Commit Graph

521 Commits

Author SHA1 Message Date
Anastasia Stulova a6a237f204 [OpenCL] Added addrspace_cast operator in C++ mode.
This operator is intended for casting between
pointers to objects in different address spaces
and follows similar logic as const_cast in C++.

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60193
2020-05-18 12:07:54 +01:00
Aaron Ballman 6a30894391 C++2a -> C++20 in some identifiers; NFC. 2020-04-21 15:37:19 -04:00
Erich Keane 5f0903e9be Reland Implement _ExtInt as an extended int type specifier.
I fixed the LLDB issue, so re-applying the patch.

This reverts commit a4b88c0449.
2020-04-17 10:45:48 -07:00
Sterling Augustine a4b88c0449 Revert "Implement _ExtInt as an extended int type specifier."
This reverts commit 61ba1481e2.

I'm reverting this because it breaks the lldb build with
incomplete switch coverage warnings. I would fix it forward,
but am not familiar enough with lldb to determine the correct
fix.

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:3958:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
          ^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4633:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
          ^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4889:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
2020-04-17 10:29:40 -07:00
Erich Keane 61ba1481e2 Implement _ExtInt as an extended int type specifier.
Introduction/Motivation:
LLVM-IR supports integers of non-power-of-2 bitwidth, in the iN syntax.
Integers of non-power-of-two aren't particularly interesting or useful
on most hardware, so much so that no language in Clang has been
motivated to expose it before.

However, in the case of FPGA hardware normal integer types where the
full bitwidth isn't used, is extremely wasteful and has severe
performance/space concerns.  Because of this, Intel has introduced this
functionality in the High Level Synthesis compiler[0]
under the name "Arbitrary Precision Integer" (ap_int for short). This
has been extremely useful and effective for our users, permitting them
to optimize their storage and operation space on an architecture where
both can be extremely expensive.

We are proposing upstreaming a more palatable version of this to the
community, in the form of this proposal and accompanying patch.  We are
proposing the syntax _ExtInt(N).  We intend to propose this to the WG14
committee[1], and the underscore-capital seems like the active direction
for a WG14 paper's acceptance.  An alternative that Richard Smith
suggested on the initial review was __int(N), however we believe that
is much less acceptable by WG14.  We considered _Int, however _Int is
used as an identifier in libstdc++ and there is no good way to fall
back to an identifier (since _Int(5) is indistinguishable from an
unnamed initializer of a template type named _Int).

[0]https://www.intel.com/content/www/us/en/software/programmable/quartus-prime/hls-compiler.html)
[1]http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2472.pdf

Differential Revision: https://reviews.llvm.org/D73967
2020-04-17 07:10:57 -07:00
Richard Smith 3308732300 Fix crash if base specifier parsing hits an invalid type annotation.
Also change type annotation representation from ParsedType to TypeResult
to make it clearer to consumers that they can represent invalid types.
2020-03-30 17:21:40 -07:00
Haojian Wu 6f428e09fb [AST] Fix crashes on decltype(recovery-expr).
Summary: We mark these decls as invalid.

Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77037
2020-03-30 14:56:33 +02:00
Richard Smith 499b2a8d63 PR45294: Fix handling of assumed template names looked up in the lexical
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.
2020-03-27 21:07:06 -07:00
Richard Smith 88c7ffaf94 Form invalid template-id annotations when parsing a construct that is
required to be a template-id but names an undeclared identifier.
2020-03-27 20:27:42 -07:00
Richard Smith b3f6e3d6d6 Improve recovery from invalid template-ids.
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.
2020-03-27 17:11:04 -07:00
Richard Smith 502915c619 PR45142: 'template ~X<T>' is ill-formed; reject it rather than crashing. 2020-03-23 15:07:06 -07:00
Haojian Wu 0dd0b1017c [Parser] Avoid spurious 'missing template' error in presence of typos.
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
2020-03-19 16:15:27 +01:00
Jim Lin 466f8843f5 [NFC] Remove trailing space
sed -Ei 's/[[:space:]]+$//' include/**/*.{def,h,td} lib/**/*.{cpp,h,td}
2020-02-18 10:49:13 +08:00
Saar Raz 271e495399 [Concepts] Add missing TPA commit to requires expression parsing
If an error had occurred when annotating a scope spec during the tentative parse
for a type-requirement, we would not revert nor commit the tentative parse, triggerring
an assertion failure.

Commit the TPA in this case and then do error recovery.
2020-02-12 16:26:34 +02:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Kadir Cetinkaya 42e9478e0b
[clang][CodeComplete] Support for designated initializers
Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73271
2020-01-28 16:34:15 +01:00
Saar Raz 5043962dd3 [Concepts] Fix parsing of scope specifier in compound-requirements, add more tests for scope specifiers in type-constraints
The code for parsing of type-constraints in compound-requirements was not adapted for the new TryAnnotateTypeConstraint which
caused compound-requirements with scope specifiers to ignore them.

Also add regression tests for scope specifiers in type-constraints in more contexts.
2020-01-26 20:46:53 +02:00
Richard Smith 04f131da0b DR1753: Don't permit x.NS::~T() as a pseudo-destructor name.
When used as qualified names, pseudo-destructors are always named as if
they were members of the type, never as members of the namespace
enclosing the type.
2020-01-24 18:53:50 -08:00
Saar Raz a0f50d7316 [Concepts] Requires Expressions
Implement support for C++2a requires-expressions.

Re-commit after compilation failure on some platforms due to alignment issues with PointerIntPair.

Differential Revision: https://reviews.llvm.org/D50360
2020-01-19 00:23:26 +02:00
Saar Raz baa84d8cde Revert "[Concepts] Requires Expressions"
This reverts commit 0279318997.

There have been some failing tests on some platforms, reverting while investigating.
2020-01-18 14:58:01 +02:00
Saar Raz 0279318997 [Concepts] Requires Expressions
Implement support for C++2a requires-expressions.

Differential Revision: https://reviews.llvm.org/D50360
2020-01-18 09:15:36 +02:00
Richard Smith a42fd84cff Remove redundant CXXScopeSpec from TemplateIdAnnotation.
A TemplateIdAnnotation represents only a template-id, not a
nested-name-specifier plus a template-id. Don't make a redundant copy of
the CXXScopeSpec and store it on the template-id annotation.

This slightly improves error recovery by more properly handling the case
where we would form an invalid CXXScopeSpec while parsing a typename
specifier, instead of accidentally putting the token stream into a
broken "annot_template_id with a scope specifier, but with no preceding
annot_cxxscope token" state.
2020-01-17 15:47:21 -08:00
Saar Raz ff1e0fce81 [Concepts] Type Constraints
Add support for type-constraints in template type parameters.
Also add support for template type parameters as pack expansions (where the type constraint can now contain an unexpanded parameter pack).

Differential Revision: https://reviews.llvm.org/D44352
2020-01-15 04:02:39 +02:00
Saar Raz b65b1f322b [Concepts] Function trailing requires clauses
Function trailing requires clauses now parsed, supported in overload resolution and when calling, referencing and taking the address of functions or function templates.

Differential Revision: https://reviews.llvm.org/D43357
2020-01-09 15:07:51 +02:00
Aaron Ballman 55a51e1c79 Disallow an empty string literal in an asm label
An empty string literal in an asm label does not make a whole lot of sense. GCC
does not diagnose such a construct, but it also generates code that cannot be
assembled by gas should two symbols have an empty asm label within the same TU.
This does not affect an asm statement with an empty string literal, which is
still a useful construct.
2020-01-08 08:38:02 -05:00
Ilya Biryukov f7c8ace4a5 [CodeComplete] Fix a crash in preferred type and signature help
Summary: Null type pointers could be dereferenced in some cases.

Reviewers: kadircet, sammccall

Reviewed By: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71329
2019-12-11 09:43:28 +01:00
Anastasia Stulova e6522a96f5 [OpenCL] Allow addr space qualifiers on lambda call expressions
The addr space qualifier can be added optionally for lambdas after
the attributes. They will alter the default addr space of lambda
call operator that is in generic address space by default for OpenCL.

Syntax:

[ captures ] ( params ) specifiers exception attr opencl_addrspace
                    -> ret { body }

Example:

[&] (int i) mutable __global { ... };

On the call into lambda a compatibility check will be performed to
determine whether address space of lambda object and its call operator
are compatible. This will follow regular addr space conversion rules
and there will be no difference to how addr spaces work in method
qualifiers.

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70242
2019-12-04 12:25:20 +00:00
Ilya Biryukov d9971d0b2e [clangd] Do not insert parentheses when completing a using declaration
Summary:
Would be nice to also fix this in clang, but that looks like more work
if we want to preserve signatures in informative chunks.

Fixes https://github.com/clangd/clangd/issues/118

Reviewers: kadircet

Reviewed By: kadircet

Subscribers: merge_guards_bot, MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69382
2019-10-28 09:45:10 +01:00
Richard Smith 7e8fe67f0e PR43080: Do not build context-sensitive expressions during name classification.
Summary:
We don't know what context to use until the classification result is
consumed by the parser, which could happen in a different semantic
context. So don't build the expression that results from name
classification until we get to that point and can handle it properly.

This covers everything except C++ implicit class member access, which
is a little awkward to handle properly in the face of the protected
member access check. But it at least fixes all the currently-filed
instances of PR43080.

Reviewers: efriedma

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68896

llvm-svn: 374826
2019-10-14 21:53:03 +00:00
Erich Keane 6a24e80680 [NFCI]Create CommonAttributeInfo Type as base type of *Attr and ParsedAttr.
In order to enable future improvements to our attribute diagnostics,
this moves info from ParsedAttr into CommonAttributeInfo, then makes
this type the base of the *Attr and ParsedAttr types. Quite a bit of
refactoring took place, including removing a bunch of redundant Spelling
Index propogation.

Differential Revision: https://reviews.llvm.org/D67368

llvm-svn: 371875
2019-09-13 17:39:31 +00:00
Rui Ueyama 49a3ad21d6 Fix parameter name comments using clang-tidy. NFC.
This patch applies clang-tidy's bugprone-argument-comment tool
to LLVM, clang and lld source trees. Here is how I created this
patch:

$ git clone https://github.com/llvm/llvm-project.git
$ cd llvm-project
$ mkdir build
$ cd build
$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug \
    -DLLVM_ENABLE_PROJECTS='clang;lld;clang-tools-extra' \
    -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DLLVM_ENABLE_LLD=On \
    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ../llvm
$ ninja
$ parallel clang-tidy -checks='-*,bugprone-argument-comment' \
    -config='{CheckOptions: [{key: StrictMode, value: 1}]}' -fix \
    ::: ../llvm/lib/**/*.{cpp,h} ../clang/lib/**/*.{cpp,h} ../lld/**/*.{cpp,h}

llvm-svn: 366177
2019-07-16 04:46:31 +00:00
Erik Pilkington eee944e7f9 [C++2a] Add __builtin_bit_cast, used to implement std::bit_cast
This commit adds a new builtin, __builtin_bit_cast(T, v), which performs a
bit_cast from a value v to a type T. This expression can be evaluated at
compile time under specific circumstances.

The compile time evaluation currently doesn't support bit-fields, but I'm
planning on fixing this in a follow up (some of the logic for figuring this out
is in CodeGen). I'm also planning follow-ups for supporting some more esoteric
types that the constexpr evaluator supports, as well as extending
__builtin_memcpy constexpr evaluation to use the same infrastructure.

rdar://44987528

Differential revision: https://reviews.llvm.org/D62825

llvm-svn: 364954
2019-07-02 18:28:13 +00:00
Gauthier Harnisch 796ed03b84 [C++20] add Basic consteval specifier
Summary:
this revision adds Lexing, Parsing and Basic Semantic for the consteval specifier as specified by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1073r3.html

with this patch, the consteval specifier is treated as constexpr but can only be applied to function declaration.

Changes:
 - add the consteval keyword.
 - add parsing of consteval specifier for normal declarations and lambdas expressions.
 - add the whether a declaration is constexpr is now represented by and enum everywhere except for variable because they can't be consteval.
 - adapt diagnostic about constexpr to print constexpr or consteval depending on the case.
 - add tests for basic semantic.

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: eraman, efriedma, rnkovacs, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61790

llvm-svn: 363362
2019-06-14 08:56:20 +00:00
Ilya Biryukov b1296faee0 [CodeComplete] Set preferred type for qualified-id
Reviewers: kadircet

Reviewed By: kadircet

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62514

llvm-svn: 361838
2019-05-28 15:21:03 +00:00
Richard Smith b2997f579a [c++20] P0780R2: Support pack-expansion of init-captures.
This permits an init-capture to introduce a new pack:

  template<typename ...T> auto x = [...a = T()] { /* a is a pack */ };

To support this, the mechanism for allowing ParmVarDecls to be packs has
been extended to support arbitrary local VarDecls.

llvm-svn: 361300
2019-05-21 20:10:50 +00:00
Richard Smith e958506039 Rearrange and clean up how we disambiguate lambda-introducers from ObjC
message sends, designators, and attributes.

Instead of having the tentative parsing phase sometimes return an
indicator to say what diagnostic to produce if parsing fails and
sometimes ask the caller to run it again, consistently ask the caller to
try parsing again if tentative parsing would fail or is otherwise unable
to completely parse the lambda-introducer without producing an
irreversible semantic effect.

Mostly NFC, but we should recover marginally better in some error cases
(avoiding duplicate diagnostics).

llvm-svn: 361182
2019-05-20 18:01:54 +00:00
Nicolas Lesser e47ae69fa7 Fix buildbot: Use correct Consume*() for braces.
llvm-svn: 361120
2019-05-19 15:30:00 +00:00
Nicolas Lesser f53d172710 Added a better diagnostic when using the delete operator with lambdas
Summary:
This adds a new error for missing parentheses around lambdas in delete operators.

```
int main() {
  delete []() { return new int(); }();
}
```

This will result in:

```
test.cpp:2:3: error: '[]' after delete interpreted as 'delete[]'
  delete []() { return new int(); }();
  ^~~~~~~~~
test.cpp:2:9: note: add parentheses around the lambda
  delete []() { return new int(); }();
        ^
        (                          )
```

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: riccibruno, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D36357

llvm-svn: 361119
2019-05-19 15:07:58 +00:00
Ilya Biryukov 929af67361 [Lex] Allow to consume tokens while preprocessing
Summary:
By adding a hook to consume all tokens produced by the preprocessor.
The intention of this change is to make it possible to consume the
expanded tokens without re-runnig the preprocessor with minimal changes
to the preprocessor and minimal performance penalty when preprocessing
without recording the tokens.

The added hook is very low-level and reconstructing the expanded token
stream requires more work in the client code, the actual algorithm to
collect the tokens using this hook can be found in the follow-up change.

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: eraman, nemanjai, kbarton, jsji, riccibruno, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59885

llvm-svn: 361007
2019-05-17 09:32:05 +00:00
Richard Smith b23c5e8c3d [c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose
template name is not visible to unqualified lookup.

In order to support this without a severe degradation in our ability to
diagnose typos in template names, this change significantly restructures
the way we handle template-id-shaped syntax for which lookup of the
template name finds nothing.

Instead of eagerly diagnosing an undeclared template name, we now form a
placeholder template-name representing a name that is known to not find
any templates. When the parser sees such a name, it attempts to
disambiguate whether we have a less-than comparison or a template-id.
Any diagnostics or typo-correction for the name are delayed until its
point of use.

The upshot should be a small improvement of our diagostic quality
overall: we now take more syntactic context into account when trying to
resolve an undeclared identifier on the left hand side of a '<'. In
fact, this works well enough that the backwards-compatible portion (for
an undeclared identifier rather than a lookup that finds functions but
no function templates) is enabled in all language modes.

llvm-svn: 360308
2019-05-09 03:31:27 +00:00
Richard Smith b9fb121a62 [c++20] Implement P1009R2: allow omitting the array bound in an array
new expression.

This was voted into C++20 as a defect report resolution, so we
retroactively apply it to all prior language modes (though it can never
actually be used before C++11 mode).

llvm-svn: 360006
2019-05-06 03:47:15 +00:00
Hamza Sood 8205a814a6 [c++20] Implement P0428R2 - Familiar template syntax for generic lambdas
Differential Revision: https://reviews.llvm.org/D36527

llvm-svn: 359967
2019-05-04 10:49:46 +00:00
Bruno Ricci 70ad396bc4 [Sema][NFCI] Don't allocate storage for the various CorrectionCandidateCallback unless we are going to do some typo correction
The various CorrectionCandidateCallbacks are currently heap-allocated
unconditionally. This was needed because of delayed typo correction.
However these allocations represent currently 15.4% of all allocations
(number of allocations) when parsing all of Boost (!), mostly because
of ParseCastExpression, ParseStatementOrDeclarationAfterAttrtibutes
and isCXXDeclarationSpecifier. Note that all of these callback objects
are small. Let's not do this.

Instead initially allocate the callback on the stack, and only do a
heap allocation if we are going to do some typo correction. Do this by:

1. Adding a clone function to each callback, which will do a polymorphic
   clone of the callback. This clone function is required to be implemented
   by every callback (of which there is a fair amount). Make sure this is
   the case by making it pure virtual.

2. Use this clone function when we are going to try to correct a typo.

This additionally cut the time of -fsyntax-only on all of Boost by 0.5%
(not that much, but still something). No functional changes intended.

Differential Revision: https://reviews.llvm.org/D58827

Reviewed By: rnk

llvm-svn: 356925
2019-03-25 17:08:51 +00:00
Ilya Biryukov ff2a99752f [CodeComplete] Propagate preferred type for function arguments in more cases
Summary:
See the added test for some new cases.
This change also removes special code completion calls inside the
ParseExpressionList function now that we properly propagate expected
type to the function responsible for parsing elements of the expression list
(ParseAssignmentExpression).

Reviewers: kadircet

Reviewed By: kadircet

Subscribers: xbolva00, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58541

llvm-svn: 354864
2019-02-26 11:01:50 +00:00
Anastasia Stulova 2c4730ded8 [OpenCL][PR40707] Allow OpenCL C types in C++ mode.
Allow all OpenCL types to be parsed in C++ mode.

llvm-svn: 354121
2019-02-15 12:07:57 +00:00
Ilya Biryukov 4f9543b4d6 [CodeComplete] Propagate preferred types through parser in more cases
Preferred types are used by code completion for ranking. This commit
considerably increases the number of points in code where those types
are propagated.

In order to avoid complicating signatures of Parser's methods, a
preferred type is kept as a member variable in the parser and updated
during parsing.

Differential revision: https://reviews.llvm.org/D56723

llvm-svn: 352788
2019-01-31 20:20:32 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Anastasia Stulova a9bc4bd814 Use DeclSpec for quals in DeclaratorChunk::FunctionTypeInfo.
Rather than duplicating data fields, use DeclSpec directly to store
the qualifiers for the functions/methods. This change doesn't handle
attributes yet and has to be extended further.

Differential revision: https://reviews.llvm.org/D55948

llvm-svn: 350703
2019-01-09 11:25:09 +00:00
Ilya Biryukov f1822ec431 [CodeComplete] Cleanup access checking in code completion
Summary: Also fixes a crash (see the added 'accessibility-crash.cpp' test).

Reviewers: ioeric, kadircet

Reviewed By: kadircet

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D55124

llvm-svn: 348135
2018-12-03 13:29:17 +00:00
Roman Lebedev 377748fd7b [clang][Parse] Diagnose useless null statements / empty init-statements
Summary:
clang has `-Wextra-semi` (D43162), which is not dictated by the currently selected standard.
While that is great, there is at least one more source of need-less semis - 'null statements'.
Sometimes, they are needed:
```
for(int x = 0; continueToDoWork(x); x++)
  ; // Ugly code, but the semi is needed here.
```

But sometimes they are just there for no reason:
```
switch(X) {
case 0:
  return -2345;
case 5:
  return 0;
default:
  return 42;
}; // <- oops

;;;;;;;;;;; <- OOOOPS, still not diagnosed. Clearly this is junk.
```

Additionally:
```
if(; // <- empty init-statement
   true)
  ;

switch (; // empty init-statement
        x) {
  ...
}

for (; // <- empty init-statement
     int y : S())
  ;
}

As usual, things may or may not go sideways in the presence of macros.
While evaluating this diag on my codebase of interest, it was unsurprisingly
discovered that Google Test macros are *very* prone to this.
And it seems many issues are deep within the GTest itself, not
in the snippets passed from the codebase that uses GTest.

So after some thought, i decided not do issue a diagnostic if the semi
is within *any* macro, be it either from the normal header, or system header.

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=39111 | PR39111 ]]

Reviewers: rsmith, aaron.ballman, efriedma

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D52695

llvm-svn: 347339
2018-11-20 18:59:05 +00:00