[clang-tools-extra] [clang-tidy][NFC] Update contribution guide for test language standards (PR #184769)

[via cfe-commits]

https://github.com/zeyi2 created https://github.com/llvm/llvm-project/pull/184769

None

>From 46b368037f66f1225f169be79ee6855c0f930a59 Mon Sep 17 00:00:00 2001
From: mtx <mitchell.xu2 at gmail.com>
Date: Thu, 5 Mar 2026 14:43:41 +0800
Subject: [PATCH 1/2] [clang-tidy] Fix option serialization in
 misc-throw-by-value-catch-by-reference

---
 .../ThrowByValueCatchByReferenceCheck.cpp     |  4 +-
 clang-tools-extra/docs/ReleaseNotes.rst       |  9 ++++
 ...ow-by-value-catch-by-reference-options.cpp | 50 +++++++++++++++++++
 3 files changed, 61 insertions(+), 2 deletions(-)
 create mode 100644 clang-tools-extra/test/clang-tidy/checkers/misc/throw-by-value-catch-by-reference-options.cpp

diff --git a/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp b/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
index db3a69029c069..fe4b050dd1edf 100644
--- a/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
@@ -31,8 +31,8 @@ void ThrowByValueCatchByReferenceCheck::registerMatchers(MatchFinder *Finder) {
 
 void ThrowByValueCatchByReferenceCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
-  Options.store(Opts, "CheckThrowTemporaries", true);
-  Options.store(Opts, "WarnOnLargeObjects", WarnOnLargeObject);
+  Options.store(Opts, "CheckThrowTemporaries", CheckAnonymousTemporaries);
+  Options.store(Opts, "WarnOnLargeObject", WarnOnLargeObject);
   Options.store(Opts, "MaxSize", MaxSizeOptions);
 }
 
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index cf8dd0dba9f12..1f95a22190d26 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -208,6 +208,15 @@ Changes in existing checks
   - Fixed false positive where an array of pointers to ``const`` was
     incorrectly diagnosed as allowing the pointee to be made ``const``.
 
+- Improved :doc:`misc-throw-by-value-catch-by-reference
+  <clang-tidy/checks/misc/throw-by-value-catch-by-reference>` check:
+
+  - Fixed the `WarnOnLargeObject` option to use the correct name when
+    storing the configuration.
+
+  - Fixed the `CheckThrowTemporaries` option to correctly reflect its
+    configured value in exported settings.
+
 - Improved :doc:`modernize-pass-by-value
   <clang-tidy/checks/modernize/pass-by-value>` check by adding `IgnoreMacros`
   option to suppress warnings in macros.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/throw-by-value-catch-by-reference-options.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/throw-by-value-catch-by-reference-options.cpp
new file mode 100644
index 0000000000000..f06241447de4b
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/throw-by-value-catch-by-reference-options.cpp
@@ -0,0 +1,50 @@
+// RUN: %check_clang_tidy %s misc-throw-by-value-catch-by-reference %t -- \
+// RUN:   -config="{CheckOptions: { \
+// RUN:     misc-throw-by-value-catch-by-reference.WarnOnLargeObject: true, \
+// RUN:     misc-throw-by-value-catch-by-reference.MaxSize: 200, \
+// RUN:     misc-throw-by-value-catch-by-reference.CheckThrowTemporaries: false \
+// RUN:   }}" -- -fcxx-exceptions
+
+struct LargeTrivial {
+  char data[100];
+};
+
+struct SmallTrivial {
+  char data[10];
+};
+
+struct NonTrivial {
+  NonTrivial() {}
+  NonTrivial(const NonTrivial &) {}
+  char data[100];
+};
+
+void testLargeTrivial() {
+  try {
+    throw LargeTrivial();
+  } catch (LargeTrivial e) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: catch handler catches by value; should catch by reference instead [misc-throw-by-value-catch-by-reference]
+  }
+}
+
+void testSmallTrivial() {
+  try {
+    throw SmallTrivial();
+  } catch (SmallTrivial e) {
+    // Should not warn (80 < 200)
+  }
+}
+
+void testNonTrivial() {
+  try {
+    throw NonTrivial();
+  } catch (NonTrivial e) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: catch handler catches by value; should catch by reference instead [misc-throw-by-value-catch-by-reference]
+  }
+}
+
+void testCheckThrowTemporaries() {
+  LargeTrivial lvalue;
+  throw lvalue;
+  // Should not warn when CheckThrowTemporaries is false
+}

>From 3ba36a8afc41d748ecc6215d4d6c876455f37781 Mon Sep 17 00:00:00 2001
From: mtx <mitchell.xu2 at gmail.com>
Date: Thu, 5 Mar 2026 18:52:38 +0800
Subject: [PATCH 2/2] [clang-tidy][NFC] Update contribution guide for test
 language standards

---
 .../docs/clang-tidy/Contributing.rst          | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/clang-tools-extra/docs/clang-tidy/Contributing.rst b/clang-tools-extra/docs/clang-tidy/Contributing.rst
index 72444480ece0e..d0cc43f9bbad9 100644
--- a/clang-tools-extra/docs/clang-tidy/Contributing.rst
+++ b/clang-tools-extra/docs/clang-tidy/Contributing.rst
@@ -662,6 +662,28 @@ Here's an example:
    // CHECK-FIXES-USING-B-NOT: using a::B;$
    // CHECK-FIXES-NOT: using a::C;$
 
+Specifying the Language Standard
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ``-std`` flag controls which C or C++ standard(s) the test is compiled
+under. It accepts a comma-separated list of standards and supports an
+``-or-later`` suffix:
+
+- ``-std=c++17``: runs the test **only** with C++17.
+- ``-std=c++17-or-later``: runs the test once for each standard from C++17
+  onwards (currently C++17, C++20, C++23, and C++26), in separate invocations.
+  Use this when a check should work correctly on all modern standards.
+- ``-std=c++14,c++17``: runs the test once with C++14 and once with C++17.
+
+When no ``-std`` is given, ``check_clang_tidy.py`` defaults to
+``c++11-or-later`` for C++ files and ``c99-or-later`` for C files. The check
+skeleton generated by ``add_new_check.py`` uses the ``-or-later`` form by
+default. Prefer ``-std=<minimum>-or-later`` unless the test expects
+behavior that only applies to a specific standard version.
+
+Common Pitfalls and Edge Cases
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 There are many dark corners in the C++ language, and it may be difficult to
 make your check work perfectly in all cases, especially if it issues fix-it
 hints. The most frequent pitfalls are macros and templates: