Commit Graph

28 Commits

Author SHA1 Message Date
Aaron Ballman 15fbae8ac3 Use "default member initializer" instead of "in-class initializer" for diagnostics.
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.
2020-09-29 15:04:23 -04:00
Haojian Wu 89d9912cbf [AST] dont invaliate VarDecl when the initializer contains errors.
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
2020-04-21 10:53:35 +02:00
Richard Smith 24ad121582 Add -std=c++20 flag, replace C++2a with C++20 throughout the Clang
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.
2020-02-18 16:16:37 -08:00
Richard Smith 5030928d60 [c++20] Implement semantic restrictions for C++20 designated
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
2019-08-30 22:52:55 +00:00
Richard Smith 2b45b267da P1286R2: Remove restriction that the exception specification of a
defaulted special member matches the implicit exception specification.

llvm-svn: 360011
2019-05-06 05:04:56 +00:00
Richard Smith 5159bbad8b PR38627: Fix handling of exception specification adjustment for
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
2018-09-05 22:30:37 +00:00
Richard Smith d87aab939a Restructure checking for, and warning on, lifetime extension.
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
2018-07-17 22:24:09 +00:00
Florian Hahn 0aa117dd2c Temporarily revert r337226 "Restructure checking for, and warning on, lifetime extension."
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/1330
http://lab.llvm.org:8011/builders/clang-cmake-armv7-full/builds/1394

llvm-svn: 337255
2018-07-17 09:23:31 +00:00
Richard Smith 0a9969b36b Restructure checking for, and warning on, lifetime extension.
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
2018-07-17 00:11:41 +00:00
Roman Lebedev 61061d69ea [Sema] Extend -Wself-assign and -Wself-assign-field to warn on overloaded self-assignment (classes)
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
2018-04-07 10:39:21 +00:00
Richard Smith 6b8e3c02ca [c++2a] P0683R1: Permit default member initializers for bit-fields.
This would be trivial, except that our in-memory and serialized representations
for FieldDecls assumed that this can't happen.

llvm-svn: 311867
2017-08-28 00:28:14 +00:00
Richard Smith d6a150829b PR23135: Don't instantiate constexpr functions referenced in unevaluated operands where possible.
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
2017-01-07 00:48:55 +00:00
Chandler Carruth cbe1eba0c6 Fix the spelling of 'bitfield' in diagnostics to be consistently 'bit-field'.
The latter agrees with most existing diagnostics and the C and C++ standards.

Differential Revision: https://reviews.llvm.org/D26530

llvm-svn: 290159
2016-12-20 02:43:58 +00:00
Richard Smith b8c0f553ed DR1295 and cleanup for P0135R1: Make our initialization code more directly
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
2016-12-09 18:49:13 +00:00
Richard Smith 8dbc6b2617 Make diagnostic for use of default member initializer before enclosing class is
complete a little more general; it is produced in other cases than the one that
it previously talked about.

llvm-svn: 287713
2016-11-22 22:55:12 +00:00
David Majnemer 76a256260e [Sema] Don't crash when a field w/ a mem-initializer clashes with a record name
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
2016-06-09 05:26:56 +00:00
David Majnemer 4f217684c7 Sema: Dependent array designators cannot be checked
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
2015-01-09 01:39:09 +00:00
Reid Kleckner d60b82f93e Handle use of default member initializers before end of outermost class
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
2014-11-17 23:36:45 +00:00
Richard Smith 7ff2bcb814 PR18560: When switching to a new context, don't just save and restore an
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
2014-01-24 01:54:52 +00:00
Eli Friedman c9817fdf16 When we're synthesizing copy/move-assignment, we can't form a reference to an
invalid field; make sure we don't try.  Fixes <rdar://problem/14084171>.

llvm-svn: 183479
2013-06-07 01:48:56 +00:00
Richard Smith 27874d603b PR14838: When a member reference is bound to a temporary, don't forget to
perform the semantic checks associated with the destruction of that temporary.
It'll be destroyed at the end of the constructor.

llvm-svn: 171818
2013-01-08 00:08:23 +00:00
Richard Smith d3b5c90865 Final piece of core issue 1330: delay computing the exception specification of
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
2012-07-27 04:22:15 +00:00
Richard Smith 45855df4c6 Recover properly if a class member declaration starts with a scope specifier
or template-id which can't be parsed.

llvm-svn: 156468
2012-05-09 08:23:23 +00:00
David Blaikie cdd91dbe9f Fix crash-on-invalid for 'operator int[]()' in C++11.
Signed off by Richard Smith.

llvm-svn: 150464
2012-02-14 09:00:46 +00:00
Richard Smith 9ca5c42582 Update all tests other than Driver/std.cpp to use -std=c++11 rather than
-std=c++0x. Patch by Ahmed Charles!

llvm-svn: 141900
2011-10-13 22:29:44 +00:00
Douglas Gregor 5ca153f112 When parsing a function-try-block that does not have a
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
2011-09-07 20:36:12 +00:00
Richard Smith 4a4beec7b0 Don't assert on initialized typedef declarations in classes:
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
2011-06-12 11:43:46 +00:00
Richard Smith 938f40b5aa Implement support for C++11 in-class initialization of non-static data members.
llvm-svn: 132878
2011-06-11 17:19:42 +00:00