[clang-tools-extra] ae28297 - [clang-tidy] Fix readability-else-after-return for [[likely]]/[[unlikely]] if (#184684)

[via cfe-commits]

Author: Berkay Sahin
Date: 2026-03-08T13:58:03-07:00
New Revision: ae282974b8a40e20a4c55dfffba84d24db843d74

URL: https://github.com/llvm/llvm-project/commit/ae282974b8a40e20a4c55dfffba84d24db843d74
DIFF: https://github.com/llvm/llvm-project/commit/ae282974b8a40e20a4c55dfffba84d24db843d74.diff

LOG: [clang-tidy] Fix readability-else-after-return for [[likely]]/[[unlikely]] if (#184684)

Following the PR #181878 I have noticed a false negative when if is
attributed.

Repro:

```cpp
void f()
{
    if (true) {
        return;
    } else {
        // Warns as expected
    }

    if (true) [[likely]] {
        return;
    } else {
        // False-negative
    }
}
```

Godbolt: https://godbolt.org/z/cvGdovjhx

Added: 
    clang-tools-extra/test/clang-tidy/checkers/readability/else-after-return-cxx20.cpp

Modified: 
    clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
    clang-tools-extra/docs/ReleaseNotes.rst

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp b/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
index 7e93d619e2a9f..74221163f3efa 100644
--- a/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
@@ -178,8 +178,9 @@ void ElseAfterReturnCheck::registerMatchers(MatchFinder *Finder) {
 
   const auto IfWithInterruptingThenElse =
       ifStmt(unless(isConstexpr()), unless(isConsteval()),
-             hasThen(stmt(anyOf(InterruptsControlFlow,
-                                compoundStmt(has(InterruptsControlFlow))))),
+             hasThen(stripLabelLikeStatements(
+                 stmt(anyOf(InterruptsControlFlow,
+                            compoundStmt(has(InterruptsControlFlow)))))),
              hasElse(stmt().bind("else")))
           .bind("if");
 

diff  --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 9f4d7e6923fa0..6e1a116a30bf8 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -299,8 +299,13 @@ Changes in existing checks
   when a member expression has a non-identifier name.
 
 - Improved :doc:`readability-else-after-return
-  <clang-tidy/checks/readability/else-after-return>` check by fixing missed
-  diagnostics when ``if`` statements appear in unbraced ``switch`` case labels.
+  <clang-tidy/checks/readability/else-after-return>` check:
+
+  - Fixed missed diagnostics when ``if`` statements appear in unbraced
+    ``switch`` case labels.
+
+  - Added support for handling attributed ``if`` then-branches such as
+    ``[[likely]]`` and ``[[unlikely]]``.
 
 - Improved :doc:`readability-enum-initial-value
   <clang-tidy/checks/readability/enum-initial-value>` check: the warning message

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/readability/else-after-return-cxx20.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/else-after-return-cxx20.cpp
new file mode 100644
index 0000000000000..589d2b6e2bb68
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/else-after-return-cxx20.cpp
@@ -0,0 +1,41 @@
+// RUN: %check_clang_tidy -std=c++20-or-later %s readability-else-after-return %t
+
+void g();
+
+void f() {
+  if (true) [[likely]] {
+    return;
+  } else { // comment-0
+      // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not use 'else' after 'return'
+      // CHECK-FIXES: {{^}}     } // comment-0
+  }
+
+  if (false) [[unlikely]] {
+    return;
+  } else { // comment-1
+      // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not use 'else' after 'return'
+      // CHECK-FIXES: {{^}}     } // comment-1
+  }
+
+  if (true) [[likely]]
+    return;
+  else // comment-2
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use 'else' after 'return'
+    // CHECK-FIXES: {{^}}  else // comment-2
+    int _ = 10;
+
+  if (false)
+    return;
+  else [[likely]] { // comment-3
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use 'else' after 'return'
+    // CHECK-FIXES: {{^}}  {{[[][[]}}likely{{[]][]]}} { // comment-3
+    int _ = 31;
+  }
+
+  if (true)
+    return;
+  else [[unlikely]]  // comment-4
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use 'else' after 'return'
+    // CHECK-FIXES: {{^}}  {{[[][[]}}unlikely{{[]][]]}} // comment-4
+    g();
+}