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llvm-project/clang/test/Analysis/more-dtors-cfg-output.cpp
Matheus Izvekov 15f3cd6bfc
[clang] Implement ElaboratedType sugaring for types written bare 
Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

---

Troubleshooting list to deal with any breakage seen with this patch:

1) The most likely effect one would see by this patch is a change in how
   a type is printed. The type printer will, by design and default,
   print types as written. There are customization options there, but
   not that many, and they mainly apply to how to print a type that we
   somehow failed to track how it was written. This patch fixes a
   problem where we failed to distinguish between a type
   that was written without any elaborated-type qualifiers,
   such as a 'struct'/'class' tags and name spacifiers such as 'std::',
   and one that has been stripped of any 'metadata' that identifies such,
   the so called canonical types.
   Example:
   ```
   namespace foo {
     struct A {};
     A a;
   };
   ```
   If one were to print the type of `foo::a`, prior to this patch, this
   would result in `foo::A`. This is how the type printer would have,
   by default, printed the canonical type of A as well.
   As soon as you add any name qualifiers to A, the type printer would
   suddenly start accurately printing the type as written. This patch
   will make it print it accurately even when written without
   qualifiers, so we will just print `A` for the initial example, as
   the user did not really write that `foo::` namespace qualifier.

2) This patch could expose a bug in some AST matcher. Matching types
   is harder to get right when there is sugar involved. For example,
   if you want to match a type against being a pointer to some type A,
   then you have to account for getting a type that is sugar for a
   pointer to A, or being a pointer to sugar to A, or both! Usually
   you would get the second part wrong, and this would work for a
   very simple test where you don't use any name qualifiers, but
   you would discover is broken when you do. The usual fix is to
   either use the matcher which strips sugar, which is annoying
   to use as for example if you match an N level pointer, you have
   to put N+1 such matchers in there, beginning to end and between
   all those levels. But in a lot of cases, if the property you want
   to match is present in the canonical type, it's easier and faster
   to just match on that... This goes with what is said in 1), if
   you want to match against the name of a type, and you want
   the name string to be something stable, perhaps matching on
   the name of the canonical type is the better choice.

3) This patch could expose a bug in how you get the source range of some
   TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
   which only looks at the given TypeLoc node. This patch introduces a new,
   and more common TypeLoc node which contains no source locations on itself.
   This is not an inovation here, and some other, more rare TypeLoc nodes could
   also have this property, but if you use getLocalSourceRange on them, it's not
   going to return any valid locations, because it doesn't have any. The right fix
   here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
   into the inner TypeLoc to get the source range if it doesn't find it on the
   top level one. You can use getLocalSourceRange if you are really into
   micro-optimizations and you have some outside knowledge that the TypeLocs you are
   dealing with will always include some source location.

4) Exposed a bug somewhere in the use of the normal clang type class API, where you
   have some type, you want to see if that type is some particular kind, you try a
   `dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
   ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
   Again, like 2), this would usually have been tested poorly with some simple tests with
   no qualifications, and would have been broken had there been any other kind of type sugar,
   be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
   The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
   into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
   For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.

5) It could be a bug in this patch perhaps.

Let me know if you need any help!

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Differential Revision: https://reviews.llvm.org/D112374
2022-07-27 11:10:54 +02:00

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// RUN: rm -f %t.14 %t.2a
// RUN: %clang_analyze_cc1 -analyzer-checker=debug.DumpCFG -std=c++14 -DCXX2A=0 -fblocks -Wall -Wno-unused -Werror %s > %t.14 2>&1
// RUN: %clang_analyze_cc1 -analyzer-checker=debug.DumpCFG -std=c++2a -DCXX2A=1 -fblocks -Wall -Wno-unused -Werror %s > %t.2a 2>&1
// RUN: FileCheck --input-file=%t.14 -check-prefixes=CHECK,CXX14 -implicit-check-not=destructor %s
// RUN: FileCheck --input-file=%t.2a -check-prefixes=CHECK,CXX2A -implicit-check-not=destructor %s
int puts(const char *);
struct Foo {
Foo() = delete;
#if CXX2A
// Guarantee that the elided examples are actually elided by deleting the
// copy constructor.
Foo(const Foo &) = delete;
#else
// No elision support, so we need a copy constructor.
Foo(const Foo &);
#endif
~Foo();
};
struct TwoFoos {
Foo foo1, foo2;
~TwoFoos();
};
Foo get_foo();
struct Bar {
Bar();
Bar(const Bar &);
~Bar();
Bar &operator=(const Bar &);
};
Bar get_bar();
struct TwoBars {
Bar foo1, foo2;
~TwoBars();
};
// Start of tests:
void elided_assign() {
Foo x = get_foo();
}
// CHECK: void elided_assign()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Implicit destructor)
void nonelided_assign() {
Bar x = (const Bar &)get_bar();
}
// CHECK: void nonelided_assign()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~Bar() (Implicit destructor)
void elided_paren_init() {
Foo x(get_foo());
}
// CHECK: void elided_paren_init()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Implicit destructor)
void nonelided_paren_init() {
Bar x((const Bar &)get_bar());
}
// CHECK: void nonelided_paren_init()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~Bar() (Implicit destructor)
void elided_brace_init() {
Foo x{get_foo()};
}
// CHECK: void elided_brace_init()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Implicit destructor)
void nonelided_brace_init() {
Bar x{(const Bar &)get_bar()};
}
// CHECK: void nonelided_brace_init()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~Bar() (Implicit destructor)
void elided_lambda_capture_init() {
// The copy from get_foo() into the lambda should be elided. Should call
// the lambda's destructor, but not ~Foo() separately.
// (This syntax is C++14 'generalized lambda captures'.)
auto z = [x=get_foo()]() {};
}
// CHECK: void elided_lambda_capture_init()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~(lambda at {{.*}})() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~(lambda at {{.*}})() (Implicit destructor)
void nonelided_lambda_capture_init() {
// Should call the lambda's destructor as well as ~Bar() for the temporary.
auto z = [x((const Bar &)get_bar())]() {};
}
// CHECK: void nonelided_lambda_capture_init()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CXX14: ~(lambda at {{.*}})() (Temporary object destructor)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~(lambda at {{.*}})() (Implicit destructor)
Foo elided_return_stmt_expr() {
// Two copies, both elided in C++17.
return ({ get_foo(); });
}
// CHECK: Foo elided_return_stmt_expr()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
void elided_stmt_expr() {
// One copy, elided in C++17.
({ get_foo(); });
}
// CHECK: void elided_stmt_expr()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Temporary object destructor)
void elided_stmt_expr_multiple_stmts() {
// Make sure that only the value returned out of a statement expression is
// elided.
({ get_bar(); get_foo(); });
}
// CHECK: void elided_stmt_expr_multiple_stmts()
// CHECK: ~Bar() (Temporary object destructor)
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Temporary object destructor)
void unelided_stmt_expr() {
({ (const Bar &)get_bar(); });
}
// CHECK: void unelided_stmt_expr()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~Bar() (Temporary object destructor)
void elided_aggregate_init() {
TwoFoos x{get_foo(), get_foo()};
}
// CHECK: void elided_aggregate_init()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~TwoFoos() (Implicit destructor)
void nonelided_aggregate_init() {
TwoBars x{(const Bar &)get_bar(), (const Bar &)get_bar()};
}
// CHECK: void nonelided_aggregate_init()
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: (CXXConstructExpr{{.*}}, Bar)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~Bar() (Temporary object destructor)
// CHECK: ~TwoBars() (Implicit destructor)
TwoFoos return_aggregate_init() {
return TwoFoos{get_foo(), get_foo()};
}
// CHECK: TwoFoos return_aggregate_init()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~TwoFoos() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
void lifetime_extended() {
const Foo &x = (get_foo(), get_foo());
puts("one destroyed before, one destroyed after");
}
// CHECK: void lifetime_extended()
// CHECK: ~Foo() (Temporary object destructor)
// CHECK: one destroyed before, one destroyed after
// CHECK: ~Foo() (Implicit destructor)
void not_lifetime_extended() {
Foo x = (get_foo(), get_foo());
puts("one destroyed before, one destroyed after");
}
// CHECK: void not_lifetime_extended()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CHECK: ~Foo() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: one destroyed before, one destroyed after
// CHECK: ~Foo() (Implicit destructor)
void compound_literal() {
(void)(Bar[]){{}, {}};
}
// CHECK: void compound_literal()
// CHECK: (CXXConstructExpr, Bar)
// CHECK: (CXXConstructExpr, Bar)
// CHECK: ~Bar[2]() (Temporary object destructor)
Foo elided_return() {
return get_foo();
}
// CHECK: Foo elided_return()
// CXX14: (CXXConstructExpr{{.*}}, Foo)
// CXX14: ~Foo() (Temporary object destructor)
auto elided_return_lambda() {
return [x=get_foo()]() {};
}
// CHECK: (lambda at {{.*}}) elided_return_lambda()
// CXX14: (CXXConstructExpr{{.*}}, class (lambda at {{.*}}))
// CXX14: ~(lambda at {{.*}})() (Temporary object destructor)
// CXX14: ~Foo() (Temporary object destructor)
void const_auto_obj() {
const Bar bar;
}
// CHECK: void const_auto_obj()
// CHECK: .~Bar() (Implicit destructor)
void has_default_arg(Foo foo = get_foo());
void test_default_arg() {
// FIXME: This emits a destructor but no constructor. Search CFG.cpp for
// 'PR13385' for details.
has_default_arg();
}
// CHECK: void test_default_arg()
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Temporary object destructor)
struct DefaultArgInCtor {
DefaultArgInCtor(Foo foo = get_foo());
~DefaultArgInCtor();
};
void default_ctor_with_default_arg() {
// FIXME: Default arguments are mishandled in two ways:
// - The constructor is not emitted at all (not specific to arrays; see fixme
// in CFG.cpp that mentions PR13385).
// - The destructor is emitted once, even though the default argument will be
// constructed and destructed once per array element.
// Ideally, the CFG would expand array constructions into a loop that
// constructs each array element, allowing default argument
// constructor/destructor calls to be correctly placed inside the loop.
DefaultArgInCtor qux[3];
}
// CHECK: void default_ctor_with_default_arg()
// CHECK: CXXConstructExpr, {{.*}}, DefaultArgInCtor[3]
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Temporary object destructor)
// CHECK: .~DefaultArgInCtor[3]() (Implicit destructor)
void new_default_ctor_with_default_arg(long count) {
// Same problems as above.
new DefaultArgInCtor[count];
}
// CHECK: void new_default_ctor_with_default_arg(long count)
// CHECK: CXXConstructExpr, {{.*}}, DefaultArgInCtor[]
// CXX14: ~Foo() (Temporary object destructor)
// CHECK: ~Foo() (Temporary object destructor)
#if CXX2A
// Boilerplate needed to test co_return:
namespace std {
template <typename Promise>
struct coroutine_handle {
static coroutine_handle from_address(void *) noexcept;
};
} // namespace std
struct TestPromise {
TestPromise initial_suspend();
TestPromise final_suspend() noexcept;
bool await_ready() noexcept;
void await_suspend(const std::coroutine_handle<TestPromise> &) noexcept;
void await_resume() noexcept;
Foo return_value(const Bar &);
Bar get_return_object();
void unhandled_exception();
};
namespace std {
template <typename Ret, typename... Args>
struct coroutine_traits;
template <>
struct coroutine_traits<Bar> {
using promise_type = TestPromise;
};
} // namespace std
Bar coreturn() {
co_return get_bar();
// This expands to something like:
// promise.return_value(get_bar());
// get_bar() is passed by reference to return_value() and is then destroyed;
// there is no equivalent of RVO. TestPromise::return_value also returns a
// Foo, which should be immediately destroyed.
// FIXME: The generated CFG completely ignores get_return_object().
}
// CXX2A: Bar coreturn()
// CXX2A: ~Foo() (Temporary object destructor)
// CXX2A: ~Bar() (Temporary object destructor)
#endif
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