[clang-tidy] Fix cppcoreguidelines-prefer-member-initializer false positive for inherited members
#153941
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@llvm/pr-subscribers-clang-tidy Author: None (v1nh1shungry) Changesstruct Base {
int m;
};
template <class T>
struct Derived : Base {
Derived() { m = 0; }
};would previously generate the following output: This patch fixes this false positive. Note that before this patch the checker won't give false positive for struct Derived : Base {
Derived() { m = 0; }
};and the constructor's AST is so Full diff: https://github.com/llvm/llvm-project/pull/153941.diff 3 Files Affected:
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
index 593a4f85d1309..79cd4bbcc9a60 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -191,6 +191,9 @@ void PreferMemberInitializerCheck::check(
if (!AssignmentToMember)
continue;
const FieldDecl *Field = AssignmentToMember->Field;
+ // Skip if the field is inherited from a base class.
+ if (Field->getParent() != Class)
+ continue;
const Expr *InitValue = AssignmentToMember->Init;
updateAssignmentLevel(Field, InitValue, Ctor, AssignedFields);
if (!canAdvanceAssignment(AssignedFields[Field]))
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1553f461634d0..0d5dbd85df6a4 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -163,6 +163,10 @@ Changes in existing checks
an additional matcher that generalizes the copy-and-swap idiom pattern
detection.
+- Improved :doc:`cppcoreguidelines-prefer-member-initializer
+ <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check by
+ no longer giving false positives for inherited members.
+
- Improved :doc:`misc-header-include-cycle
<clang-tidy/checks/misc/header-include-cycle>` check performance.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
index 7d6164946fc3d..faff4882142f1 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
@@ -650,3 +650,20 @@ struct InitFromBindingDecl {
}
};
} // namespace GH82970
+
+namespace inherited_members {
+
+struct A {
+ int m;
+};
+
+struct B : A {
+ B() { m = 0; }
+};
+
+template <class T>
+struct C : A {
+ C() { m = 0; }
+};
+
+} // namespace inherited_members
|
|
@llvm/pr-subscribers-clang-tools-extra Author: None (v1nh1shungry) Changesstruct Base {
int m;
};
template <class T>
struct Derived : Base {
Derived() { m = 0; }
};would previously generate the following output: This patch fixes this false positive. Note that before this patch the checker won't give false positive for struct Derived : Base {
Derived() { m = 0; }
};and the constructor's AST is so Full diff: https://github.com/llvm/llvm-project/pull/153941.diff 3 Files Affected:
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
index 593a4f85d1309..79cd4bbcc9a60 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -191,6 +191,9 @@ void PreferMemberInitializerCheck::check(
if (!AssignmentToMember)
continue;
const FieldDecl *Field = AssignmentToMember->Field;
+ // Skip if the field is inherited from a base class.
+ if (Field->getParent() != Class)
+ continue;
const Expr *InitValue = AssignmentToMember->Init;
updateAssignmentLevel(Field, InitValue, Ctor, AssignedFields);
if (!canAdvanceAssignment(AssignedFields[Field]))
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1553f461634d0..0d5dbd85df6a4 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -163,6 +163,10 @@ Changes in existing checks
an additional matcher that generalizes the copy-and-swap idiom pattern
detection.
+- Improved :doc:`cppcoreguidelines-prefer-member-initializer
+ <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check by
+ no longer giving false positives for inherited members.
+
- Improved :doc:`misc-header-include-cycle
<clang-tidy/checks/misc/header-include-cycle>` check performance.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
index 7d6164946fc3d..faff4882142f1 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
@@ -650,3 +650,20 @@ struct InitFromBindingDecl {
}
};
} // namespace GH82970
+
+namespace inherited_members {
+
+struct A {
+ int m;
+};
+
+struct B : A {
+ B() { m = 0; }
+};
+
+template <class T>
+struct C : A {
+ C() { m = 0; }
+};
+
+} // namespace inherited_members
|
|
This should fix #104400 |
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/prefer-member-initializer.cpp
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carlosgalvezp
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Aug 16, 2025
v1nh1shungry
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…positive for inherited members in class templates
```cpp
struct Base {
int m;
};
template <class T>
struct Derived : Base {
Derived() { m = 0; }
};
```
would previously generate the following output:
```
<source>:7:15: warning: 'm' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
7 | Derived() { m = 0; }
| ^~~~~~
| : m(0)
```
This patch fixes this false positive.
v1nh1shungry
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/169/builds/14124 Here is the relevant piece of the build log for the reference |
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would previously generate the following output:
This patch fixes this false positive.
Note that before this patch the checker won't give false positive for
and the constructor's AST is
so
isAssignmentToMemberOfwould return empty due tollvm-project/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
Lines 118 to 119 in f0967fc
Fixes #104400