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
This reverts commit 7c51f02eff because it
stills breaks the LLDB tests. This was re-landed without addressing the
issue or even agreement on how to address the issue. More details and
discussion in https://reviews.llvm.org/D112374.
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 exposed 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
This reverts commit bdc6974f92 because it
breaks all the LLDB tests that import the std module.
import-std-module/array.TestArrayFromStdModule.py
import-std-module/deque-basic.TestDequeFromStdModule.py
import-std-module/deque-dbg-info-content.TestDbgInfoContentDequeFromStdModule.py
import-std-module/forward_list.TestForwardListFromStdModule.py
import-std-module/forward_list-dbg-info-content.TestDbgInfoContentForwardListFromStdModule.py
import-std-module/list.TestListFromStdModule.py
import-std-module/list-dbg-info-content.TestDbgInfoContentListFromStdModule.py
import-std-module/queue.TestQueueFromStdModule.py
import-std-module/stack.TestStackFromStdModule.py
import-std-module/vector.TestVectorFromStdModule.py
import-std-module/vector-bool.TestVectorBoolFromStdModule.py
import-std-module/vector-dbg-info-content.TestDbgInfoContentVectorFromStdModule.py
import-std-module/vector-of-vectors.TestVectorOfVectorsFromStdModule.py
https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/45301/
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.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D112374
This changes some diagnostics to use terminology from the standard
rather than invented terminology, which improves consistency with other
diagnostics as well. There are no functional changes intended other
than wording and naming.
Summary:
This patch contains 2 separate changes:
1) the initializer of a variable should play no part in decl "invalid" bit;
2) preserve the invalid initializer via recovery exprs;
With 1), we will regress the diagnostics (one big regression is that we loose
the "selected 'begin' function with iterator type" diagnostic in for-range stmt;
but with 2) together, we don't have regressions (the new diagnostics seems to be
improved).
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78116
user interface and documentation, and update __cplusplus for C++20.
WG21 considers the C++20 standard to be finished (even though it still
has some more steps to pass through in the ISO process).
The old flag names are accepted for compatibility, as usual, and we
still have lots of references to C++2a in comments and identifiers;
those can be cleaned up separately.
initializers.
This has some interesting interactions with our existing extensions to
support C99 designated initializers as an extension in C++. Those are
resolved as follows:
* We continue to permit the full breadth of C99 designated initializers
in C++, with the exception that we disallow a partial overwrite of an
initializer with a non-trivially-destructible type. (Full overwrite
is OK, because we won't run the first initializer at all.)
* The C99 extensions are disallowed in SFINAE contexts and during
overload resolution, where they could change the meaning of valid
programs.
* C++20 disallows reordering of initializers. We only check for that for
the simple cases that the C++20 rules permit (designators of the form
'.field_name =' and continue to allow reordering in other cases).
It would be nice to improve this behavior in future.
* All C99 designated initializer extensions produce a warning by
default in C++20 mode. People are going to learn the C++ rules based
on what Clang diagnoses, so it's important we diagnose these properly
by default.
* In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and
so still diagnose C99 extensions as described above. We continue to
accept designated C++20-compatible initializers in C++ <= 17 silently
by default (but naturally still reject under -pedantic-errors).
This is not a complete implementation of P0329R4. In particular, that
paper introduces new non-C99-compatible syntax { .field { init } }, and
we do not support that yet.
This is based on a previous patch by Don Hinton, though I've made
substantial changes when addressing the above interactions.
Differential Revision: https://reviews.llvm.org/D59754
llvm-svn: 370544
destructors.
We previously tried to patch up the exception specification after
completing the class, which went wrong when the exception specification
was needed within the class body (in particular, by a friend
redeclaration of the destructor in a nested class). We now mark the
destructor as having a not-yet-computed exception specification
immediately after creating it.
This requires delaying various checks against the exception
specification (where we'd previously have just got the wrong exception
specification, and now find we have an exception specification that we
can't compute yet) when those checks fire while the class is being
defined.
This also exposed an issue that we were missing a CodeSynthesisContext
for computation of exception specifications (otherwise we'd fail to make
the module containing the definition of the class visible when computing
its members' exception specs). Adding that incidentally also gives us a
diagnostic quality improvement.
This has also exposed an pre-existing problem: making the exception
specification evaluation context a non-SFINAE context (as it should be)
results in a bootstrap failure; PR38850 filed for this.
llvm-svn: 341499
This change implements C++ DR1696, which makes initialization of a
reference member of a class from a temporary object ill-formed. The
standard wording here is imprecise, but we interpret it as meaning that
any time a mem-initializer would result in lifetime extension, the
program is ill-formed.
This reinstates r337226, reverted in r337255, with a fix for the
InitializedEntity alignment problem that was breaking ARM buildbots.
llvm-svn: 337329
This change breaks on ARM because pointers to clang::InitializedEntity are only
4 byte aligned and do not have 3 bits to store values. A possible solution
would be to change the fields in clang::InitializedEntity to enforce a bigger
alignment requirement.
The error message is
llvm/include/llvm/ADT/PointerIntPair.h:132:3: error: static_assert failed "PointerIntPair with integer size too large for pointer"
static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
include/llvm/ADT/PointerIntPair.h:73:13: note: in instantiation of template class 'llvm::PointerIntPairInfo<const clang::InitializedEntity *, 3, llvm::PointerLikeTypeTraits<const clang::InitializedEntity *> >' requested here
Value = Info::updateInt(Info::updatePointer(0, PtrVal),
llvm/include/llvm/ADT/PointerIntPair.h:51:5: note: in instantiation of member function 'llvm::PointerIntPair<const clang::InitializedEntity *, 3, (anonymous namespace)::LifetimeKind, llvm::PointerLikeTypeTraits<const clang::InitializedEntity *>, llvm::PointerIntPairInfo<const clang::InitializedEntity *, 3, llvm::PointerLikeTypeTraits<const clang::InitializedEntity *> > >::setPointerAndInt' requested here
setPointerAndInt(PtrVal, IntVal);
^
llvm/tools/clang/lib/Sema/SemaInit.cpp:6237:12: note: in instantiation of member function 'llvm::PointerIntPair<const clang::InitializedEntity *, 3, (anonymous namespace)::LifetimeKind, llvm::PointerLikeTypeTraits<const clang::InitializedEntity *>, llvm::PointerIntPairInfo<const clang::InitializedEntity *, 3, llvm::PointerLikeTypeTraits<const clang::InitializedEntity *> > >::PointerIntPair' requested here
return {Entity, LK_Extended};
Full log here:
http://lab.llvm.org:8011/builders/clang-cmake-armv7-global-isel/builds/1330http://lab.llvm.org:8011/builders/clang-cmake-armv7-full/builds/1394
llvm-svn: 337255
This change implements C++ DR1696, which makes initialization of a
reference member of a class from a temporary object ill-formed. The
standard wording here is imprecise, but we interpret it as meaning that
any time a mem-initializer would result in lifetime extension, the
program is ill-formed.
llvm-svn: 337226
Summary:
This has just bit me, so i though it would be nice to avoid that next time :)
Motivational case:
https://godbolt.org/g/cq9UNk
Basically, it's likely to happen if you don't like shadowing issues,
and use `-Wshadow` and friends. And it won't be diagnosed by clang.
The reason is, these self-assign diagnostics only work for builtin assignment
operators. Which makes sense, one could have a very special operator=,
that does something unusual in case of self-assignment,
so it may make sense to not warn on that.
But while it may be intentional in some cases, it may be a bug in other cases,
so it would be really great to have some diagnostic about it...
Reviewers: aaron.ballman, rsmith, rtrieu, nikola, rjmccall, dblaikie
Reviewed By: rjmccall
Subscribers: EricWF, lebedev.ri, thakis, Quuxplusone, cfe-commits
Differential Revision: https://reviews.llvm.org/D44883
llvm-svn: 329493
This implements something like the current direction of DR1581: we use a narrow
syntactic check to determine the set of places where a constant expression
could be evaluated, and only instantiate a constexpr function or variable if
it's referenced in one of those contexts, or is odr-used.
It's not yet clear whether this is the right set of syntactic locations; we
currently consider all contexts within templates that would result in odr-uses
after instantiation, and contexts within list-initialization (narrowing
conversions take another victim...), as requiring instantiation. We could in
principle restrict the former cases more (only const integral / reference
variable initializers, and contexts in which a constant expression is required,
perhaps). However, this is sufficient to allow us to accept libstdc++ code,
which relies on GCC's behavior (which appears to be somewhat similar to this
approach).
llvm-svn: 291318
mirror the description in the standard. Per DR1295, this means that binding a
const / rvalue reference to a bit-field no longer "binds directly", and per
P0135R1, this means that we materialize a temporary in reference binding
after adjusting cv-qualifiers and before performing a derived-to-base cast.
In C++11 onwards, this should have fixed the last case where we would
materialize a temporary of the wrong type (with a subobject adjustment inside
the MaterializeTemporaryExpr instead of outside), but we still have to deal
with that possibility in C++98, unless we want to start using xvalues to
represent materialized temporaries there too.
llvm-svn: 289250
It is possible for a field and a class to have the same name. In such
cases, performing lookup for the field might return a result set with
more than one entry. An overzealous assertion fired, causing us to
crash instead of using the non-class lookup result.
This fixes PR28060.
llvm-svn: 272247
We forgot to mark designated initializer expression that contain type
dependent array designators as type dependent. This would lead to
crashes when we try to determine which array element we were trying to
initialize.
This fixes PR22056.
llvm-svn: 225494
Specifically, when we have this situation:
struct A {
template <typename T> struct B {
int m1 = sizeof(A);
};
B<int> m2;
};
We can't parse m1's initializer eagerly because we need A to be
complete. Therefore we wait until the end of A's class scope to parse
it. However, we can trigger instantiation of B before the end of A,
which will attempt to instantiate the field decls eagerly, and it would
build a bad field decl instantiation that said it had an initializer but
actually lacked one.
Fixed by deferring instantiation of default member initializers until
they are needed during constructor analysis. This addresses a long
standing FIXME in the code.
Fixes PR19195.
Reviewed By: rsmith
Differential Revision: http://reviews.llvm.org/D5690
llvm-svn: 222192
override for the type of 'this', also clear it out (unless we're entering the
context of a lambda-expression, where it should be inherited).
llvm-svn: 199962
a defaulted special member function until the exception specification is needed
(using the same criteria used for the delayed instantiation of exception
specifications for function temploids).
EST_Delayed is now EST_Unevaluated (using 1330's terminology), and, like
EST_Uninstantiated, carries a pointer to the FunctionDecl which will be used to
resolve the exception specification.
This is enabled for all C++ modes: it's a little faster in the case where the
exception specification isn't used, allows our C++11-in-C++98 extensions to
work, and is still correct for C++98, since in that mode the computation of the
exception specification can't fail.
The diagnostics here aren't great (in particular, we should include implicit
evaluation of exception specifications for defaulted special members in the
template instantiation backtraces), but they're not much worse than before.
Our approach to the problem of cycles between in-class initializers and the
exception specification for a defaulted default constructor is modified a
little by this change -- we now reject any odr-use of a defaulted default
constructor if that constructor uses an in-class initializer and the use is in
an in-class initialzer which is declared lexically earlier. This is a closer
approximation to the current draft solution in core issue 1351, but isn't an
exact match (but the current draft wording isn't reasonable, so that's to be
expected).
llvm-svn: 160847
ctor-initializer, remember to call the Sema action to generate default
ctor-initializers. What a delightful little miscompile. Fixes PR10578
/ <rdar://problem/9877267>.
llvm-svn: 139253
struct {
typedef int A = 0;
};
According to the C++11 standard, this is not ill-formed, but does not have any ascribed meaning. We can't reasonably accept it, so treat it as ill-formed.
Also switch C++ from an incorrect 'fields can only be initialized in constructors' diagnostic for this case to C's 'illegal initializer (only variables can be initialized)'
llvm-svn: 132890
Matheus Izvekov