Commit Graph

279 Commits

Author SHA1 Message Date
Richard Smith d699da427a PR37450: Fix bug that disabled some type checks for variables with deduced types.
Also improve diagnostic for the case where a type is non-literal because it's a lambda.

llvm-svn: 332286
2018-05-14 20:15:04 +00:00
Zhihao Yuan 00c9dfdfd0 P0620 follow-up: deducing `auto` from braced-init-list in new expr
Summary:
This is a side-effect brought in by p0620r0, which allows other placeholder types (derived from `auto` and `decltype(auto)`) to be usable in a `new` expression with a single-clause //braced-init-list// as its initializer (8.3.4 [expr.new]/2).  N3922 defined its semantics.

References:
 http://wg21.link/p0620r0
 http://wg21.link/n3922

Reviewers: rsmith, aaron.ballman

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D39451

llvm-svn: 320401
2017-12-11 18:29:54 +00:00
Richard Smith 263a0a33cc Don't warn about runtime behavior problems in variable initializers that we
know are going to be constant-evaluated.

Any relevant diagnostics should be produced by constant expression evaluation.

llvm-svn: 314067
2017-09-23 18:27:11 +00:00
Faisal Vali 8194a3e975 [c++2a] Implement P0409R2 - Allow lambda capture [=,this] (by hamzasood)
This patch, by hamzasood, implements P0409R2, and allows [=, this] pre-C++2a as an extension (with appropriate warnings) for consistency.

https://reviews.llvm.org/D36572

Thanks Hamza!

llvm-svn: 311224
2017-08-19 03:43:07 +00:00
Richard Smith 3291877656 [c++1z] Synthesize implicit deduction guides from constructors on demand. Rank
such guides below explicit ones, and ensure that references to the class's
template parameters are not treated as forwarding references.

We make a few tweaks to the wording in the current standard:
1) The constructor parameter list is copied faithfully to the deduction guide,
   without losing default arguments or a varargs ellipsis (which the standard
   wording loses by omission).
2) If the class template declares no constructors, we add a T() -> T<...> guide
   (which will only ever work if T has default arguments for all non-pack
   template parameters).
3) If the class template declares nothing that looks like a copy or move
   constructor, we add a T(T<...>) -> T<...> guide.
#2 and #3 follow from the "pretend we had a class type with these constructors"
philosophy for deduction guides.

llvm-svn: 295007
2017-02-14 00:25:28 +00:00
Richard Smith 60437620db [c++1z] P0091R3: Basic support for deducing class template arguments via deduction-guides.
llvm-svn: 294613
2017-02-09 19:17:44 +00:00
Malcolm Parsons 87a036259b [Sema] Add warning for unused lambda captures
Summary:
Warn when a lambda explicitly captures something that is not used in its body.

The warning is part of -Wunused and can be enabled with -Wunused-lambda-capture.

Reviewers: rsmith, arphaman, jbcoe, aaron.ballman

Subscribers: Quuxplusone, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D28467

llvm-svn: 291905
2017-01-13 15:01:06 +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
Richard Smith 16d3150852 [c++1z] When initializing a const-qualified class type, don't forget to add on
the requested cv-qualifiers after construction. This usually doesn't matter,
but it does matter within a ?: operator.

llvm-svn: 290227
2016-12-21 01:31:56 +00:00
Richard Smith 82da19ddb3 [c++1z] P0003R5: Removing dynamic exception specifications.
We continue to support dynamic exception specifications in C++1z as an
extension, but produce an error-by-default warning when we encounter one. This
allows users to opt back into the feature with a warning flag, and implicitly
opts system headers back into the feature should they happen to use it.

There is one semantic change implied by P0003R5 but not implemented here:
violating a throw() exception specification should now call std::terminate
directly instead of calling std::unexpected(), but since P0003R5 also removes
std::unexpected() and std::set_unexpected, and the default unexpected handler
calls std::terminate(), a conforming C++1z program cannot tell that we are
still calling it. The upside of this strategy is perfect backwards
compatibility; the downside is that we don't get the more efficient 'noexcept'
codegen for 'throw()'.

llvm-svn: 289019
2016-12-08 02:49:07 +00:00
Richard Smith 4baaa5ab52 DR616, and part of P0135R1: member access (or pointer-to-member access) on a
temporary produces an xvalue, not a prvalue. Support this by materializing the
temporary prior to performing the member access.

llvm-svn: 288563
2016-12-03 01:14:32 +00:00
Richard Smith ca18579766 PR23281: Fix implementation of DR1891 to implement the intent: that is, a
lambda-expression does not have a move-assignment operator.

llvm-svn: 287057
2016-11-16 00:03:24 +00:00
Eric Fiselier e4e9e281a1 [Sema] Allow static_cast<T&&>(e) to check explicit conversions for non-reference-related types.
Summary:
[expr.cast.static] states:
> 3. A glvalue of type “cv1 T1” can be cast to type “rvalue reference to cv2 T2” if “cv2 T2” is reference-compatible
> with “cv1 T1”. The result refers to the object or the specified base class subobject thereof. If T2 is
> an inaccessible or ambiguous base class of T1, a program that necessitates such a cast is
> ill-formed.
> 
> 4. Otherwise, an expression e can be explicitly converted to a type T using a static_cast of the form static_-
> cast<T>(e) if the declaration T t(e); is well-formed, for some invented temporary variable t. [...]

Currently when checking p3 Clang will diagnose `static_cast<T&&>(e)` as invalid if the argument is not reference compatible with `T`. However I believe the correct behavior is to also check p4 in those cases.  For example:

```
double y = 42;
static_cast<int&&>(y); // this should be OK.  'int&& t(y)' is well formed
```

Note that we still don't check p4 for non-reference-compatible types which are reference-related since  `T&& t(e);` should never be well formed in those cases.


Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D26231

llvm-svn: 285872
2016-11-03 02:13:17 +00:00
Richard Smith 1be59c5106 [c++1z] P0012R1: Implement a few remaining pieces: downgrade diagnostic for
mismatched dynamic exception specifications in expressions from an error to a
warning, since this is no longer ill-formed in C++1z.

Allow reference binding of a reference-to-non-noexcept function to a noexcept
function lvalue. As defect resolutions, also allow a conditional between
noexcept and non-noexcept function lvalues to produce a non-noexcept function
lvalue (rather than decaying to a function pointer), and allow function
template argument deduction to deduce a reference to non-noexcept function when
binding to a noexcept function type.

llvm-svn: 284905
2016-10-22 01:32:19 +00:00
Richard Smith 5e9746f520 DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' rules.
This has two significant effects:

1) Direct relational comparisons between null pointer constants (0 and nullopt)
   and pointers are now ill-formed. This was always the case for C, and it
   appears that C++ only ever permitted by accident. For instance, cases like
     nullptr < &a
   are now rejected.

2) Comparisons and conditional operators between differently-cv-qualified
   pointer types now work, and produce a composite type that both source
   pointer types can convert to (when possible). For instance, comparison
   between 'int **' and 'const int **' is now valid, and uses an intermediate
   type of 'const int *const *'.

Clang previously supported #2 as an extension.

We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.

This is a re-commit of r284800.

llvm-svn: 284890
2016-10-21 22:00:42 +00:00
Renato Golin 41189656ed Revert "DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' rules."
This reverts commit r284800, as it failed all ARM/AArch64 bots.

llvm-svn: 284811
2016-10-21 08:03:49 +00:00
Richard Smith 0c1c53e3fa DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' rules.
This has two significant effects:

1) Direct relational comparisons between null pointer constants (0 and nullopt)
   and pointers are now ill-formed. This was always the case for C, and it
   appears that C++ only ever permitted by accident. For instance, cases like
     nullptr < &a
   are now rejected.

2) Comparisons and conditional operators between differently-cv-qualified
   pointer types now work, and produce a composite type that both source
   pointer types can convert to (when possible). For instance, comparison
   between 'int **' and 'const int **' is now valid, and uses an intermediate
   type of 'const int *const *'.

Clang previously supported #2 as an extension.

We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.

llvm-svn: 284800
2016-10-21 02:36:37 +00:00
Richard Smith eb7ef2e1ca Re-commit r284753, reverted in r284778, with a fix for PR30749.
Original commit message:

[c++1z] Teach composite pointer type computation how to compute the composite
pointer type of two function pointers with different noexcept specifications.
While I'm here, also teach it how to merge dynamic exception specifications.

llvm-svn: 284785
2016-10-20 21:53:09 +00:00
Hans Wennborg 2b81f42a76 Revert r284753 "[c++1z] Teach composite pointer type computation how to compute the composite"
It caused PR30749.

llvm-svn: 284778
2016-10-20 20:54:32 +00:00
Richard Smith 9c37e66c31 [c++1z] Teach composite pointer type computation how to compute the composite
pointer type of two function pointers with different noexcept specifications.
While I'm here, also teach it how to merge dynamic exception specifications.

llvm-svn: 284753
2016-10-20 17:57:33 +00:00
Richard Smith 3c4f8d2e96 P0012R1: Make exception specifications be part of the type system. This
implements the bulk of the change (modifying the type system to include
exception specifications), but not all the details just yet.

llvm-svn: 284337
2016-10-16 17:54:23 +00:00
Richard Smith b2f0f05742 Re-commit r283722, reverted in r283750, with a fix for a CUDA-specific use of
past-the-end iterator.

Original commit message:

P0035R4: Semantic analysis and code generation for C++17 overaligned
allocation.

llvm-svn: 283789
2016-10-10 18:54:32 +00:00
Daniel Jasper e9abe64816 Revert "P0035R4: Semantic analysis and code generation for C++17 overaligned allocation."
This reverts commit r283722. Breaks:
  Clang.SemaCUDA.device-var-init.cu
  Clang.CodeGenCUDA.device-var-init.cu

http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-expensive/884/

llvm-svn: 283750
2016-10-10 14:13:55 +00:00
Richard Smith 189e52fcdf P0035R4: Semantic analysis and code generation for C++17 overaligned
allocation.

llvm-svn: 283722
2016-10-10 06:42:31 +00:00
Nick Lewycky 2eeddfb1ef Warn when a reference is bound to an empty l-value (dereferenced null pointer).
llvm-svn: 269572
2016-05-14 17:44:14 +00:00
Faisal Vali dc6b596ebb [Cxx1z] Implement Lambda Capture of *this by Value as [=,*this] (P0018R3)
Implement lambda capture of *this by copy.
For e.g.:
struct A {

  int d = 10;
  auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }

};

auto L = A{}.foo(); // A{}'s lifetime is gone.

// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);

If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.

Implementation Strategy:
  - amend the parser to accept *this in the lambda introducer
  - add a new king of capture LCK_StarThis
  - teach Sema::CheckCXXThisCapture to handle by copy captures of the
    enclosing object (i.e. *this)
  - when CheckCXXThisCapture does capture by copy, the corresponding 
    initializer expression for the closure's data member 
    direct-initializes it thus making a copy of '*this'.
  - in codegen, when assigning to CXXThisValue, if *this was captured by 
    copy, make sure it points to the corresponding field member, and
    not, unlike when captured by reference, what the field member points
    to.
  - mark feature as implemented in svn

Much gratitude to Richard Smith for his carefully illuminating reviews!   

llvm-svn: 263921
2016-03-21 09:25:37 +00:00
Richard Trieu dcb5557f2d Improve -Wconstant-conversion
Switch the evaluation from isIntegerConstantExpr to EvaluateAsInt.
EvaluateAsInt will evaluate more types of expressions than
isIntegerConstantExpr.

Move one case from -Wsign-conversion to -Wconstant-conversion.  The case is:
1) Source and target types are signed
2) Source type is wider than the target type
3) The source constant value is positive
4) The conversion will store the value as negative in the target.

llvm-svn: 259271
2016-01-29 23:51:16 +00:00
Richard Smith 0c6124ba82 PR17381: Treat undefined behavior during expression evaluation as an unmodeled
side-effect, so that we don't allow speculative evaluation of such expressions
during code generation.

This caused a diagnostic quality regression, so fix constant expression
diagnostics to prefer either the first "can't be constant folded" diagnostic or
the first "not a constant expression" diagnostic depending on the kind of
evaluation we're doing. This was always the intent, but didn't quite work
correctly before.

This results in certain initializers that used to be constant initializers to
no longer be; in particular, things like:

  float f = 1e100;

are no longer accepted in C. This seems appropriate, as such constructs would
lead to code being executed if sanitizers are enabled.

llvm-svn: 254574
2015-12-03 01:36:22 +00:00
Richard Smith 42b1057244 N3922: direct-list-initialization of an auto-typed variable no longer deduces a
std::initializer_list<T> type. Instead, the list must contain a single element
and the type is deduced from that.

In Clang 3.7, we warned by default on all the cases that would change meaning
due to this change. In Clang 3.8, we will support only the new rules -- per
the request in N3922, this change is applied as a Defect Report against earlier
versions of the C++ standard.

This change is not entirely trivial, because for lambda init-captures we
previously did not track the difference between direct-list-initialization and
copy-list-initialization. The difference was not previously observable, because
the two forms of initialization always did the same thing (the elements of the
initializer list were always copy-initialized regardless of the initialization
style used for the init-capture).

llvm-svn: 252688
2015-11-11 01:36:17 +00:00
David Majnemer c10b8381f7 Update tests touched by r249656
These test updates almost exclusively around the change in behavior
around enum: enums without a definition are considered incomplete except
when targeting MSVC ABIs.  Since these tests are interested in the
'incomplete-enum' behavior, restrict them to %itanium_abi_triple.

llvm-svn: 249660
2015-10-08 06:31:22 +00:00
Nick Lewycky 08426e2098 Clarify the error message when the reason the conversion is not viable is because the returned value does not match the function return type.
llvm-svn: 245979
2015-08-25 22:18:46 +00:00
Serge Pavlov 73c6a2448f Instantiate function declarations in instantiated functions.
If a function declaration is found inside a template function as in:

    template<class T> void f() {
      void g(int x = T::v) except(T::w);
    }

it must be instantiated along with the enclosing template function,
including default arguments and exception specification.

Together with the patch committed in r240974 this implements DR1484.

Differential Revision: http://reviews.llvm.org/D11194

llvm-svn: 245810
2015-08-23 10:22:28 +00:00
Davide Italiano 32cbff7809 [Sema] Be consistent about diagnostic wording: always use "cannot".
Discussed with Richard Smith.

llvm-svn: 245162
2015-08-15 15:23:14 +00:00
Adrian Prantl bc068586ac Revert "Revert r241620 and follow-up commits" and move the initialization
of the llvm targets from clang/CodeGen into ClangCheck.cpp and CIndex.cpp.

llvm-svn: 241653
2015-07-08 01:00:30 +00:00
Adrian Prantl 142ec39739 Revert r241620 and follow-up commits while investigating linux buildbot failures.
llvm-svn: 241642
2015-07-07 23:19:46 +00:00
Adrian Prantl e50371b948 Wrap clang modules and pch files in an object file container.
This patch adds ObjectFilePCHContainerOperations uses the LLVM backend
to put the contents of a PCH into a __clangast section inside a COFF, ELF,
or Mach-O object file container.

This is done to facilitate module debugging by makeing it possible to
store the debug info for the types defined by a module alongside the AST.

rdar://problem/20091852

llvm-svn: 241620
2015-07-07 20:11:29 +00:00
Davide Italiano bf0f7757e2 [Sema] Warn when shifting a negative value.
Example:
 % ./clang -Wshift-negative-value emit.c
emit.c:3:14: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
  int a = -1 << 3;
          ~~ ^
1 warning generated.

PR:		24026
Differential Revision:	 http://reviews.llvm.org/D10938
Reviewed by:	rsmith

llvm-svn: 241478
2015-07-06 18:02:09 +00:00
Richard Trieu d3967635bc Fix typo from r237482. "to reference of type" --> "to reference to type"
llvm-svn: 237507
2015-05-16 01:39:39 +00:00
Richard Trieu f956a49e6d When emitting a dropped qualifier error, show which qualifiers are dropped.
llvm-svn: 237505
2015-05-16 01:27:03 +00:00
Richard Trieu 0ff51f39de Reverse the order of types in the reference dropping qualifiers error.
The error has the form ... 'int' ... 'const int' ... dropped qualifiers.  At
first glance, it appears that the const qualifier is added.  Reverse the types
so that the second type is less qualified than the first.

llvm-svn: 237482
2015-05-15 22:07:49 +00:00
Richard Smith c38498f046 PR23334: Perform semantic checking of lambda capture initialization in the right context.
Previously we'd try to perform checks on the captures from the middle of
parsing the lambda's body, at the point where we detected that a variable
needed to be captured. This was wrong in a number of subtle ways. In
PR23334, we couldn't correctly handle the list of potential odr-uses
resulting from the capture, and our attempt to recover from that resulted
in a use-after-free.

We now defer building the initialization expression until we leave the lambda
body and return to the enclosing context, where the initialization does the
right thing. This patch only covers lambda-expressions, but we should apply
the same change to blocks and captured statements too.

llvm-svn: 235921
2015-04-27 21:27:54 +00:00
David Blaikie a953f2825b Update Clang tests to handle explicitly typed load changes in LLVM.
llvm-svn: 230795
2015-02-27 21:19:58 +00:00
Adrian Prantl cbc368c5b5 Revert "Wrap clang module files in a Mach-O, ELF, or COFF container."
llvm-svn: 230454
2015-02-25 02:44:04 +00:00
Adrian Prantl 8bf7af3de8 Wrap clang module files in a Mach-O, ELF, or COFF container.
This is a necessary prerequisite for debugging with modules.
The .pcm files become containers that hold the serialized AST which allows
us to store debug information in the module file that can be shared by all
object files that were built importing the module.

This reapplies r230044 with a fixed configure+make build and updated
dependencies and testcase requirements. Over the last iteration this
version adds
- missing target requirements for testcases that specify an x86 triple,
- a missing clangCodeGen.a dependency to libClang.a in the make build.

rdar://problem/19104245

llvm-svn: 230423
2015-02-25 01:31:45 +00:00
Richard Smith 215f423ff2 Add a warning for direct-list-initialization of a variable with a deduced type
(or of a lambda init-capture, which is sort-of such a variable). The semantics
of such constructs will change when we implement N3922, so we intend to warn on
this in Clang 3.6 then change the semantics in Clang 3.7.

llvm-svn: 228792
2015-02-11 02:41:33 +00:00
Serge Pavlov f80df57d39 Update error message text.
Previously if an enumeration was used in a nested name specifier in pre-C++11
language dialect, error message was 'XXX is not a class, namespace, or scoped
enumeration'. This patch removes the word 'scoped' as in C++11 any enumeration
may be used in this context.

llvm-svn: 226410
2015-01-18 19:05:48 +00:00
Richard Smith 5a0e50cd87 DR1048: drop top-level cv-qualifiers when deducing the return type of a
lambda-expression in C++11, to match the C++14 rules.

llvm-svn: 224620
2014-12-19 22:10:51 +00:00
Aaron Ballman 6c93b3e29c Adding a -Wunused-value warning for expressions with side effects used in an unevaluated expression context, such as sizeof(), or decltype(). Also adds a similar warning when the expression passed to typeid() *is* evaluated, since it is equally likely that the user would expect the expression operand to be unevaluated in that case.
llvm-svn: 224465
2014-12-17 21:57:17 +00:00
Richard Smith 80f57f6842 DR1891, PR21787: a lambda closure type has no default constructor, rather than
having a deleted default constructor.

llvm-svn: 223953
2014-12-10 20:04:48 +00:00
Richard Smith 410cc89374 [c++1z] Most of N4268 (allow constant evaluation for non-type template arguments).
We don't yet support pointer-to-member template arguments that have undergone
pointer-to-member conversions, mostly because we don't have a mangling for them yet.

llvm-svn: 222807
2014-11-26 03:26:53 +00:00