[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
This revision was automatically updated to reflect the committed changes.
Closed by commit rG87d0aedaa285: [clang-tidy] Add
readability-reference-to-constructed-temporary check (authored by PiotrZSL).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146368/new/
https://reviews.llvm.org/D146368
Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& str("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -380,6 +380,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
`readability-simplify-boolean-expr `_, "Yes"
`readability-simplify-subscript-expr `_, "Yes"
`readability-static-accessed-through-instance `_, "Yes"
Index:
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
xgupta accepted this revision. xgupta added a comment. This revision is now accepted and ready to land. LGTM! Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
xgupta added a comment. This LGTM, I will wait for two days before accepting the revision in case other reviewers might have some more comments/suggestions. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL updated this revision to Diff 544205.
PiotrZSL marked an inline comment as done.
PiotrZSL added a comment.
Rename value to str in doc.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
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https://reviews.llvm.org/D146368
Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& str("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -379,6 +379,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
`readability-simplify-boolean-expr `_, "Yes"
`readability-simplify-subscript-expr `_, "Yes"
`readability-static-accessed-through-instance `_, "Yes"
Index: clang-tools-extra/docs/ReleaseNotes.rst
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL marked 2 inline comments as done.
PiotrZSL added inline comments.
Comment at:
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:18
+
+ const std::string& value("hello");
+
xgupta wrote:
> PiotrZSL wrote:
> > xgupta wrote:
> > > The below comment is not matching, do you want to write -
> > > `const std::string& str = std::string("hello");`
> > > ?
> > actually comment is +- fine, constructor to std::string will be called
> > anyway, and for compiler I think those 2 are equal.
> > Will verify.
> but you have written below `reference variable ``str`` is assigned a
> temporary object` and there is no str variable.
Ok, that's actually a bug. It's `value`.
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[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
xgupta added inline comments.
Comment at:
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:18
+
+ const std::string& value("hello");
+
PiotrZSL wrote:
> xgupta wrote:
> > The below comment is not matching, do you want to write -
> > `const std::string& str = std::string("hello");`
> > ?
> actually comment is +- fine, constructor to std::string will be called
> anyway, and for compiler I think those 2 are equal.
> Will verify.
but you have written below `reference variable ``str`` is assigned a temporary
object` and there is no str variable.
Repository:
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[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL updated this revision to Diff 544057.
PiotrZSL marked an inline comment as done.
PiotrZSL added a comment.
Update
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146368/new/
https://reviews.llvm.org/D146368
Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& value("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -379,6 +379,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
`readability-simplify-boolean-expr `_, "Yes"
`readability-simplify-subscript-expr `_, "Yes"
`readability-static-accessed-through-instance `_, "Yes"
Index: clang-tools-extra/docs/ReleaseNotes.rst
===
---
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL marked 4 inline comments as done. PiotrZSL added inline comments. Comment at: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:10 +This construction is often the result of multiple code refactorings or a lack +of developer knowledge, leading to confusion or subtle bugs. In most cases, +what the developer really wanted to do is create a new variable rather than xgupta wrote: > May be good to mention dangling references and resource leakage as potential > issues. There will be no dangling references and resource leakage because lifetime of temporary is extended by variable. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL added inline comments.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:39
+ ID) {
+ NotExtendedByDeclBoundToPredicate Predicate;
+ Predicate.ID = ID;
xgupta wrote:
> Can be written using direct initialization as
> `NotExtendedByDeclBoundToPredicate Predicate{ID};`
Yes, but I followed like others are done.
Comment at:
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:18
+
+ const std::string& value("hello");
+
xgupta wrote:
> The below comment is not matching, do you want to write -
> `const std::string& str = std::string("hello");`
> ?
actually comment is +- fine, constructor to std::string will be called anyway,
and for compiler I think those 2 are equal.
Will verify.
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[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
xgupta added inline comments.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:20
+
+struct NotExtendedByDeclBoundToPredicate {
+ bool operator()(const internal::BoundNodesMap ) const {
A comment might be good to describe this struct.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:22
+ bool operator()(const internal::BoundNodesMap ) const {
+const auto *Other = Nodes.getNode(ID).get();
+if (!Other)
This can be written as `const auto *Other = Nodes.getNodeAs(ID);`
following other patterns.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:39
+ ID) {
+ NotExtendedByDeclBoundToPredicate Predicate;
+ Predicate.ID = ID;
Can be written using direct initialization as
`NotExtendedByDeclBoundToPredicate Predicate{ID};`
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:63
+
+bool ReferenceToConstructedTemporaryCheck::isLanguageVersionSupported(
+const LangOptions ) const {
This part looks like boilerplate in the middle of a specific implementation.,
`isLanguageVersionSupported` is mostly in the header file.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:69
+std::optional
+ReferenceToConstructedTemporaryCheck::getCheckTraversalKind() const {
+ return TK_AsIs;
This part look like boilerplate in the middle of a specific implementation.,
getCheckTraversalKind() is mostly in the header file.
Comment at:
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:10
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
May be good to mention dangling references and resource leakage as potential
issues.
Comment at:
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst:18
+
+ const std::string& value("hello");
+
The below comment is not matching, do you want to write -
`const std::string& str = std::string("hello");`
?
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[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL added a comment. Ping Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL added a comment. Ping Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL added a comment. Ping Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL updated this revision to Diff 513693.
PiotrZSL added a comment.
Ping + Rebase
Repository:
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Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& value("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -366,6 +366,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
`readability-simplify-boolean-expr `_, "Yes"
`readability-simplify-subscript-expr `_, "Yes"
`readability-static-accessed-through-instance `_, "Yes"
Index: clang-tools-extra/docs/ReleaseNotes.rst
===
---
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL updated this revision to Diff 506399.
PiotrZSL marked 3 inline comments as done.
PiotrZSL added a comment.
Review comment fixes
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146368/new/
https://reviews.llvm.org/D146368
Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& value("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -363,6 +363,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
`readability-simplify-boolean-expr `_, "Yes"
`readability-simplify-subscript-expr `_, "Yes"
`readability-static-accessed-through-instance `_, "Yes"
Index: clang-tools-extra/docs/ReleaseNotes.rst
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
Eugene.Zelenko added inline comments.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:22
+ bool operator()(const internal::BoundNodesMap ) const {
+auto *Other = Nodes.getNode(ID).get();
+if (!Other)
`const auto *`.
Comment at:
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp:26
+
+auto Self = Node.get();
+if (!Self)
Ditto.
Comment at:
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp:31
+}
+
Excessive newline.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146368/new/
https://reviews.llvm.org/D146368
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[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL added a comment. There are 2 issues found in llvm repository: - llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp:721:22: warning: reference variable 'S' extends the lifetime of a just-constructed temporary object 'const StringRef', consider changing reference to value [readability-reference-to-constructed-temporary] - clang/lib/Sema/SemaChecking.cpp:10096:36: warning: reference variable 'AT2' extends the lifetime of a just-constructed temporary object 'const analyze_printf::ArgType', consider changing reference to value [readability-reference-to-constructed-temporary] Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D146368/new/ https://reviews.llvm.org/D146368 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D146368: [clang-tidy] Add readability-reference-to-constructed-temporary check
PiotrZSL created this revision.
Herald added subscribers: carlosgalvezp, xazax.hun.
Herald added a reviewer: njames93.
Herald added a project: All.
PiotrZSL requested review of this revision.
Herald added a project: clang-tools-extra.
Herald added a subscriber: cfe-commits.
Detects code where a temporary object is directly constructed by calling
a constructor or using an initializer list and immediately assigned to a
reference variable.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D146368
Files:
clang-tools-extra/clang-tidy/readability/CMakeLists.txt
clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.cpp
clang-tools-extra/clang-tidy/readability/ReferenceToConstructedTemporaryCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
===
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/readability/reference-to-constructed-temporary.cpp
@@ -0,0 +1,31 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-reference-to-constructed-temporary %t
+
+struct WithConstructor
+{
+WithConstructor(int, int);
+};
+
+struct WithoutConstructor
+{
+int a, b;
+};
+
+void test()
+{
+// CHECK-MESSAGES: :[[@LINE+1]]:27: warning: reference variable 'tmp1' extends the lifetime of a just-constructed temporary object 'const WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithConstructor& tmp1{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:30: warning: reference variable 'tmp2' extends the lifetime of a just-constructed temporary object 'const WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ const WithoutConstructor& tmp2{1,2};
+
+
+// CHECK-MESSAGES: :[[@LINE+1]]:22: warning: reference variable 'tmp3' extends the lifetime of a just-constructed temporary object 'WithConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithConstructor&& tmp3{1,2};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:25: warning: reference variable 'tmp4' extends the lifetime of a just-constructed temporary object 'WithoutConstructor', consider changing reference to value [readability-reference-to-constructed-temporary]
+ WithoutConstructor&& tmp4{1,2};
+
+ WithConstructor tmp5{1,2};
+ WithoutConstructor tmp6{1,2};
+}
+
Index: clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
===
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/readability/reference-to-constructed-temporary.rst
@@ -0,0 +1,32 @@
+.. title:: clang-tidy - readability-reference-to-constructed-temporary
+
+readability-reference-to-constructed-temporary
+==
+
+Detects C++ code where a reference variable is used to extend the lifetime of
+a temporary object that has just been constructed.
+
+This construction is often the result of multiple code refactorings or a lack
+of developer knowledge, leading to confusion or subtle bugs. In most cases,
+what the developer really wanted to do is create a new variable rather than
+extending the lifetime of a temporary object.
+
+Examples of problematic code include:
+
+.. code-block:: c++
+
+ const std::string& value("hello");
+
+ struct Point { int x; int y; };
+ const Point& p = { 1, 2 };
+
+In the first example, a ``const std::string&`` reference variable ``str`` is
+assigned a temporary object created by the ``std::string("hello")``
+constructor. In the second example, a ``const Point&`` reference variable ``p``
+is assigned an object that is constructed from an initializer list ``{ 1, 2 }``.
+Both of these examples extend the lifetime of the temporary object to the
+lifetime of the reference variable, which can make it difficult to reason about
+and may lead to subtle bugs or misunderstanding.
+
+To avoid these issues, it is recommended to change the reference variable to a
+(``const``) value variable.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -363,6 +363,7 @@
`readability-redundant-smartptr-get `_, "Yes"
`readability-redundant-string-cstr `_, "Yes"
`readability-redundant-string-init `_, "Yes"
+ `readability-reference-to-constructed-temporary `_,
