[PATCH] D119165: [clang-tidy] Add processing lambda captures at bugprone-use-after-move check

[Ivan Murashko via Phabricator via cfe-commits]

ivanmurashko created this revision.
ivanmurashko added reviewers: alexfh, sammccall, mboehme, aaron.ballman.
ivanmurashko added projects: clang, clang-tools-extra.
Herald added subscribers: carlosgalvezp, xazax.hun.
ivanmurashko requested review of this revision.
Herald added a subscriber: cfe-commits.

The diff adds processing for `std::move` inside lambda captures at `bugprone-use-after-move` check. Especially it detects invalid `std::move` inside following code

  int foo() {
    int a = 0;
    auto fun = [aa = std::move(a)]{
      return aa;
    };
    return a;
  }

Test Plan

  ./bin/llvm-lit -v  ../clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D119165

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
@@ -1350,3 +1350,18 @@
 private:
   std::string val_;
 };
+
+// Check std::move usage inside lambda captures
+int lambdaCaptures() {
+  int a = 0;
+  int b = 0;
+  int c = 0;
+  auto foo = [aa = std::move(a), bb = std::move(b), cc = c] {
+    // CHECK-NOTES: [[@LINE+6]]:10: warning: 'a' used after it was moved
+    // CHECK-NOTES: [[@LINE-2]]:20: note: move occurred here
+    // CHECK-NOTES: [[@LINE+4]]:14: warning: 'b' used after it was moved
+    // CHECK-NOTES: [[@LINE-4]]:39: note: move occurred here
+    return aa + bb + cc;
+  };
+  return a + b + c;
+};
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
@@ -397,11 +397,13 @@
 }
 
 void UseAfterMoveCheck::registerMatchers(MatchFinder *Finder) {
-  auto CallMoveMatcher =
+  auto AncestorMatcher =
+      anyOf(hasAncestor(lambdaExpr().bind("containing-lambda")),
+            hasAncestor(functionDecl().bind("containing-func")));
+
+  auto BaseMoveMatcher =
       callExpr(callee(functionDecl(hasName("::std::move"))), argumentCountIs(1),
                hasArgument(0, declRefExpr().bind("arg")),
-               anyOf(hasAncestor(lambdaExpr().bind("containing-lambda")),
-                     hasAncestor(functionDecl().bind("containing-func"))),
                unless(inDecltypeOrTemplateArg()),
                // try_emplace is a common maybe-moving function that returns a
                // bool to tell callers whether it moved. Ignore std::move inside
@@ -411,6 +413,16 @@
                    callee(cxxMethodDecl(hasName("try_emplace")))))))
           .bind("call-move");
 
+  auto CallMoveMatcherLambda = lambdaExpr(
+      forEachLambdaCapture(lambdaCapture(capturesVar(varDecl(
+          hasInitializer(expr(ignoringParenImpCasts(BaseMoveMatcher))))))),
+      AncestorMatcher);
+
+  Finder->addMatcher(CallMoveMatcherLambda, this);
+
+  auto CallMoveMatcherNoLambda =
+      expr(ignoringParenImpCasts(BaseMoveMatcher), AncestorMatcher);
+
   Finder->addMatcher(
       traverse(
           TK_AsIs,
@@ -418,7 +430,7 @@
           // for the direct ancestor of the std::move() that isn't one of the
           // node types ignored by ignoringParenImpCasts().
           stmt(
-              forEach(expr(ignoringParenImpCasts(CallMoveMatcher))),
+              forEach(CallMoveMatcherNoLambda),
               // Don't allow an InitListExpr to be the moving call. An
               // InitListExpr has both a syntactic and a semantic form, and the
               // parent-child relationships are different between the two. This


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