[clang-tidy] Support functional cast in bugprone-dangling-handle

[PiotrZSL]

Add support for constructor conversion based functional
cast. Allows to detect issues like:
const std::string_view test1 = std::string(a);

[llvmbot]

@llvm/pr-subscribers-clang-tidy

Author: Piotr Zegar (PiotrZSL)

Changes

Add support for constructor conversion based functional
cast. Allows to detect issues like:
const std::string_view test1 = std::string(a);

---

Full diff: https://github.com/llvm/llvm-project/pull/69067.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp (+8-3)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
• (modified) clang-tools-extra/test/clang-tidy/checkers/bugprone/dangling-handle.cpp (+8)

diff --git a/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
index 9ded699ba78e66b..ffaa1edc83e7299 100644
--- a/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
@@ -33,14 +33,19 @@ handleFrom(const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle,
 
 ast_matchers::internal::Matcher<Stmt> handleFromTemporaryValue(
     const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle) {
+
+  const auto TemporaryExpr =
+      anyOf(cxxBindTemporaryExpr(),
+            cxxFunctionalCastExpr(hasCastKind(CK_ConstructorConversion),
+                                  hasSourceExpression(cxxBindTemporaryExpr())));
   // If a ternary operator returns a temporary value, then both branches hold a
   // temporary value. If one of them is not a temporary then it must be copied
   // into one to satisfy the type of the operator.
   const auto TemporaryTernary = conditionalOperator(
-      hasTrueExpression(ignoringParenImpCasts(cxxBindTemporaryExpr())),
-      hasFalseExpression(ignoringParenImpCasts(cxxBindTemporaryExpr())));
+      hasTrueExpression(ignoringParenImpCasts(TemporaryExpr)),
+      hasFalseExpression(ignoringParenImpCasts(TemporaryExpr)));
 
-  return handleFrom(IsAHandle, anyOf(cxxBindTemporaryExpr(), TemporaryTernary));
+  return handleFrom(IsAHandle, anyOf(TemporaryExpr, TemporaryTernary));
 }
 
 ast_matchers::internal::Matcher<RecordDecl> isASequence() {
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 03e5dc6f164af2a..35d02f7c42f82fd 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -190,6 +190,11 @@ New check aliases
 Changes in existing checks
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+- Improved :doc:`bugprone-dangling-handle
+  <clang-tidy/checks/bugprone/dangling-handle>` check to support functional
+  casting during type conversions at variable initialization, now with improved
+  compatibility for C++17 and later versions.
+
 - Improved :doc:`bugprone-lambda-function-name
   <clang-tidy/checks/bugprone/lambda-function-name>` check by adding option
   `IgnoreMacros` to ignore warnings in macros.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/dangling-handle.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/dangling-handle.cpp
index 23cda5321764383..96c812617038a37 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/dangling-handle.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/dangling-handle.cpp
@@ -108,6 +108,14 @@ void Positives() {
   std::string_view view4(ReturnsAString());
   // CHECK-MESSAGES-CXX14: [[@LINE-1]]:20: warning: std::basic_string_view outlives
   // CHECK-MESSAGES-CXX17: [[@LINE-2]]:26: warning: std::basic_string_view outlives
+
+  std::string_view view5 = std::string("test");
+  // CHECK-MESSAGES-CXX14: [[@LINE-1]]:20: warning: std::basic_string_view outlives its value [bugprone-dangling-handle]
+  // CHECK-MESSAGES-CXX17: [[@LINE-2]]:28: warning: std::basic_string_view outlives its value [bugprone-dangling-handle]
+
+  std::string_view view6 = std::string{"test"};
+  // CHECK-MESSAGES-CXX14: [[@LINE-1]]:20: warning: std::basic_string_view outlives its value [bugprone-dangling-handle]
+  // CHECK-MESSAGES-CXX17: [[@LINE-2]]:28: warning: std::basic_string_view outlives its value [bugprone-dangling-handle]
 }
 
 void OtherTypes() {