[clang-tidy] Fixed crash 44745 in readability-else-after-return

[njames93]

Summary

Fixes readability-else-after-return crashes

[njames93]

• new line

[merge_guards_bot]

Unit tests: pass. 62371 tests passed, 0 failed and 839 were skipped.

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

[merge_guards_bot]

Unit tests: pass. 62371 tests passed, 0 failed and 839 were skipped.

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

[alexfh]

LG. Thanks for the fix!

clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp

 static const char ReturnStr[] = "return";
 static const char ContinueStr[] = "continue";
 static const char BreakStr[] = "break";
 static const char ThrowStr[] = "throw";
 static const char WarningMessage[] = "do not use 'else' after '%0'";
 static const char WarnOnUnfixableStr[] = "WarnOnUnfixable";
 
 const DeclRefExpr *findUsage(const Stmt *Node, int64_t DeclIdentifier) {
+  if (!Node)
+    return nullptr;
   if (const auto *DeclRef = dyn_cast<DeclRefExpr>(Node)) {
     if (DeclRef->getDecl()->getID() == DeclIdentifier) {
       return DeclRef;
     }
   } else {
     for (const Stmt *ChildNode : Node->children()) {
       if (const DeclRefExpr *Result = findUsage(ChildNode, DeclIdentifier)) {
         return Result;
       }
     }
   }
   return nullptr;
 }
 
 const DeclRefExpr *
 findUsageRange(const Stmt *Node,
                const llvm::iterator_range<int64_t *> &DeclIdentifiers) {
+  if (!Node)
+    return nullptr;
   if (const auto *DeclRef = dyn_cast<DeclRefExpr>(Node)) {
     if (llvm::is_contained(DeclIdentifiers, DeclRef->getDecl()->getID())) {
       return DeclRef;
     }
   } else {
     for (const Stmt *ChildNode : Node->children()) {
       if (const DeclRefExpr *Result =
               findUsageRange(ChildNode, DeclIdentifiers)) {

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

if (int b = a; b > 1) { // comment-18
     // CHECK-FIXES-NEXT: {{^}}if ( b > 1) { // comment-18
     return a;
   } else { // comment-18
            // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not use 'else' after 'return'
            // CHECK-FIXES: {{^}}  } // comment-18
     return b;
   }
 }
+
+void test_B44745() {
+  // This is the actual minimum test case for the crash in bug 44745. We aren't
+  // too worried about the warning or fix here, more we don't want a crash.
+  // CHECK-MESSAGES: :[[@LINE+3]]:5: warning: do not use 'else' after 'return' [readability-else-after-return]
+  if (auto X = false) {
+    return;
+  } else {
+    for (;;) {
+    }
+  }
+  return;
+}