[clang-tools-extra] [clang-tidy] Fix crash in modernize-use-constraints (PR #92019)

[Piotr Zegar via cfe-commits]

https://github.com/PiotrZSL updated https://github.com/llvm/llvm-project/pull/92019

>From 5f0302b0d1c34d13b566aa6f992568005a47fac0 Mon Sep 17 00:00:00 2001
From: Piotr Zegar <me at piotrzegar.pl>
Date: Mon, 13 May 2024 19:47:44 +0000
Subject: [PATCH 1/2] [clang-tidy] Fix crash in modernize-use-constraints

Improved modernize-use-constraints check by fixing a crash that
occurred in some scenarios and excluded system headers from analysis.

Problem were with DependentNameTypeLoc having null type
location as getQualifierLoc().getTypeLoc().

Fixes #91872
---
 .../modernize/UseConstraintsCheck.cpp         |  4 +++
 clang-tools-extra/docs/ReleaseNotes.rst       |  4 +++
 .../checks/modernize/use-constraints.rst      |  4 +++
 .../checkers/modernize/use-constraints.cpp    | 32 +++++++++++++++++++
 4 files changed, 44 insertions(+)

diff --git a/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp
index 6d7d1d6b87c60..d9fab64050adb 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp
@@ -41,6 +41,8 @@ AST_MATCHER(FunctionDecl, hasOtherDeclarations) {
 void UseConstraintsCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
       functionTemplateDecl(
+          // Skip external libraries included as system headers
+          unless(isExpansionInSystemHeader()),
           has(functionDecl(unless(hasOtherDeclarations()), isDefinition(),
                            hasReturnTypeLoc(typeLoc().bind("return")))
                   .bind("function")))
@@ -57,6 +59,8 @@ matchEnableIfSpecializationImplTypename(TypeLoc TheType) {
       return std::nullopt;
     }
     TheType = Dep.getQualifierLoc().getTypeLoc();
+    if (TheType.isNull())
+      return std::nullopt;
   }
 
   if (const auto SpecializationLoc =
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index fc976ce3a33d5..91b24f654112f 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -306,6 +306,10 @@ Changes in existing checks
   don't remove parentheses used in ``sizeof`` calls when they have array index
   accesses as arguments.
 
+- Improved :doc:`modernize-use-constraints
+  <clang-tidy/checks/modernize/use-constraints>` check by fixing a crash that
+  occurred in some scenarios and excluded system headers from analysis.
+
 - Improved :doc:`modernize-use-nullptr
   <clang-tidy/checks/modernize/use-nullptr>` check to include support for C23,
   which also has introduced the ``nullptr`` keyword.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-constraints.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-constraints.rst
index be62dd5823d55..a8b31b80e580b 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-constraints.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-constraints.rst
@@ -68,3 +68,7 @@ The tool will replace the above code with,
   // The tool will not emit a diagnostic or attempt to replace the code.
   template <typename T, std::enable_if_t<T::some_trait, int> = 0>
   struct my_class {};
+
+.. note::
+
+  System headers are not analyzed by this check.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-constraints.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-constraints.cpp
index 3ec44be8a1c8c..3bcd5cd74024e 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-constraints.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-constraints.cpp
@@ -724,3 +724,35 @@ void not_last_param() {
 }
 
 } // namespace enable_if_trailing_type_parameter
+
+
+// Issue fixes:
+
+namespace PR91872 {
+
+enum expression_template_option { value1, value2 };
+
+template <typename T> struct number_category {
+  static const int value = 0;
+};
+
+constexpr int number_kind_complex = 1;
+
+template <typename T, expression_template_option ExpressionTemplates>
+struct number {
+  using type = T;
+};
+
+template <typename T> struct component_type {
+  using type = T;
+};
+
+template <class T, expression_template_option ExpressionTemplates>
+inline typename std::enable_if<
+    number_category<T>::value == number_kind_complex,
+    component_type<number<T, ExpressionTemplates>>>::type::type
+abs(const number<T, ExpressionTemplates> &v) {
+  return {};
+}
+
+}

>From fd5fa3e94ade53bfa78850879f3dfa287697277b Mon Sep 17 00:00:00 2001
From: Piotr Zegar <me at piotrzegar.pl>
Date: Tue, 14 May 2024 19:18:06 +0200
Subject: [PATCH 2/2] Update clang-tools-extra/docs/ReleaseNotes.rst

Co-authored-by: Congcong Cai <congcongcai0907 at 163.com>
---
 clang-tools-extra/docs/ReleaseNotes.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 91b24f654112f..e30b7bc3cd22d 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -308,7 +308,7 @@ Changes in existing checks
 
 - Improved :doc:`modernize-use-constraints
   <clang-tidy/checks/modernize/use-constraints>` check by fixing a crash that
-  occurred in some scenarios and excluded system headers from analysis.
+  occurred in some scenarios and excluding system headers from analysis.
 
 - Improved :doc:`modernize-use-nullptr
   <clang-tidy/checks/modernize/use-nullptr>` check to include support for C23,