static bool verifyChecks(const StringSet<> &AllChecks, StringRef CheckGlob,
   return AnyInvalid;
 }
 
+static bool verifyFileExtensions(
+    const std::vector<std::string> &HeaderFileExtensions,
+    const std::vector<std::string> &ImplementationFileExtensions,
+    StringRef Source) {
+  bool AnyInvalid = false;
+  for (const auto &HeaderExtension : HeaderFileExtensions) {
+    for (const auto &ImplementationExtension : ImplementationFileExtensions) {
+      if (HeaderExtension == ImplementationExtension) {
+        AnyInvalid = true;
+        auto &Output = llvm::WithColor::warning(llvm::errs(), Source)
+                       << "HeaderFileExtension '" << HeaderExtension << '\''
+                       << " is the same as ImplementationFileExtension '"
+                       << ImplementationExtension << '\'';
+        Output << VerifyConfigWarningEnd;
+      }
+    }
+  }
+  return AnyInvalid;
+}
+
 int clangTidyMain(int argc, const char **argv) {
   llvm::InitLLVM X(argc, argv);
 
@@ -561,6 +583,11 @@ int clangTidyMain(int argc, const char **argv) {
       if (Opts.Checks)
         AnyInvalid |= verifyChecks(Valid.Names, *Opts.Checks, Source);
 
+      if (Opts.HeaderFileExtensions && Opts.ImplementationFileExtensions)
+        AnyInvalid |=
+            verifyFileExtensions(*Opts.HeaderFileExtensions,
+                                 *Opts.ImplementationFileExtensions, Source);
+
       for (auto Key : Opts.CheckOptions.keys()) {
         if (Valid.Options.contains(Key))
           continue;

clang-tools-extra/docs/ReleaseNotes.rst

@@ -106,6 +106,10 @@ Improvements to clang-tidy
   which is no longer in use. The option will be fully removed in
   :program:`clang-tidy` version 18.
 
+- New global configuration file options `HeaderFileExtensions` and
+  `ImplementationFileExtensions`, replacing the check-local options of the
+  same name.
+
 New checks
 ^^^^^^^^^^
 
@@ -157,26 +161,61 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/assignment-in-if-condition>` check when there
   was an assignement in a lambda found in the condition of an ``if``.
 
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`bugprone-dynamic-static-initializers
+  <clang-tidy/checks/bugprone/dynamic-static-initializers>` check.
+  Global options of the same name should be used instead.
+
 - Improved :doc:`bugprone-signal-handler
   <clang-tidy/checks/bugprone/signal-handler>` check. Partial
   support for C++14 signal handler rules was added. Bug report generation was
   improved.
 
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`bugprone-suspicious-include
+  <clang-tidy/checks/bugprone/suspicious-include>` check.
+  Global options of the same name should be used instead.
+
 - Fixed a false positive in :doc:`cppcoreguidelines-pro-type-member-init
   <clang-tidy/checks/cppcoreguidelines/pro-type-member-init>` when warnings
   would be emitted for uninitialized members of an anonymous union despite
   there being an initializer for one of the other members.
 
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`google-build-namespaces
+  <clang-tidy/checks/google/build-namespaces>` check.
+  Global options of the same name should be used instead.
+
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`google-global-names-in-headers
+  <clang-tidy/checks/google/global-names-in-headers>` check.
+  Global options of the same name should be used instead.
+
 - Fixed false positives in :doc:`google-objc-avoid-throwing-exception
   <clang-tidy/checks/google/objc-avoid-throwing-exception>` check for exceptions
   thrown by code emitted from macros in system headers.
 
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`llvm-header-guard
+  <clang-tidy/checks/llvm/header-guard>` check.
+  Global options of the same name should be used instead.
+
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`misc-definitions-in-headers
+  <clang-tidy/checks/misc/definitions-in-headers>` check.
+  Global options of the same name should be used instead.
+
 - Improved :doc:`misc-redundant-expression <clang-tidy/checks/misc/redundant-expression>`
   check.
 
   The check now skips concept definitions since redundant expressions still make sense
   inside them.
 
+- Deprecated check-local options `HeaderFileExtensions` and `ImplementationFileExtensions`
+  in :doc:`misc-unused-using-decls
+  <clang-tidy/checks/misc/misc-unused-using-decls>` check.
+  Global options of the same name should be used instead.
+
 - Improved :doc:`modernize-loop-convert <clang-tidy/checks/modernize/loop-convert>`
   to check for container functions ``begin``/``end`` etc on base classes of the container
   type, instead of only as direct members of the container type itself.

clang-tools-extra/docs/clang-tidy/checks/bugprone/suspicious-include.rst

@@ -19,6 +19,10 @@ Options
 -------
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    Default value: ``";h;hh;hpp;hxx"``
    A semicolon-separated list of filename extensions of header files (the
    filename extensions should not contain a "." prefix). For extension-less
@@ -27,6 +31,10 @@ Options
 
 .. option:: ImplementationFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`.
+   version 18. Please use the global configuration option
+   `ImplementationFileExtensions`.
+
    Default value: ``"c;cc;cpp;cxx"``
    Likewise, a semicolon-separated list of filename extensions of
    implementation files.

clang-tools-extra/docs/clang-tidy/checks/google/build-namespaces.rst

@@ -17,6 +17,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A comma-separated list of filename extensions of header files (the filename
    extensions should not include "." prefix). Default is "h,hh,hpp,hxx".
    For header files without an extension, use an empty string (if there are no

clang-tools-extra/docs/clang-tidy/checks/google/global-names-in-headers.rst

@@ -14,6 +14,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A comma-separated list of filename extensions of header files (the filename
    extensions should not contain "." prefix). Default is "h".
    For header files without an extension, use an empty string (if there are no

clang-tools-extra/docs/clang-tidy/checks/llvm/header-guard.rst

@@ -10,6 +10,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A comma-separated list of filename extensions of header files (the filename
    extensions should not include "." prefix). Default is "h,hh,hpp,hxx".
    For header files without an extension, use an empty string (if there are no

clang-tools-extra/docs/clang-tidy/checks/misc/definitions-in-headers.rst

@@ -92,6 +92,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A comma-separated list of filename extensions of header files (the filename
    extensions should not include "." prefix). Default is "h,hh,hpp,hxx".
    For header files without an extension, use an empty string (if there are no
@@ -100,5 +104,9 @@ Options
 
 .. option:: UseHeaderFileExtension
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. The check will unconditionally use the global option
+   `HeaderFileExtensions`.
+
    When `true`, the check will use the file extension to distinguish header
    files. Default is `true`.

clang-tools-extra/docs/clang-tidy/checks/misc/unused-using-decls.rst

@@ -22,6 +22,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A semicolon-separated list of filename extensions of header files (the filename
    extensions should not include "." prefix). Default is "h,hh,hpp,hxx".
    For extension-less header files, use an empty string or leave an

clang-tools-extra/docs/clang-tidy/checks/misc/use-anonymous-namespace.rst

@@ -38,6 +38,10 @@ Options
 
 .. option:: HeaderFileExtensions
 
+   Note: this option is deprecated, it will be removed in :program:`clang-tidy`
+   version 18. Please use the global configuration option
+   `HeaderFileExtensions`.
+
    A semicolon-separated list of filename extensions of header files (the filename
    extensions should not include "." prefix). Default is ";h;hh;hpp;hxx".
    For extension-less header files, using an empty string or leaving an

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

@@ -139,7 +139,7 @@ An overview of all the command-line options:
                                      When the value is empty, clang-tidy will
                                      attempt to find a file named .clang-tidy for
                                      each source file in its parent directories.
-    --config-file=<string>         - 
+    --config-file=<string>         -
                                     Specify the path of .clang-tidy or custom config file:
                                       e.g. --config-file=/some/path/myTidyConfigFile
                                     This option internally works exactly the same way as
@@ -237,7 +237,7 @@ An overview of all the command-line options:
                                      format to stderr. When this option is passed,
                                      these per-TU profiles are instead stored as JSON.
     --system-headers               - Display the errors from system headers.
-    --use-color                    - 
+    --use-color                    -
                                     Use colors in diagnostics. If not set, colors
                                     will be used if the terminal connected to
                                     standard output supports colors.
@@ -287,12 +287,14 @@ An overview of all the command-line options:
 
       $ clang-tidy -dump-config
       ---
-      Checks:              '-*,some-check'
-      WarningsAsErrors:    ''
-      HeaderFilterRegex:   ''
-      FormatStyle:         none
-      InheritParentConfig: true
-      User:                user
+      Checks:                       '-*,some-check'
+      WarningsAsErrors:             ''
+      HeaderFileExtensions:         ['', 'h','hh','hpp','hxx']
+      ImplementationFileExtensions: ['c','cc','cpp','cxx']
+      HeaderFilterRegex:            ''
+      FormatStyle:                  none
+      InheritParentConfig:          true
+      User:                         user
       CheckOptions:
         some-check.SomeOption: 'some value'
       ...

clang-tools-extra/test/clang-tidy/infrastructure/verify-config.cpp

@@ -3,6 +3,8 @@
 
 // RUN: not clang-tidy -verify-config \
 // RUN: --checks='-*,bad*glob,llvm*,llvm-includeorder,my-made-up-check' --config='{Checks: "readability-else-after-ret", \
+// RUN: HeaderFileExtensions: ["h", "hh", "hpp"], \
+// RUN: ImplementationFileExtensions: ["c", "cc", "hpp"], \
 // RUN: CheckOptions: [{key: "IgnoreMacros", value: "true"}, \
 // RUN:                {key: "StriceMode", value: "true"}, \
 // RUN:                {key: modernize-lop-convert.UseCxx20ReverseRanges, value: true} \
@@ -12,6 +14,7 @@
 // CHECK-VERIFY-DAG: command-line option '-config': warning: unknown check 'readability-else-after-ret'; did you mean 'readability-else-after-return' [-verify-config]
 // CHECK-VERIFY-DAG: command-line option '-config': warning: unknown check option 'modernize-lop-convert.UseCxx20ReverseRanges'; did you mean 'modernize-loop-convert.UseCxx20ReverseRanges' [-verify-config]
 // CHECK-VERIFY-DAG: command-line option '-config': warning: unknown check option 'StriceMode'; did you mean 'StrictMode' [-verify-config]
+// CHECK-VERIFY-DAG: command-line option '-config': warning: HeaderFileExtension 'hpp' is the same as ImplementationFileExtension 'hpp' [-verify-config]
 // CHECK-VERIFY: command-line option '-checks': warning: check glob 'bad*glob' doesn't match any known check [-verify-config]
 // CHECK-VERIFY: command-line option '-checks': warning: unknown check 'llvm-includeorder'; did you mean 'llvm-include-order' [-verify-config]
 // CHECK-VERIFY: command-line option '-checks': warning: unknown check 'my-made-up-check' [-verify-config]