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
explicit functions that are not candidates.
It's not always obvious that the reason a conversion was not possible is
because the function you wanted to call is 'explicit', so explicitly say
if that's the case.
It would be nice to rank the explicit candidates higher in the
diagnostic if an implicit conversion sequence exists for their
arguments, but unfortunately we can't determine that without potentially
triggering non-immediate-context errors that we're not permitted to
produce.
(Re-submission of D39937 with fixed tests.)
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, cfe-commits
Differential Revision: https://reviews.llvm.org/D41646
llvm-svn: 321609
Summary:
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: rsmith, aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, aaron.ballman, cfe-commits
Differential Revision: https://reviews.llvm.org/D39937
llvm-svn: 321592
copy-initialization. We previously got this wrong in a couple of ways:
- we only looked for copy / move constructors and constructor templates for
this copy, and thus would fail to copy in cases where doing so should use
some other constructor (but see core issue 670),
- we mishandled the special case for disabling user-defined conversions that
blocks infinite recursion through repeated application of a copy constructor
(applying it in slightly too many cases) -- though as far as I can tell,
this does not ever actually affect the result of overload resolution, and
- we misapplied the special-case rules for constructors taking a parameter
whose type is a (reference to) the same class type by incorrectly assuming
that only happens for copy/move constructors (it also happens for
constructors instantiated from templates and those inherited from base
classes).
These changes should only affect strange corner cases (for instance, where the
copy constructor exists but has a non-const-qualified parameter type), so for
the most part it only causes us to produce more 'candidate' notes, but see the
test changes for other cases whose behavior is affected.
llvm-svn: 280776
cv-unqualified type. This is essential in order to allow move-only objects of
const-qualified types to be copy-initialized via a converting constructor.
llvm-svn: 150309
temporary object. This is blindingly obvious from reading C++
[over.match.ctor]p1, but somehow I'd missed it and it took DR152 to
educate me. Adjust one test that was relying on this non-standard
behavior.
llvm-svn: 101688
resolution. There are two sources of problems involving user-defined
conversions that this change eliminates, along with providing simpler
interfaces for checking implicit conversions:
- It eliminates a case of infinite recursion found in Boost.
- It eliminates the search for the constructor needed to copy a temporary
generated by an implicit conversion from overload
resolution. Overload resolution assumes that, if it gets a value
of the parameter's class type (or a derived class thereof), there
is a way to copy if... even if there isn't. We now model this
properly.
llvm-svn: 101680
poor (and wrong) approximation of the actual rules governing when to
build a copy and when it can be elided.
The correct implementation is actually simpler than the
approximation. When we only enumerate constructors as part of
initialization (e.g., for direct initialization or when we're copying
from a class type or one of its derived classes), we don't create a
copy. When we enumerate all conversion functions, we do create a
copy. Before, we created some extra copies and missed some
others. The new test copy-initialization.cpp shows a case where we
missed creating a (required, non-elidable) copy as part of a
user-defined conversion, which resulted in a miscompile. This commit
also fixes PR6757, where the missing copy made us reject well-formed
code in the ternary operator.
This commit also cleans up our handling of copy elision in the case
where we create an extra copy of a temporary object, which became
necessary now that we produce the right copies. The code that seeks to
find the temporary object being copied has moved into
Expr::getTemporaryObject(); it used to have two different
not-quite-the-same implementations, one in Sema and one in CodeGen.
Note that we still do not attempt to perform the named return value
optimization, so we miss copy elisions for return values and throw
expressions.
llvm-svn: 100196
therefore not creating ElaboratedTypes, which are still pretty-printed
with the written tag).
Most of these testcase changes were done by script, so don't feel too
sorry for my fingers.
llvm-svn: 98149
InitializationSequence. Specially, switch initialization of a C++
class type (either copy- or direct-initialization).
Also, make sure that we create an elidable copy-construction when
performing copy initialization of a C++ class variable. Fixes PR5826.
llvm-svn: 91750
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
semantics and improve our handling of default arguments. Specifically,
we follow this order:
- As soon as the see the '}' in the class definition, the class is
complete and we add any implicit declarations (default constructor,
copy constructor, etc.) to the class.
- If there are any default function arguments, parse them
- If there were any inline member function definitions, parse them
As part of this change, we now keep track of the the fact that we've
seen unparsed default function arguments within the AST. See the new
ParmVarDecl::hasUnparsedDefaultArg member. This allows us to properly
cope with calls inside default function arguments to other functions
where we're making use of the default arguments.
Made some C++ error messages regarding failed initializations more
specific.
llvm-svn: 61406
duplication in the handling of copy-initialization by constructor,
which occurs both for initialization of a declaration and for
overloading. The initialization code is due for some refactoring.
llvm-svn: 58756
Matheus Izvekov