[fuzzer] Do not generate void expressions in sizeof (#132)

Author: tonkosi

tools/fuzzer/constraints.cc

@@ -228,9 +228,7 @@ TypeConstraints TypeConstraints::allowed_to_point_to() const {
   }
 
   if (std::holds_alternative<AnyType>(ptr_types_)) {
-    TypeConstraints retval = TypeConstraints::all();
-    retval.scalar_types_[ScalarType::Void] = false;
-    return retval;
+    return TypeConstraints::all_non_void();
   }
 
   const auto* specific_types_ptr =

tools/fuzzer/constraints.h

@@ -92,9 +92,9 @@ class TypeConstraints {
     return retval;
   }
 
-  static TypeConstraints all() {
+  static TypeConstraints all_non_void() {
     TypeConstraints retval;
-    retval.scalar_types_ = ScalarMask::all_set();
+    retval.scalar_types_ = ~ScalarMask(ScalarType::Void);
     retval.tagged_types_ = AnyType{};
     retval.ptr_types_ = AnyType{};
     retval.array_types_ = AnyType{};

tools/fuzzer/constraints_test.cc

@@ -25,7 +25,7 @@ TEST(Constraints, ScalarValues) {
   TypeConstraints float_only = FLOAT_TYPES;
   TypeConstraints int_only = INT_TYPES;
 
-  TypeConstraints any = TypeConstraints::all();
+  TypeConstraints any = TypeConstraints::all_non_void();
   TypeConstraints none;
 
   PointerType void_ptr_type{QualifiedType(ScalarType::Void)};
@@ -85,7 +85,7 @@ TEST(Constraints, TaggedTypes) {
   EXPECT_THAT(test_struct.allows_non_void_pointer(), IsFalse());
   EXPECT_THAT(test_struct.allows_void_pointer(), IsFalse());
 
-  TypeConstraints any = TypeConstraints::all();
+  TypeConstraints any = TypeConstraints::all_non_void();
   TypeConstraints none;
 
   EXPECT_THAT(any.allows_tagged_types(), IsTrue());
@@ -159,7 +159,7 @@ TEST(Constraints, PointerTypes) {
   // void types :(
   EXPECT_THAT(void_constraints.allows_any_of(ScalarType::Void), IsFalse());
 
-  TypeConstraints any = TypeConstraints::all();
+  TypeConstraints any = TypeConstraints::all_non_void();
   TypeConstraints none;
 
   EXPECT_THAT(any.allows_type(const_int_ptr), IsTrue());
@@ -176,7 +176,7 @@ TEST(Constraints, EnumTypes) {
   EnumType unscoped_enum("UnscopedEnum", false);
   EnumType specific_enum("SpecificEnum", true);
 
-  TypeConstraints any = TypeConstraints::all();
+  TypeConstraints any = TypeConstraints::all_non_void();
   TypeConstraints none;
   TypeConstraints bool_ctx = TypeConstraints::all_in_bool_ctx();
   TypeConstraints only_specific = TypeConstraints(specific_enum);
@@ -217,7 +217,7 @@ TEST(Constraints, ArrayTypes) {
   ArrayType array_of_ptrs = ArrayType(int_ptr, 3);
   PointerType ptr_to_array = PointerType(QualifiedType(array_of_three));
 
-  TypeConstraints any = TypeConstraints::all();
+  TypeConstraints any = TypeConstraints::all_non_void();
   EXPECT_THAT(any.allows_type(array_of_three), IsTrue());
   EXPECT_THAT(any.allows_type(array_of_four), IsTrue());
   EXPECT_THAT(any.allows_type(array2d), IsTrue());

tools/fuzzer/expr_gen.cc

@@ -903,7 +903,7 @@ std::optional<Expr> ExprGenerator::gen_sizeof_expr_impl(
     return SizeofExpr(std::move(maybe_type.value()));
   }
 
-  auto maybe_expr = gen_with_weights(weights, TypeConstraints::all());
+  auto maybe_expr = gen_with_weights(weights, TypeConstraints::all_non_void());
   if (!maybe_expr.has_value()) {
     return {};
   }