[PATCH] D67292: [clang-tidy] Fix bug in bugprone-use-after-move check

[Yitzhak Mandelbaum via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
ymandel marked an inline comment as done.
Closed by commit rL371396: [clang-tidy] Fix bug in bugprone-use-after-move check (authored by ymandel, committed by ).
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Changed prior to commit:
  https://reviews.llvm.org/D67292?vs=219152&id=219334#toc

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67292/new/

https://reviews.llvm.org/D67292

Files:
  clang-tools-extra/trunk/clang-tidy/utils/ExprSequence.cpp
  clang-tools-extra/trunk/test/clang-tidy/bugprone-use-after-move.cpp


Index: clang-tools-extra/trunk/clang-tidy/utils/ExprSequence.cpp
===================================================================
--- clang-tools-extra/trunk/clang-tidy/utils/ExprSequence.cpp
+++ clang-tools-extra/trunk/clang-tidy/utils/ExprSequence.cpp
@@ -145,17 +145,24 @@
         return ForRange->getBody();
     } else if (const auto *TheIfStmt = dyn_cast<IfStmt>(Parent)) {
       // If statement:
-      // - Sequence init statement before variable declaration.
+      // - Sequence init statement before variable declaration, if present;
+      //   before condition evaluation, otherwise.
       // - Sequence variable declaration (along with the expression used to
       //   initialize it) before the evaluation of the condition.
-      if (S == TheIfStmt->getInit())
-        return TheIfStmt->getConditionVariableDeclStmt();
+      if (S == TheIfStmt->getInit()) {
+        if (TheIfStmt->getConditionVariableDeclStmt() != nullptr)
+          return TheIfStmt->getConditionVariableDeclStmt();
+        return TheIfStmt->getCond();
+      }
       if (S == TheIfStmt->getConditionVariableDeclStmt())
         return TheIfStmt->getCond();
     } else if (const auto *TheSwitchStmt = dyn_cast<SwitchStmt>(Parent)) {
       // Ditto for switch statements.
-      if (S == TheSwitchStmt->getInit())
-        return TheSwitchStmt->getConditionVariableDeclStmt();
+      if (S == TheSwitchStmt->getInit()) {
+        if (TheSwitchStmt->getConditionVariableDeclStmt() != nullptr)
+          return TheSwitchStmt->getConditionVariableDeclStmt();
+        return TheSwitchStmt->getCond();
+      }
       if (S == TheSwitchStmt->getConditionVariableDeclStmt())
         return TheSwitchStmt->getCond();
     } else if (const auto *TheWhileStmt = dyn_cast<WhileStmt>(Parent)) {
Index: clang-tools-extra/trunk/test/clang-tidy/bugprone-use-after-move.cpp
===================================================================
--- clang-tools-extra/trunk/test/clang-tidy/bugprone-use-after-move.cpp
+++ clang-tools-extra/trunk/test/clang-tidy/bugprone-use-after-move.cpp
@@ -1182,7 +1182,10 @@
 
 // If a variable is declared in an if, while or switch statement, the init
 // statement (for if and switch) is sequenced before the variable declaration,
-// which in turn is sequenced before the evaluation of the condition.
+// which in turn is sequenced before the evaluation of the condition. We place
+// all tests inside a for loop to ensure that the checker understands the
+// sequencing. If it didn't, then the loop would trigger the "moved twice"
+// logic.
 void ifWhileAndSwitchSequenceInitDeclAndCondition() {
   for (int i = 0; i < 10; ++i) {
     A a1;
@@ -1192,15 +1195,44 @@
   }
   for (int i = 0; i < 10; ++i) {
     A a1;
+    if (A a2 = std::move(a1); a2) {
+      std::move(a2);
+    }
+  }
+  for (int i = 0; i < 10; ++i) {
+    A a1;
     if (A a2 = std::move(a1); A a3 = std::move(a2)) {
       std::move(a3);
     }
   }
+  for (int i = 0; i < 10; ++i) {
+    // init followed by condition with move, but without variable declaration.
+    if (A a1; A(std::move(a1)).getInt() > 0) {}
+  }
+  for (int i = 0; i < 10; ++i) {
+    if (A a1; A(std::move(a1)).getInt() > a1.getInt()) {}
+    // CHECK-NOTES: [[@LINE-1]]:43: warning: 'a1' used after it was moved
+    // CHECK-NOTES: [[@LINE-2]]:15: note: move occurred here
+    // CHECK-NOTES: [[@LINE-3]]:43: note: the use and move are unsequenced
+  }
+  for (int i = 0; i < 10; ++i) {
+    A a1;
+    if (A a2 = std::move(a1); A(a1) > 0) {}
+    // CHECK-NOTES: [[@LINE-1]]:33: warning: 'a1' used after it was moved
+    // CHECK-NOTES: [[@LINE-2]]:16: note: move occurred here
+  }
   while (A a = A()) {
     std::move(a);
   }
   for (int i = 0; i < 10; ++i) {
     A a1;
+    switch (A a2 = std::move(a1); a2) {
+      case true:
+        std::move(a2);
+    }
+  }
+  for (int i = 0; i < 10; ++i) {
+    A a1;
     switch (A a2 = a1; A a3 = std::move(a2)) {
       case true:
         std::move(a3);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D67292.219334.patch
Type: text/x-patch
Size: 3978 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20190909/0565bbda/attachment.bin>