[clang-tidy] ignore consteval function in ExceptionAnalyzer

[HerrCai0907]

ExceptionAnalyzer can ignore consteval function even if it will throw exception. consteval function must produce compile-time constant. But throw statement cannot appear in constant evaluation.
Fixed: #104457.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

@llvm/pr-subscribers-clang-tools-extra

Author: Congcong Cai (HerrCai0907)

Changes

ExceptionAnalyzer can ignore consteval function even if it will throw exception. consteval function must produce compile-time constant. But throw statement cannot appear in constant evaluation.
Fixed: #104457.

---

Full diff: https://github.com/llvm/llvm-project/pull/116643.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp (+5)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+4)
• (added) clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape-consteval.cpp (+14)

diff --git a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
index 9bfb7e2677533a..740c7852439219 100644
--- a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
@@ -320,6 +320,11 @@ bool isQualificationConvertiblePointer(QualType From, QualType To,
 } // namespace
 
 static bool canThrow(const FunctionDecl *Func) {
+  // consteval specifies every call to the function must produce a compile-time
+  // constant. compile-time constant cannot be evaluate a throw expression.
+  if (Func->isConsteval())
+    return false;
+
   const auto *FunProto = Func->getType()->getAs<FunctionProtoType>();
   if (!FunProto)
     return true;
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index f967dfabd1c940..70f62f2dc8c393 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -162,6 +162,10 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/dangling-handle>` check to treat `std::span` as a
   handle class.
 
+- Improved :doc:`bugprone-exception-escape
+  <clang-tidy/checks/bugprone/exception-escape>` by fixing false positives
+  when consteval function with throw statements.
+
 - Improved :doc:`bugprone-forwarding-reference-overload
   <clang-tidy/checks/bugprone/forwarding-reference-overload>` check by fixing
   a crash when determining if an ``enable_if[_t]`` was found.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape-consteval.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape-consteval.cpp
new file mode 100644
index 00000000000000..6e4298bba8bf1f
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/exception-escape-consteval.cpp
@@ -0,0 +1,14 @@
+// RUN: %check_clang_tidy -std=c++20 %s bugprone-exception-escape %t -- \
+// RUN:     -- -fexceptions -Wno-everything
+
+namespace GH104457 {
+
+consteval int consteval_fn(int a) {
+  if (a == 0)
+    throw 1;
+  return a;
+}
+
+int test() noexcept { return consteval_fn(1); }
+
+} // namespace GH104457

[5chmidti]

LGTM minus comment nits

[5chmidti]

when encountering a

[5chmidti]

// consteval specifies that every call to the function must produce a compile-time
// constant, which cannot evaluate a throw expression without producing a compilation error.