[clang-tools-extra] b751719 - [clang-tidy] Adds do-while support to performance-inefficient-string-concatenation (#186607)

[via cfe-commits]

Author: Berkay Sahin
Date: 2026-03-15T19:31:44+08:00
New Revision: b751719170fdba8c0b9c07b5b6a598e95baba580

URL: https://github.com/llvm/llvm-project/commit/b751719170fdba8c0b9c07b5b6a598e95baba580
DIFF: https://github.com/llvm/llvm-project/commit/b751719170fdba8c0b9c07b5b6a598e95baba580.diff

LOG: [clang-tidy] Adds do-while support to performance-inefficient-string-concatenation (#186607)

Closes #186362

---------

Co-authored-by: Victor Chernyakin <chernyakin.victor.j at outlook.com>
Co-authored-by: EugeneZelenko <eugene.zelenko at gmail.com>

Added: 
    

Modified: 
    clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
    clang-tools-extra/docs/ReleaseNotes.rst
    clang-tools-extra/docs/clang-tidy/checks/performance/inefficient-string-concatenation.rst
    clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-string-concatenation.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp b/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
index 92e3220fdb817..1067fca289a2c 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
@@ -53,11 +53,11 @@ void InefficientStringConcatenationCheck::registerMatchers(
     Finder->addMatcher(cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator)),
                        this);
   } else {
-    Finder->addMatcher(
-        cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator),
-                            hasAncestor(stmt(anyOf(cxxForRangeStmt(),
-                                                   whileStmt(), forStmt())))),
-        this);
+    Finder->addMatcher(cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator),
+                                           hasAncestor(stmt(anyOf(
+                                               cxxForRangeStmt(), whileStmt(),
+                                               forStmt(), doStmt())))),
+                       this);
   }
 }
 

diff  --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 751550c2e0940..059e48b512adf 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -321,6 +321,11 @@ Changes in existing checks
 
   - Fixes false negatives when using ``std::set`` from ``libstdc++``.
 
+- Improved :doc:`performance-inefficient-string-concatenation
+  <clang-tidy/checks/performance/inefficient-string-concatenation>` check by
+  adding support for detecting inefficient string concatenation in ``do-while``
+  loops.
+
 - Improved :doc:`performance-inefficient-vector-operation
   <clang-tidy/checks/performance/inefficient-vector-operation>` check by
   correctly handling vector-like classes when ``push_back``/``emplace_back`` are

diff  --git a/clang-tools-extra/docs/clang-tidy/checks/performance/inefficient-string-concatenation.rst b/clang-tools-extra/docs/clang-tidy/checks/performance/inefficient-string-concatenation.rst
index 92b6b4e0370d6..56f6b9640080d 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/performance/inefficient-string-concatenation.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/performance/inefficient-string-concatenation.rst
@@ -55,5 +55,5 @@ Options
 
 .. option:: StrictMode
 
-   When `false`, the check will only check the string usage in ``while``, ``for``
-   and ``for-range`` statements. Default is `false`.
+   When `false`, the check will only warn on inefficient string usage inside loops.
+   Default is `false`.

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-string-concatenation.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-string-concatenation.cpp
index 72080ed39e59b..adc37e4c4bedf 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-string-concatenation.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-string-concatenation.cpp
@@ -32,5 +32,11 @@ int main() {
     f(mystr2 + mystr1);
     mystr1 = g(mystr1);
   }
+
+  do {
+    mystr1 = mystr1 + mystr2;
+    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: string concatenation results in allocation of unnecessary temporary strings; consider using 'operator+=' or 'string::append()' instead
+  } while (0);
+
   return 0;
 }