If we deduced the arity of a pack in two different ways, but didn't
deduce an element of the pack in either of those deductions, we'd merge
that element to produce a null template argument, which we'd incorrectly
interpret as the merge having failed.
Testcase based on one supplied by Hubert Tong.
lambda when instantiating a call operator specialization.
We previously incorrectly thought that such substitution was happening
in the context of substitution into a local scope, which is a context
where we should perform eager default argument instantiation.
a default argument.
Default arguments can (after recent language changes) refer to
parameters of the same function. Make sure they're added to the local
instantiation scope before transforming a default argument so that we
can remap such references to them properly.
deduction.
Template argument deduction can trigger substitution, both with
explicitly-specified template arguments and with deduced template
arguments in various ways. We previously had no check for stack
exhaustion along some of those codepaths, making it fairly easy to crash
clang with a template resulting in a substitution that referred back to
that same template. We should now produce a proper diagnostic for such
cases rather than crashing.
outer levels as retained rather than omitting their arguments.
This better reflects what's going on (we're performing a substitution
while still inside a template), and in theory is more correct, but I've
not found a testcase where it matters in practice (largely because we
don't allow alias templates to be declared inside a function).
Fixed AST dumping of SubstNonTypeTemplateParm[Pack]Expr to demonstrate
that we're properly substituting through dependent alias templates. (We
can't deduce properly through these yet, but we can at least produce the
right input to template argument deduction.)
No functionality change intended.
templated class.
When a defaulted operator<=> results in the injection of a defaulted
operator==, that operator== can be named by unqualified name within the
same class, even if the class is templated. To make this work, perform
the transform from defaulted operator<=> to defaulted operator== in the
template definition context instead of the template instantiation
context.
This results in our substituting into a declaration from a context where
we don't have a full list of template arguments (or indeed any), for
which we are now more careful to not spuriously instantiate declarations
that are not dependent on the arguments we're substituting.
specializations and those that are done as part of rewrites.
Do not create Subst* nodes in the latter. We previously had a hybrid of
these two behaviors where we would only create some Subst* nodes but not
others during deduction guide rewrites.
No functional change intended, but the resulting ASTs are more
principled.
inner non-type pack at a different index.
We previously considered the index of the outer pack (which would refer
to an unrelated template parameter) to be deduced by deducing the inner
pack, because we inspected the (largely meaningless) type of an expanded
non-type template parameter pack.
not be a pack expansion type.
Using a pack expansion type for a pack declaration makes sense, but
general expressions should never have pack expansion types. If we have a
pack `T *...V`, then the type of `V` is the type `T *`, which contains
an unexpanded pack, and is a pointer type.
This allows us to better diagnose issues where a template is invalid due
to some non-dependent portion of a dependent type of a non-type template
parameter pack.
templated class.
When a defaulted operator<=> results in the injection of a defaulted
operator==, that operator== can be named by unqualified name within the
same class, even if the class is templated. To make this work, perform
the transform from defaulted operator<=> to defaulted operator== in the
template definition context instead of the template instantiation
context.
This results in our substituting into a declaration from a context where
we don't have a full list of template arguments (or indeed any), for
which we are now more careful to not spuriously instantiate declarations
that are not dependent on the arguments we're substituting.
redeclaration chain for an array.
A prior attempt to fix this in r280330 didn't handle the case where the
old variable is dependent and the new one is not.
It is notable and worrying that the test case in this example forms a
redeclaration chain for a non-dependent variable that includes a
declaration with a dependent type. We should probably fix that too.
Reland https://reviews.llvm.org/D76696
All known crashes have been fixed, another attemption.
We have rolled out this to all internal users for a while, didn't see
big issues, we consider it is stable enough.
Reviewed By: sammccall
Subscribers: rsmith, hubert.reinterpretcast, ebevhan, jkorous, arphaman, kadircet, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78350
...before checking that the default argument is valid with
CheckDefaultArgumentVisitor.
Currently the restrictions on a default argument are checked with the visitor
CheckDefaultArgumentVisitor in ActOnParamDefaultArgument before
performing the conversion to the parameter type in SetParamDefaultArgument.
This was fine before the previous patch but now some valid code post-CWG 2346
is rejected:
void test() {
const int i2 = 0;
extern void h2a(int x = i2); // FIXME: ok, not odr-use
extern void h2b(int x = i2 + 0); // ok, not odr-use
}
This is because the reference to i2 in h2a has not been marked yet with
NOUR_Constant. i2 is marked NOUR_Constant when the conversion to the parameter
type is done, which is done just after.
The solution is to do the conversion to the parameter type before checking
the restrictions on default arguments with CheckDefaultArgumentVisitor.
This has the side-benefit of improving some diagnostics.
Differential Revision: https://reviews.llvm.org/D81616
Reviewed By: rsmith
constraint expressions.
We create overloaded `&&` and `||` operators to hold the possible
unqualified lookup results (if any) when the operands are dependent. We
could avoid building these in some cases (we will never use the stored
lookup results, and it would be better to not store them or perform the
lookups), but in the general case we will probably still need to handle
overloaded operators even with that optimization.
We should check non-dependent element types before creating a
DependentSizedMatrixType. Otherwise we do not generate an error message
for dependent-sized matrix types with invalid non-dependent element
types, if the template is never instantiated. See the make5 struct in
the tests.
It also moves the SEMA template tests to
clang/test/SemaTemplate/matrix-type.cpp and introduces a few more test
cases.
The 'class' or 'struct' keyword is only permitted as part of either an
enum definition or a standalone opaque-enum-declaration, not as part of
an elaborated type specifier. We previously failed to diagnose this, and
generally didn't properly implement the restrictions on elaborated type
specifiers for enumeration types.
In passing, also fixed incorrect parsing for enum-bases, which we
previously parsed as a type-name, but are actually a type-specifier-seq.
This matters for cases like 'enum E : int *p;', which is valid as a
Microsoft extension.
Plus some minor parse diagnostic improvements.
Bumped the recently-added ExtWarn for 'enum E : int x;' to be
DefaultError; this is not an intentional extension, so producing an
error by default seems appropriate, but the warning flag to disable it
may still be useful for code written against old Clang. The same
treatment is given here to the diagnostic for 'enum class E x;', which
we similarly have incorrectly accepted for many years. These diagnostics
continue to be suppressed under -fms-extensions and when compiling
Objective-C code. We will need to decide separately whether Objective-C
should follow the C++ rules or the (older) MSVC rules.
Summary:
We extend the behavior for local functions and methods of local classes
to lambdas in variable initializers. The initializer is not a separate
scope, but we treat it as such.
We also remove the (faulty) instantiation of default arguments in
TreeTransform::TransformLambdaExpr, because it doesn't do proper
initialization, and if it did, we would do it twice (and thus also emit
eventual errors twice).
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D76038
constructor with default arguments.
We used to try to rebuild the call as a call to the faked-up inherited
constructor, which is only a placeholder and lacks (for example) default
arguments. Instead, build the call by reference to the original
constructor.
In passing, add a note to say where a call that recursively uses a
default argument from within itself occurs. This is usually pretty
obvious, but still at least somewhat useful, and would have saved
significant debugging time for this particular bug.
scope.
There are a few contexts in which we assume a name is a template name;
if such a context is one where we should perform an unqualified lookup,
and lookup finds nothing, we would form a dependent template name even
if the name is not dependent. This happens in particular for the lookup
of a pseudo-destructor.
In passing, rename ActOnDependentTemplateName to just ActOnTemplateName
given that we apply it for non-dependent template names too.
Instead of bailing out of parsing when we encounter an invalid
template-name or template arguments in a template-id, produce an
annotation token describing the invalid construct.
This avoids duplicate errors and generally allows us to recover better.
In principle we should be able to extend this to store some kinds of
invalid template-id in the AST for tooling use, but that isn't handled
as part of this change.
This reverts commit 0788acbccb.
This reverts commit c2d7a1f79cedfc9fcb518596aa839da4de0adb69: Revert "[clangd] Add test for FindTarget+RecoveryExpr (which already works). NFC"
It causes a crash on invalid code:
class X {
decltype(unresolved()) foo;
};
constexpr int s = sizeof(X);
Normally clang avoids creating expressions when it encounters semantic
errors, even if the parser knows which expression to produce.
This works well for the compiler. However, this is not ideal for
source-level tools that have to deal with broken code, e.g. clangd is
not able to provide navigation features even for names that compiler
knows how to resolve.
The new RecoveryExpr aims to capture the minimal set of information
useful for the tools that need to deal with incorrect code:
source range of the expression being dropped,
subexpressions of the expression.
We aim to make constructing RecoveryExprs as simple as possible to
ensure writing code to avoid dropping expressions is easy.
Producing RecoveryExprs can result in new code paths being taken in the
frontend. In particular, clang can produce some new diagnostics now and
we aim to suppress bogus ones based on Expr::containsErrors.
We deliberately produce RecoveryExprs only in the parser for now to
minimize the code affected by this patch. Producing RecoveryExprs in
Sema potentially allows to preserve more information (e.g. type of an
expression), but also results in more code being affected. E.g.
SFINAE checks will have to take presence of RecoveryExprs into account.
Initial implementation only works in C++ mode, as it relies on compiler
postponing diagnostics on dependent expressions. C and ObjC often do not
do this, so they require more work to make sure we do not produce too
many bogus diagnostics on the new expressions.
See documentation of RecoveryExpr for more details.
original patch from Ilya
This change is based on https://reviews.llvm.org/D61722
Reviewers: sammccall, rsmith
Reviewed By: sammccall, rsmith
Tags: #clang
Differential Revision: https://reviews.llvm.org/D69330
Suppress those diagnostics if lhs of a member expression contains
errors. Typo correction produces dependent expressions even in
non-template code, that led to spurious diagnostics before.
previous:
/tmp/t.cpp:6:17: error: use 'template' keyword to treat 'f' as a dependent template name
auto a = bilder.f<int>();
^
template
/tmp/t.cpp:6:10: error: use of undeclared identifier 'bilder'; did you mean 'builder'?
auto a = bilder.f<int>();
^~~~~~
builder
vs now:
/tmp/t.cpp:6:10: error: use of undeclared identifier 'bilder'; did you mean 'builder'?
auto a = bilder.f<int>();
^~~~~~
builder
Original patch from Ilya.
Reviewers: sammccall
Reviewed By: sammccall
Tags: #clang
Differential Revision: https://reviews.llvm.org/D65592
TryAnnotateTypeConstraint could annotate a template-id which doesn't end up being a type-constraint,
in which case control flow would incorrectly flow into ParseImplicitInt.
Reenter the loop in this case.
Enable relevant tests for C++20. This required disabling typo-correction during TryAnnotateTypeConstraint
and changing a test case which is broken due to a separate bug (will be reported and handled separately).
a dependent context.
This matches the GCC behavior.
We track the enclosing template depth when determining whether a
statement expression is within a dependent context; there doesn't appear
to be any other reliable way to determine this.
We previously assumed they were neither value- nor
instantiation-dependent under any circumstances, which would lead to
crashes and other misbehavior.
We would assign the incorrect DeclContext when transforming the RequiresExprBodyDecl, causing incorrect
handling of 'this' inside RequiresExprBodyDecls (bug #45162).
Assign the current context as the DeclContext of the transformed decl.
dependent constructs.
We previously assumed they were neither value- nor
instantiation-dependent under any circumstances, which would lead to
crashes and other misbehavior.
This doesn't match GCC's behavior (where statement expressions appear to
be treated as value-dependent if they appear in a dependent context),
but seems to be the best thing we can do in the short term: it turns out
to be remarkably difficult for us to correctly determine whether we are
in a dependent context (and it's not even possible in some cases, such
as in a generic lambda where we might not have seen the 'auto' yet).
This was previously reverted in 8e4a867 for rejecting some code, but that
code was invalid and Clang was previously incorrectly accepting it.
GetContainedInventedTypeParmVisitor would not account for the case where TemplateTypeParmType::getDecl() is
nullptr, causing bug #45102.
Add the nullptr check.
dependent constructs.
We previously assumed they were neither value- nor
instantiation-dependent under any circumstances, which would lead to
crashes and other misbehavior.
This doesn't match GCC's behavior (where statement expressions appear to
be treated as value-dependent if they appear in a dependent context),
but seems to be the best thing we can do in the short term: it turns out
to be remarkably difficult for us to correctly determine whether we are
in a dependent context (and it's not even possible in some cases, such
as in a generic lambda where we might not have seen the 'auto' yet).
dependent contexts.
We previously assumed they were neither value- nor
instantiation-dependent under any circumstances, which would lead to
crashes and other misbehavior.
Compute and propagate conversion kind to diagnostics helper in C++
to provide more specific diagnostics about incorrect implicit
conversions in assignments, initializations, params, etc...
Duplicated some diagnostics as errors because C++ is more strict.
Tags: #clang
Differential Revision: https://reviews.llvm.org/D74116
This patch is a follow up to 878a24ee24. Name of bitfields
with value-dependent width should be set as type-dependent. This
patch adds the required value-dependency check and sets the
type-dependency accordingly.
Patch fixes PR44886
Differential revision: https://reviews.llvm.org/D72242
Summary:
Due to a recent (but retroactive) C++ rule change, only sufficiently
C-compatible classes are permitted to be given a typedef name for
linkage purposes. Add an enabled-by-default warning for these cases, and
rephrase our existing error for the case where we encounter the typedef
name for linkage after we've already computed and used a wrong linkage
in terms of the new rule.
Reviewers: rjmccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D74103
Haojian Wu