[clang-tools-extra] 6874dfc - [clang-tidy] Fix bugprone-use-after-move when move is in noexcept operator

[via cfe-commits]

Author: Nathan
Date: 2020-01-28T00:39:07Z
New Revision: 6874dfce3aef4a0d85fc9d45f4c9c3d90cfcbf6e

URL: https://github.com/llvm/llvm-project/commit/6874dfce3aef4a0d85fc9d45f4c9c3d90cfcbf6e
DIFF: https://github.com/llvm/llvm-project/commit/6874dfce3aef4a0d85fc9d45f4c9c3d90cfcbf6e.diff

LOG: [clang-tidy] Fix bugprone-use-after-move when move is in noexcept operator

Summary: Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=44667 | noexcept operator misinterpreted as being evaluated ]].

Reviewers: aaron.ballman, alexfh, JonasToth, hokein, gribozavr2

Reviewed By: gribozavr2

Subscribers: merge_guards_bot, Quuxplusone, xazax.hun, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D73441

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
index 2a5c5fa414d2..6c855440aa55 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -8,6 +8,10 @@
 
 #include "UseAfterMoveCheck.h"
 
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprConcepts.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Analysis/CFG.h"
 #include "clang/Lex/Lexer.h"
 
@@ -23,6 +27,23 @@ namespace bugprone {
 
 namespace {
 
+AST_MATCHER(Expr, hasUnevaluatedContext) {
+  if (isa<CXXNoexceptExpr>(Node) || isa<RequiresExpr>(Node))
+    return true;
+  if (const auto *UnaryExpr = dyn_cast<UnaryExprOrTypeTraitExpr>(&Node)) {
+    switch (UnaryExpr->getKind()) {
+    case UETT_SizeOf:
+    case UETT_AlignOf:
+      return true;
+    default:
+      return false;
+    }
+  }
+  if (const auto *TypeIDExpr = dyn_cast<CXXTypeidExpr>(&Node))
+    return !TypeIDExpr->isPotentiallyEvaluated();
+  return false;
+}
+
 /// Contains information about a use-after-move.
 struct UseAfterMove {
   // The DeclRefExpr that constituted the use of the object.
@@ -77,7 +98,8 @@ class UseAfterMoveFinder {
 static StatementMatcher inDecltypeOrTemplateArg() {
   return anyOf(hasAncestor(typeLoc()),
                hasAncestor(declRefExpr(
-                   to(functionDecl(ast_matchers::isTemplateInstantiation())))));
+                   to(functionDecl(ast_matchers::isTemplateInstantiation())))),
+               hasAncestor(expr(hasUnevaluatedContext())));
 }
 
 UseAfterMoveFinder::UseAfterMoveFinder(ASTContext *TheContext)

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
index a28c901308cc..8a69ca42a072 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone-use-after-move.cpp
@@ -1270,4 +1270,32 @@ class C : T, B {
     C c;
   }
 };
+} // namespace PR33020
+
+namespace UnevalContext {
+struct Foo {};
+void noExcept() {
+  Foo Bar;
+  (void) noexcept(Foo{std::move(Bar)});
+  Foo Other{std::move(Bar)};
 }
+void sizeOf() {
+  Foo Bar;
+  (void)sizeof(Foo{std::move(Bar)});
+  Foo Other{std::move(Bar)};
+}
+void alignOf() {
+  Foo Bar;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wgnu-alignof-expression"
+  (void)alignof(Foo{std::move(Bar)});
+#pragma clang diagnostic pop
+  Foo Other{std::move(Bar)};
+}
+void typeId() {
+  Foo Bar;
+  // error: you need to include <typeinfo> before using the 'typeid' operator
+  // (void) typeid(Foo{std::move(Bar)}).name();
+  Foo Other{std::move(Bar)};
+}
+} // namespace UnevalContext