https://github.com/tkoeppe updated
https://github.com/llvm/llvm-project/pull/109169
From 07df4ed66b36fab2da9a2ae83ab85d8fcb39aa3f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20K=C3=B6ppe?= <tkoe...@google.com>
Date: Wed, 18 Sep 2024 17:04:44 +0000
Subject: [PATCH] [clang-tidy] Make modernize-use-nullptr matcher also match
"NULL", but not "0", when it appears on a substituted type of a template
specialization.
Previously, any matches on a substituted type were excluded, but this meant
that a situation like the following is not diagnosed:
```c++
template <typename T>
struct X {
T val;
X() { val = NULL; } // should diagnose
};
```
When the user says `NULL`, we expect that the destination type is always meant
to be a pointer type, so this should be converted to `nullptr`. By contrast, we
do not propose changing a literal `0` in that case, which appears as
initializers of both pointer and integer specializations in reasonable real
code. (If `NULL` is used erroneously in such a situation, it should be changed
to `0` or `{}`.)
---
.../clang-tidy/modernize/UseNullptrCheck.cpp | 12 ++++++++-
clang-tools-extra/docs/ReleaseNotes.rst | 4 +++
.../checkers/modernize/use-nullptr.cpp | 25 +++++++++++++++++++
3 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
b/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
index 6a003a347badac..108717e151b577 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
@@ -35,10 +35,20 @@ AST_MATCHER(Type, sugaredNullptrType) {
/// to null within.
/// Finding sequences of explicit casts is necessary so that an entire sequence
/// can be replaced instead of just the inner-most implicit cast.
+///
+/// TODO/NOTE: The second "anyOf" below discards matches on a substituted type,
+/// since we don't know if that would _always_ be a pointer type for all other
+/// specializations, unless the expression was "__null", in which case we
assume
+/// that all specializations are expected to be for pointer types. Ideally this
+/// would check for the "NULL" macro instead, but that'd be harder to express.
+/// In practice, "NULL" is often defined as "__null", and this is a useful
+/// condition.
StatementMatcher makeCastSequenceMatcher(llvm::ArrayRef<StringRef> NameList) {
auto ImplicitCastToNull = implicitCastExpr(
anyOf(hasCastKind(CK_NullToPointer),
hasCastKind(CK_NullToMemberPointer)),
-
unless(hasImplicitDestinationType(qualType(substTemplateTypeParmType()))),
+ anyOf(hasSourceExpression(gnuNullExpr()),
+ unless(hasImplicitDestinationType(
+ qualType(substTemplateTypeParmType())))),
unless(hasSourceExpression(hasType(sugaredNullptrType()))),
unless(hasImplicitDestinationType(
qualType(matchers::matchesAnyListedTypeName(NameList)))));
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst
b/clang-tools-extra/docs/ReleaseNotes.rst
index d032cef6b76164..b2bb7549f840cc 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -157,6 +157,10 @@ Changes in existing checks
a false positive when only an implicit conversion happened inside an
initializer list.
+- Improved :doc:`modernize-use-nullptr
+ <clang-tidy/checks/modernize/use-nullptr>` check to also recognize
+ ``NULL``/``__null`` (but not ``0``) when used with a templated type.
+
- Improved :doc:`modernize-use-std-print
<clang-tidy/checks/modernize/use-std-print>` check to support replacing
member function calls too.
diff --git
a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-nullptr.cpp
b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-nullptr.cpp
index 7bc0925136aa86..2c36349da896cf 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-nullptr.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-nullptr.cpp
@@ -84,6 +84,31 @@ void test_macro_expansion4() {
#undef MY_NULL
}
+template <typename T> struct pear {
+ // If you say __null (or NULL), we assume that T will always be a pointer
+ // type, so we suggest replacing it with nullptr. (We only check __null here,
+ // because in this test NULL is defined as 0, but real library
implementations
+ // it is often defined as __null and the check will catch it.)
+ void f() { x = __null; }
+ // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: use nullptr
[modernize-use-nullptr]
+ // CHECK-FIXES: x = nullptr;
+
+ // But if you say 0, we allow the possibility that T can be used with
integral
+ // and pointer types, and "0" is an acceptable initializer (even if "{}"
might
+ // be even better).
+ void g() { y = 0; }
+ // CHECK-MESSAGES-NOT: :[[@LINE-1]] warning: use nullptr
+
+ T x;
+ T y;
+};
+void test_templated() {
+ pear<int*> p;
+ p.f();
+ p.g();
+ dummy(p.x);
+}
+
#define IS_EQ(x, y) if (x != y) return;
void test_macro_args() {
int i = 0;
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