diff options
| -rw-r--r-- | clang/lib/AST/Expr.cpp | 16 | ||||
| -rw-r--r-- | clang/lib/Sema/SemaExpr.cpp | 10 | ||||
| -rw-r--r-- | clang/test/Sema/stmt_exprs.c | 12 |
3 files changed, 31 insertions, 7 deletions
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp index 9b4de2bf4e8..d31bde283b1 100644 --- a/clang/lib/AST/Expr.cpp +++ b/clang/lib/AST/Expr.cpp @@ -347,10 +347,18 @@ bool Expr::hasLocalSideEffect() const { return true; case ObjCMessageExprClass: return true; - case StmtExprClass: - // TODO: check the inside of the statement expression - return true; - + case StmtExprClass: { + // Statement exprs don't logically have side effects themselves, but are + // sometimes used in macros in ways that give them a type that is unused. + // For example ({ blah; foo(); }) will end up with a type if foo has a type. + // however, if the result of the stmt expr is dead, we don't want to emit a + // warning. + const CompoundStmt *CS = cast<StmtExpr>(this)->getSubStmt(); + if (!CS->body_empty()) + if (const Expr *E = dyn_cast<Expr>(CS->body_back())) + return E->hasLocalSideEffect(); + return false; + } case CastExprClass: // If this is a cast to void, check the operand. Otherwise, the result of // the cast is unused. diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 25a86fabdb7..bb5ed509e54 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -2334,9 +2334,15 @@ Sema::ExprResult Sema::ActOnStmtExpr(SourceLocation LPLoc, StmtTy *substmt, // as the type of the stmtexpr. QualType Ty = Context.VoidTy; - if (!Compound->body_empty()) - if (Expr *LastExpr = dyn_cast<Expr>(Compound->body_back())) + if (!Compound->body_empty()) { + Stmt *LastStmt = Compound->body_back(); + // If LastStmt is a label, skip down through into the body. + while (LabelStmt *Label = dyn_cast<LabelStmt>(LastStmt)) + LastStmt = Label->getSubStmt(); + + if (Expr *LastExpr = dyn_cast<Expr>(LastStmt)) Ty = LastExpr->getType(); + } return new StmtExpr(Compound, Ty, LPLoc, RPLoc); } diff --git a/clang/test/Sema/stmt_exprs.c b/clang/test/Sema/stmt_exprs.c index 8165cf03aa4..ee835a355dc 100644 --- a/clang/test/Sema/stmt_exprs.c +++ b/clang/test/Sema/stmt_exprs.c @@ -1,4 +1,4 @@ -// RUN: clang %s -fsyntax-only +// RUN: clang %s -fsyntax-only -verify typedef unsigned __uint32_t; @@ -10,3 +10,13 @@ __extension__ ({ register __uint32_t __X = (x); \ int test(int _x) { return (__byte_swap_int_var(_x)); } + +// PR2374 +int test2() { return ({L:5;}); } +int test3() { return ({ {5;} }); } // expected-error {{incompatible type returning 'void', expected 'int'}}\ + // expected-warning {{expression result unused}} +int test4() { return ({ ({5;}); }); } +int test5() { return ({L1: L2: L3: 5;}); } +int test6() { return ({5;}); } +void test7() { ({5;}); } // expected-warning {{expression result unused}} + |
