Hi,
When doing something like this:
const int *CI;
int *I;
*(test ? I : CI) = 0
clang currently doesn't put the combined qualifiers on the output type, which
means that the assignment is allowed. I believe this patch implements correct
C99 semantics (and sane behaviour for non-CVR type qualifiers).
Could someone review it please?
Thanks.
Tim.
commit 88d5293ed4ecdf152d5e1025cd0c55eb46985eb8
Author: Tim Northover <[email protected]>
Date: Sat Mar 31 19:54:56 2012 +0100
Implement merging of types in conditional expressions
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 97cb647..130406c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -4567,8 +4567,28 @@ static QualType checkConditionalPointerCompatibility(Sema &S, ExprResult &LHS,
rhptee = RHSTy->castAs<PointerType>()->getPointeeType();
}
- if (!S.Context.typesAreCompatible(lhptee.getUnqualifiedType(),
- rhptee.getUnqualifiedType())) {
+ // C99 6.5.15p6: If both operands are pointers to compatible types or to
+ // differently qualified versions of compatible types, the result type is
+ // a pointer to an appropriately qualified version of the composite
+ // type.
+
+ // Only CVR-qualifiers exist in the standard, and the differently-qualified
+ // clause doesn't make sense for our extensions. E.g. address space 2 should
+ // be incompatible with address space 3: they may live on different devices or
+ // anything.
+ Qualifiers lhQual = lhptee.getQualifiers();
+ Qualifiers rhQual = rhptee.getQualifiers();
+
+ unsigned MergedCVRQual = lhQual.getCVRQualifiers() | rhQual.getCVRQualifiers();
+ lhQual.removeCVRQualifiers();
+ rhQual.removeCVRQualifiers();
+
+ lhptee = S.Context.getQualifiedType(lhptee.getUnqualifiedType(), lhQual);
+ rhptee = S.Context.getQualifiedType(rhptee.getUnqualifiedType(), rhQual);
+
+ QualType CompositeTy = S.Context.mergeTypes(lhptee, rhptee);
+
+ if (CompositeTy.isNull()) {
S.Diag(Loc, diag::warn_typecheck_cond_incompatible_pointers)
<< LHSTy << RHSTy << LHS.get()->getSourceRange()
<< RHS.get()->getSourceRange();
@@ -4582,16 +4602,12 @@ static QualType checkConditionalPointerCompatibility(Sema &S, ExprResult &LHS,
}
// The pointer types are compatible.
- // C99 6.5.15p6: If both operands are pointers to compatible types *or* to
- // differently qualified versions of compatible types, the result type is
- // a pointer to an appropriately qualified version of the *composite*
- // type.
- // FIXME: Need to calculate the composite type.
- // FIXME: Need to add qualifiers
+ QualType ResultTy = CompositeTy.withCVRQualifiers(MergedCVRQual);
+ ResultTy = S.Context.getPointerType(ResultTy);
- LHS = S.ImpCastExprToType(LHS.take(), LHSTy, CK_BitCast);
- RHS = S.ImpCastExprToType(RHS.take(), LHSTy, CK_BitCast);
- return LHSTy;
+ LHS = S.ImpCastExprToType(LHS.take(), ResultTy, CK_BitCast);
+ RHS = S.ImpCastExprToType(RHS.take(), ResultTy, CK_BitCast);
+ return ResultTy;
}
/// \brief Return the resulting type when the operands are both block pointers.
diff --git a/test/Sema/conditional-expr.c b/test/Sema/conditional-expr.c
index 436ecdb..541b54a 100644
--- a/test/Sema/conditional-expr.c
+++ b/test/Sema/conditional-expr.c
@@ -60,6 +60,21 @@ void foo() {
test0 = test0 ? EVal : test1; // expected-warning {{operand of ? changes signedness: 'int' to 'unsigned long'}}
test0 = test0 ? test1 : EVal; // expected-warning {{operand of ? changes signedness: 'int' to 'unsigned long'}}
+ const int *lhs_const;
+ int *rhs_nonconst;
+ *(test0 ? lhs_const : rhs_nonconst) = 42; // expected-error {{read-only variable is not assignable}}
+
+ // The composite type here should be "int (*)[12]", fine for the sizeof
+ int (*incomplete)[];
+ int (*complete)[12];
+ sizeof(*(test0 ? incomplete : complete)); // expected-warning {{expression result unused}}
+
+ int __attribute__((address_space(2))) *adr2;
+ int __attribute__((address_space(3))) *adr3;
+ test0 ? adr2 : adr3; // expected-warning {{pointer type mismatch}} expected-warning {{expression result unused}}
+
+ // Make sure address-space mask ends up in the result type
+ (test0 ? (test0 ? adr2 : adr2) : rhs_nonconst); // expected-warning {{pointer type mismatch}} expected-warning {{expression result unused}}
}
int Postgresql() {_______________________________________________
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