diff options
author | Daniel Jasper <djasper@google.com> | 2017-03-27 16:29:41 +0000 |
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committer | Daniel Jasper <djasper@google.com> | 2017-03-27 16:29:41 +0000 |
commit | 75f794b36977628281921472eaf4bc63d9cb336c (patch) | |
tree | 64749b2b91d56aff80d86947dea59a50a27ee068 | |
parent | 35e89432a6e23c582fb17636ef4908a022964b2e (diff) |
Look through CXXBindTemporaryExprs when checking CXXFunctionCastExprs
for unused values.
This fixes a regression caused by r298676, where constructor calls to
classes with non-trivial dtor were marked as unused if the first
argument is an initializer list. This is inconsistent (as the test
shows) and also warns on a reasonbly common code pattern where people
just call constructors to create and immediately destroy an object.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298853 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Sema/SemaStmt.cpp | 10 | ||||
-rw-r--r-- | test/SemaCXX/warn-unused-value.cpp | 6 |
2 files changed, 14 insertions, 2 deletions
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp index f393e3e794..4cf1ad9e1c 100644 --- a/lib/Sema/SemaStmt.cpp +++ b/lib/Sema/SemaStmt.cpp @@ -290,9 +290,15 @@ void Sema::DiagnoseUnusedExprResult(const Stmt *S) { DiagID = diag::warn_unused_property_expr; } else if (const CXXFunctionalCastExpr *FC = dyn_cast<CXXFunctionalCastExpr>(E)) { - if (isa<CXXConstructExpr>(FC->getSubExpr()) || - isa<CXXTemporaryObjectExpr>(FC->getSubExpr())) + const Expr *E = FC->getSubExpr(); + if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(E)) + E = TE->getSubExpr(); + if (isa<CXXTemporaryObjectExpr>(E)) return; + if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(E)) + if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl()) + if (!RD->getAttr<WarnUnusedAttr>()) + return; } // Diagnose "(void*) blah" as a typo for "(void) blah". else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) { diff --git a/test/SemaCXX/warn-unused-value.cpp b/test/SemaCXX/warn-unused-value.cpp index d6ec0fb5d1..98e2a4e863 100644 --- a/test/SemaCXX/warn-unused-value.cpp +++ b/test/SemaCXX/warn-unused-value.cpp @@ -59,11 +59,13 @@ struct Used { Used(); Used(int); Used(int, int); + ~Used() {} }; struct __attribute__((warn_unused)) Unused { Unused(); Unused(int); Unused(int, int); + ~Unused() {} }; void f() { Used(); @@ -72,6 +74,10 @@ void f() { Unused(); // expected-warning {{expression result unused}} Unused(1); // expected-warning {{expression result unused}} Unused(1, 1); // expected-warning {{expression result unused}} +#if __cplusplus >= 201103L // C++11 or later + Used({}); + Unused({}); // expected-warning {{expression result unused}} +#endif } } |