[PATCH] D74692: [clang-tidy] Make bugprone-use-after-move ignore std::move for const values

[Zinovy Nis via Phabricator via cfe-commits]

zinovy.nis updated this revision to Diff 246628.
zinovy.nis added a comment.

Warning on use after move is still generated. But there's also an additional note

> std::move of the const expression has no effect; remove std::move() or make the variable non-const




CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74692/new/

https://reviews.llvm.org/D74692

Files:
  clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
  clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
@@ -129,6 +129,16 @@
   // CHECK-NOTES: [[@LINE-3]]:15: note: move occurred here
 }
 
+void simpleConst() {
+  const A a;
+  a.foo();
+  A other_a = std::move(a);
+  a.foo();
+  // CHECK-NOTES: [[@LINE-1]]:3: warning: 'a' used after it was moved
+  // CHECK-NOTES: [[@LINE-3]]:15: note: move occurred here
+  // CHECK-NOTES: [[@LINE-6]]:11: note: std::move of the const expression {{.*}}
+}
+
 // A warning should only be emitted for one use-after-move.
 void onlyFlagOneUseAfterMove() {
   A a;
@@ -316,6 +326,7 @@
       a.foo();
       // CHECK-NOTES: [[@LINE-1]]:7: warning: 'a' used after it was moved
       // CHECK-NOTES: [[@LINE-3]]:7: note: move occurred here
+      // CHECK-NOTES: [[@LINE-6]]:7: note: std::move of the const expression {{.*}}
     };
   }
   // This is just as true if the variable was declared inside the lambda.
@@ -723,12 +734,14 @@
     passByConstPointer(&a);
     // CHECK-NOTES: [[@LINE-1]]:25: warning: 'a' used after it was moved
     // CHECK-NOTES: [[@LINE-3]]:5: note: move occurred here
+    // CHECK-NOTES: [[@LINE-5]]:13: note: std::move of the const expression {{.*}}
   }
   const A a;
   std::move(a);
   passByConstReference(a);
   // CHECK-NOTES: [[@LINE-1]]:24: warning: 'a' used after it was moved
   // CHECK-NOTES: [[@LINE-3]]:3: note: move occurred here
+  // CHECK-NOTES: [[@LINE-5]]:11: note: std::move of the const expression {{.*}}
 }
 
 // Clearing a standard container using clear() is treated as a
Index: clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -393,6 +393,13 @@
                 "the use happens in a later loop iteration than the move",
                 DiagnosticIDs::Note);
   }
+  if (MoveArg->getType().isConstQualified()) {
+    SourceLocation MoveArgLoc = MoveArg->getDecl()->getLocation();
+    Check->diag(MoveArgLoc,
+                "std::move of the const expression has no effect; "
+                "remove std::move() or make the variable non-const",
+                DiagnosticIDs::Note);
+  }
 }
 
 void UseAfterMoveCheck::registerMatchers(MatchFinder *Finder) {


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