Implement PR4407 - missing warnings on case value overflow,
patch by Zhanyong Wan!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@84259 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index e8cd6b0..efa7e22 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -368,6 +368,21 @@
return false;
}
+/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
+/// potentially integral-promoted expression @p expr.
+static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
+ const ImplicitCastExpr *ImplicitCast =
+ dyn_cast_or_null<ImplicitCastExpr>(expr);
+ if (ImplicitCast != NULL) {
+ const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
+ QualType TypeBeforePromotion = ExprBeforePromotion->getType();
+ if (TypeBeforePromotion->isIntegralType()) {
+ return TypeBeforePromotion;
+ }
+ }
+ return expr->getType();
+}
+
Action::OwningStmtResult
Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
StmtArg Body) {
@@ -382,6 +397,16 @@
Expr *CondExpr = SS->getCond();
QualType CondType = CondExpr->getType();
+ // C++ 6.4.2.p2:
+ // Integral promotions are performed (on the switch condition).
+ //
+ // A case value unrepresentable by the original switch condition
+ // type (before the promotion) doesn't make sense, even when it can
+ // be represented by the promoted type. Therefore we need to find
+ // the pre-promotion type of the switch condition.
+ QualType CondTypeBeforePromotion =
+ GetTypeBeforeIntegralPromotion(CondExpr);
+
if (!CondExpr->isTypeDependent() &&
!CondType->isIntegerType()) { // C99 6.8.4.2p1
Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
@@ -395,8 +420,8 @@
= CondExpr->isTypeDependent() || CondExpr->isValueDependent();
unsigned CondWidth
= HasDependentValue? 0
- : static_cast<unsigned>(Context.getTypeSize(CondType));
- bool CondIsSigned = CondType->isSignedIntegerType();
+ : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
+ bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
// Accumulate all of the case values in a vector so that we can sort them
// and detect duplicates. This vector contains the APInt for the case after
diff --git a/test/Sema/switch.c b/test/Sema/switch.c
index 5999f34..122947e 100644
--- a/test/Sema/switch.c
+++ b/test/Sema/switch.c
@@ -68,3 +68,10 @@
}
}
+void test6() {
+ const char ch = 'a';
+ switch(ch) {
+ case 1234: // expected-warning {{overflow converting case value}}
+ break;
+ }
+}