Commit Graph

3558 Commits

Author SHA1 Message Date
Simon Pilgrim 90dab1aece Remove unused param tag to fix Wdocumentation warning. NFC. 2020-08-02 15:12:01 +01:00
Joel E. Denny 9f2f3b9de6 [OpenMP] Implement TR8 `present` motion modifier in Clang (1/2)
This patch implements Clang front end support for the OpenMP TR8
`present` motion modifier for `omp target update` directives.  The
next patch in this series implements OpenMP runtime support.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84711
2020-07-29 12:18:45 -04:00
Johannes Doerfert ee05167cc4 [OpenMP] Allow traits for the OpenMP context selector `isa`
It was unclear what `isa` was supposed to mean so we did not provide any
traits for this context selector. With this patch we will allow *any*
string or identifier. We use the target attribute and target info to
determine if the trait matches. In other words, we will check if the
provided value is a target feature that is available (at the call site).

Fixes PR46338

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D83281
2020-07-29 10:22:27 -05:00
Joel E. Denny 69fc33f0cd Revert "[OpenMP] Implement TR8 `present` motion modifier in Clang (1/2)"
This reverts commit 3c3faae497.

It breaks a number of bots.
2020-07-28 20:30:05 -04:00
Joel E. Denny 3c3faae497 [OpenMP] Implement TR8 `present` motion modifier in Clang (1/2)
This patch implements Clang front end support for the OpenMP TR8
`present` motion modifier for `omp target update` directives.  The
next patch in this series implements OpenMP runtime support.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84711
2020-07-28 19:15:18 -04:00
Joel E. Denny a3d1f88fa7 [OpenMP][NFC] Consolidate `to` and `from` clause modifiers
`to` and `from` clauses take the same modifiers, which are called
"motion modifiers" in TR8, so implement handling of their modifiers
once not twice.  This will make it easier to implement additional
motion modifiers in the future.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84710
2020-07-28 19:15:18 -04:00
Richard Smith 23d6525cbd Don't form a 'context-independent expr' reference to a member during
name annotation.

Instead, defer forming the member access expression or DeclRefExpr until
we build the use of ClassifyName's result. Just build an
UnresolvedLookupExpr to track the LookupResult until we're ready to
consume it.

This also reverts commit 2f7269b677 (other
than its testcase). That change was an attempted workaround for the same
problem.
2020-07-27 19:38:22 -07:00
Joel E. Denny aa82c40f0a [OpenMP] Implement TR8 `present` map type modifier in Clang (1/2)
This patch implements Clang front end support for the OpenMP TR8
`present` map type modifier.  The next patch in this series implements
OpenMP runtime support.

This patch does not attempt to implement TR8 sec. 2.22.7.1 "map
Clause", p. 319, L14-16:

> If a map clause with a present map-type-modifier is present in a map
> clause, then the effect of the clause is ordered before all other
> map clauses that do not have the present modifier.

Compare to L10-11, which Clang does not appear to implement yet:

> For a given construct, the effect of a map clause with the to, from,
> or tofrom map-type is ordered before the effect of a map clause with
> the alloc, release, or delete map-type.

This patch also does not implement the `present` implicit-behavior for
`defaultmap` or the `present` motion-modifier for `target update`.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D83061
2020-07-22 10:15:32 -04:00
Bruno Ricci 32db24a7f2
[clang] Provide a more specific diagnostic for a misplaced lambda capture-default.
Currently a capture-default which is not the first element in the lambda-capture
is diagnosed with a generic expected variable name or 'this' in lambda capture
list, which is true but not very helpful.

If we don't have already parsed a capture-default then a lone "&" or "=" is
likely to be a misplaced capture-default, so diagnose it as such.

Differential Revision: https://reviews.llvm.org/D83681

Reviewed By: aaron.ballman
2020-07-18 20:35:16 +01:00
Haojian Wu 1d3d9c7b58 [clang] Include type specifiers in typo correction when checking isCXXDeclarationSpecifiers.
- add more tests (the test added in 2f448467e4 is weak);
- improve the `MyTemplate<type_typo, int>();` case, with this patch, typo correction
  suggests the type decl, and no regressions found.

Differential Revision: https://reviews.llvm.org/D83025
2020-07-13 12:05:09 +02:00
Atmn Patel 78443666bc [OpenMP] Add firstprivate as a default data-sharing attribute to clang
This implements the default(firstprivate) clause as defined in OpenMP
Technical Report 8 (2.22.4).

Reviewed By: jdoerfert, ABataev

Differential Revision: https://reviews.llvm.org/D75591
2020-07-12 23:01:40 -05:00
Vy Nguyen 17ea41e472 Summary: [clang] Provide a way for WhileStmt to report the location of its LParen and RParen.
Summary: This helps avoiding hacks downstream.

Reviewers: shafik

Subscribers: martong, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83529
2020-07-10 21:31:16 -04:00
cchen 2da9572a9b [OPENMP50] extend array section for stride (Parsing/Sema/AST)
Reviewers: ABataev, jdoerfert

Reviewed By: ABataev

Subscribers: yaxunl, guansong, arphaman, sstefan1, cfe-commits, sandoval, dreachem

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82800
2020-07-09 13:28:51 -05:00
Aaron Ballman d4cf4c66b5 Fix some typos (unkown -> unknown); NFC 2020-07-02 06:41:05 -04:00
Valentin Clement 2ddba3082c [flang][openmp] Use common Directive and Clause enum from llvm/Frontend
Summary:
This patch is removing the custom enumeration for OpenMP Directives and Clauses and replace them
with the newly tablegen generated one from llvm/Frontend. This is a first patch and some will follow to share the same
infrastructure where possible. The next patch should use the clauses allowance defined in the tablegen file.

Reviewers: jdoerfert, DavidTruby, sscalpone, kiranchandramohan, ichoyjx

Reviewed By: DavidTruby, ichoyjx

Subscribers: jholewinski, cfe-commits, dblaikie, MaskRay, ymandel, ichoyjx, mgorny, yaxunl, guansong, jfb, sstefan1, aaron.ballman, llvm-commits

Tags: #llvm, #flang, #clang

Differential Revision: https://reviews.llvm.org/D82906
2020-07-01 20:58:11 -04:00
lh123 83fae3f762 [CodeComplete] Add code completion after function equals
Summary:
Provide `default` and `delete` completion after the function equals.

Reviewers: kadircet, sammccall

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82548
2020-07-01 12:51:25 +08:00
Nathan James 8ba4867c27
[CodeComplete] Tweak completion for else.
If an `if` statement uses braces for its `then` block, suggest braces for the `else` and `else if` completion blocks, Otherwise don't suggest them.

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D82626
2020-06-30 16:48:24 +01:00
Richard Smith 4d1b7e9820 Fix a few cases that were incorrectly parsed as unary-expressions
instead of postfix-expressions, and improve error recovery for postfix
operators after unary-expressions.

This covers nullptr, __null, and some calls to type traits with special
parsing rules. We would previously not parse a postfix-expression suffix
for these expressions, so would reject expressions such as
__is_trivial(int)["foo"].

For the case where a postfix-expression suffix is *not* permitted after
a unary-expression (for example, after a new-expression or sizeof
expression), produce a diagnostic if one appears there anyway. That's
always ill-formed, but previously produced very bad diagnostics.
2020-06-29 14:33:21 -07:00
Melanie Blower f4aaed3bf1 Reland D81869 "Modify FPFeatures to use delta not absolute settings"
This reverts commit defd43a5b3.
with correction to solve msan report

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-27 01:34:57 -07:00
Melanie Blower defd43a5b3 Revert "Revert "Revert "Modify FPFeatures to use delta not absolute settings"""
This reverts commit 9518763d71.
Memory sanitizer fails in CGFPOptionsRAII::CGFPOptionsRAII dtor
2020-06-26 08:47:04 -07:00
Melanie Blower 9518763d71 Revert "Revert "Modify FPFeatures to use delta not absolute settings""
This reverts commit b55d723ed6.
Reapply Modify FPFeatures to use delta not absolute settings

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-26 08:00:08 -07:00
Melanie Blower b55d723ed6 Revert "Modify FPFeatures to use delta not absolute settings"
This reverts commit 3a748cbf86.
I'm reverting this commit because I forgot to format the commit message
propertly. Sorry for the thrash.
2020-06-26 07:52:57 -07:00
Melanie Blower 3a748cbf86 Modify FPFeatures to use delta not absolute settings 2020-06-26 07:41:09 -07:00
Valentin Clement 5b9ce07a76 [openmp] Use Directive_enumSize instead of OMPD_unknown position
Summary:
Previously OMPD_unknown was last item in the Directive enumeration and its position was
used in various comparison and assertion. With the new Directive enumeration, this should be
change with  llvm::omp::Directive_enumSize. This patch fix two place where it was not done in
D81736.

Reviewers: vdmitrie, jdoerfert, jdenny

Reviewed By: jdoerfert

Subscribers: yaxunl, guansong, sstefan1, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82518
2020-06-25 09:18:54 -04:00
Richard Smith d1446017f3 DR458: Search template parameter scopes in the right order.
C++ unqualified name lookup searches template parameter scopes
immediately after finishing searching the entity the parameters belong
to. (Eg, for a class template, you search the template parameter scope
after looking in that class template and its base classes and before
looking in the scope containing the class template.) This is complicated
by the fact that scope lookup within a template parameter scope looks in
a different sequence of places prior to reaching the end of the
declarator-id in the template declaration.

We used to approximate the proper lookup rule with a hack in the scope /
decl context walk inside name lookup. Now we instead compute the lookup
parent for each template parameter scope.

In order to get this right, we now make sure to enter a distinct Scope
for each template parameter scope, and make sure to re-enter the
enclosing class scopes properly when handling delay-parsed regions
within a class.
2020-06-23 17:14:33 -07:00
Richard Smith 4f5f6c1b83 Move late-parsed class member attribute handling adjacent to all the
other late-parsed class component handling.

No functionality change intended.
2020-06-23 15:43:11 -07:00
Valentin Clement d90443b1d9 [openmp] Base of tablegen generated OpenMP common declaration
Summary:
As discussed previously when landing patch for OpenMP in Flang, the idea is
to share common part of the OpenMP declaration between the different Frontend.
While doing this it was thought that moving to tablegen instead of Macros will also
give a cleaner and more powerful way of generating these declaration.
This first part of a future series of patches is setting up the base .td file for
DirectiveLanguage as well as the OpenMP version of it. The base file is meant to
be used by other directive language such as OpenACC.
In this first patch, the Directive and Clause enums are generated with tablegen
instead of the macros on OMPConstants.h. The next pacth will extend this
to other enum and move the Flang frontend to use it.

Reviewers: jdoerfert, DavidTruby, fghanim, ABataev, jdenny, hfinkel, jhuber6, kiranchandramohan, kiranktp

Reviewed By: jdoerfert, jdenny

Subscribers: arphaman, martong, cfe-commits, mgorny, yaxunl, hiraditya, guansong, jfb, sstefan1, aaron.ballman, llvm-commits

Tags: #llvm, #openmp, #clang

Differential Revision: https://reviews.llvm.org/D81736
2020-06-23 10:32:32 -04:00
Valentin Clement 8383ac6197 Revert commit 9e52530 because of dependencies issue
This reverts commit 9e525309fb.
2020-06-22 09:56:14 -04:00
Valentin Clement 9e525309fb [openmp] Base of tablegen generated OpenMP common declaration
Summary:
As discussed previously when landing patch for OpenMP in Flang, the idea is
to share common part of the OpenMP declaration between the different Frontend.
While doing this it was thought that moving to tablegen instead of Macros will also
give a cleaner and more powerful way of generating these declaration.
This first part of a future series of patches is setting up the base .td file for
DirectiveLanguage as well as the OpenMP version of it. The base file is meant to
be used by other directive language such as OpenACC.
In this first patch, the Directive and Clause enums are generated with tablegen
instead of the macros on OMPConstants.h. The next pacth will extend this
to other enum and move the Flang frontend to use it.

Reviewers: jdoerfert, DavidTruby, fghanim, ABataev, jdenny, hfinkel, jhuber6, kiranchandramohan, kiranktp

Reviewed By: jdoerfert, jdenny

Subscribers: cfe-commits, mgorny, yaxunl, hiraditya, guansong, jfb, sstefan1, aaron.ballman, llvm-commits

Tags: #llvm, #openmp, #clang

Differential Revision: https://reviews.llvm.org/D81736
2020-06-22 09:34:53 -04:00
Eric Christopher 1f593f46f3 [AST/Lex/Parse/Sema] As part of using inclusive language within
the llvm project, migrate away from the use of blacklist and whitelist.
2020-06-20 01:15:32 -07:00
Alexey Bataev 437cbad3b3 [OPENMP]Fix PR46357: Do not allow types declarations in pragmas.
Summary:
Compiler may erroneously treat current context in OpenMP pragmas as the
context where new type declaration/definition is allowed. But the
declartation/definition of the new types in OpenMP pragmas should not be
allowed.

Reviewers: jdoerfert

Subscribers: yaxunl, guansong, sstefan1, cfe-commits, caomhin

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82019
2020-06-18 13:17:03 -04:00
Haojian Wu 910689f0aa [AST] Move the "fallback to recovery expr" mechanism to CorrectDelayedTyposInExpr, NFC
Summary: Also delete two overloads, which don't seem necessary.

Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82047
2020-06-18 08:20:05 +02:00
Richard Smith 02fccc26cf Revert "DR458: Search template parameter scopes in the right order."
We weren't re-entering template scopes in the right order, causing this
to break self-host with -fdelayed-template-parsing.

This reverts commit 237c2a23b6.
2020-06-16 23:53:44 -07:00
Richard Smith 237c2a23b6 DR458: Search template parameter scopes in the right order.
C++ unqualified name lookup searches template parameter scopes
immediately after finishing searching the entity the parameters belong
to. (Eg, for a class template, you search the template parameter scope
after looking in that class template and its base classes and before
looking in the scope containing the class template.) This is complicated
by the fact that scope lookup within a template parameter scope looks in
a different sequence of places prior to reaching the end of the
declarator-id in the template declaration.

We used to approximate the proper lookup rule with a hack in the scope /
decl context walk inside name lookup. Now we instead compute the lookup
parent for each template parameter scope. This gets the right answer and
as a bonus is substantially simpler and more uniform.

In order to get this right, we now make sure to enter a distinct Scope
for each template parameter scope. (The fact that we didn't before was
already a bug, but not really observable most of the time, since
template parameters can't shadow each other.)
2020-06-16 19:41:14 -07:00
Yuanfang Chen 4676cf444e [Clang] Skip adding begin source location for PragmaLoopHint'd loop when
the range start is already set

The range start could be set already in some invalid cases. Fixes
PR46336.
2020-06-16 10:19:36 -07:00
Sam McCall 05ed3efc2a Handle delayed-template-parsing functions imported into a non-dtp TU
Summary:
DelayedTemplateParsing is marked as BENIGN_LANGOPT, so we are allowed to
use a delayed template in a non-delayed TU.
(This is clangd's default configuration on windows: delayed-template-parsing
is on for the preamble and forced off for the current file)

However today clang fails to parse implicit instantiations in a non-dtp
TU of templates defined in a dtp PCH file (and presumably module?).
In this case the delayed parser is not registered, so the function is
simply marked "delayed" again. We then hit an assert:
end of TU template instantiation should not create more late-parsed templates

Reviewers: rsmith

Subscribers: ilya-biryukov, usaxena95, cfe-commits, kadircet

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81474
2020-06-12 16:09:38 +02:00
Bruno Ricci a06f000326
[clang][NFC] Remove two hard-coded lists of ArrayTypeTrait and ExpressionTrait
These two were missed in 78e636b3f2.
2020-06-11 20:27:40 +01:00
Erich Keane 113b0d7d0b PR46255: Fix field diagnostics for C records with anonymous members.
The ParseStructUnionBody function was separately keeping track of the
field decls for historical reasons, however the "ActOn" functions add
the field to the RecordDecl anyway.

The "ParseStructDeclaration" function, which handles parsing fields
didn't have a way of handling what happens on an anonymous field, and
changing it would alter a large amount of objc code, so I chose instead
to implement this by just filling the FieldDecls vector with the actual
FieldDecls that were successfully added to the recorddecl .
2020-06-09 12:27:44 -07:00
Yuanfang Chen 9c2e770034 Add begin source location for the attributed statement created from PragmaLoopHint decorated loop
Summary:
Right now it is a '<invalid sloc>' for cases like this.
CounterCoverageMappingBuilder relies on the information to decide the
region for a attributed loop.

Fixes PR40971

Reviewers: ABataev, jdenny, lebedev.ri, aaron.ballman

Reviewed by: jdenny, aaron.ballman

Differential Revision: https://reviews.llvm.org/D80944
2020-06-09 10:08:40 -07:00
Richard Smith 56a872947a Remove improper uses of DiagnosticErrorTrap and hasErrorOccurred.
DiagnosticErrorTrap is usually inappropriate because it indicates
whether an error message was rendered in a given region (and is
therefore affected by -ferror-limit and by suppression of errors if we
see an invalid declaration).

hasErrorOccurred() is usually inappropriate because it indicates
whethere an "error:" message was displayed, regardless of whether the
message was a warning promoted to an error, and therefore depends on
things like -Werror that are usually irrelevant.

Where applicable, CodeSynthesisContexts are used to attach notes to
the first diagnostic produced in a region of code, isnstead of using an
error trap and then attaching a note to whichever diagnostic happened to
be produced last (or suppressing the note if the final diagnostic is a
disabled warning!).

This is mostly NFC.
2020-06-08 14:19:57 -07:00
Ties Stuij ecd682bbf5 [ARM] Add __bf16 as new Bfloat16 C Type
Summary:
This patch upstreams support for a new storage only bfloat16 C type.
This type is used to implement primitive support for bfloat16 data, in
line with the Bfloat16 extension of the Armv8.6-a architecture, as
detailed here:

https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a

The bfloat type, and its properties are specified in the Arm Architecture
Reference Manual:

https://developer.arm.com/docs/ddi0487/latest/arm-architecture-reference-manual-armv8-for-armv8-a-architecture-profile

In detail this patch:
- introduces an opaque, storage-only C-type __bf16, which introduces a new bfloat IR type.

This is part of a patch series, starting with command-line and Bfloat16
assembly support. The subsequent patches will upstream intrinsics
support for BFloat16, followed by Matrix Multiplication and the
remaining Virtualization features of the armv8.6-a architecture.

The following people contributed to this patch:
- Luke Cheeseman
- Momchil Velikov
- Alexandros Lamprineas
- Luke Geeson
- Simon Tatham
- Ties Stuij

Reviewers: SjoerdMeijer, rjmccall, rsmith, liutianle, RKSimon, craig.topper, jfb, LukeGeeson, fpetrogalli

Reviewed By: SjoerdMeijer

Subscribers: labrinea, majnemer, asmith, dexonsmith, kristof.beyls, arphaman, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76077
2020-06-05 10:32:43 +01:00
Alexey Bataev 2f7269b677 Fix compiler crash when an expression parsed in the tentative parsing and must be claimed in the another evaluation context.
Summary:
Clang crashes when trying to finish function body. MaybeODRUseExprs is
not empty because of const static data member parsed in outer evaluation
context, upon call for isTypeIdInParens() function. It builds
annot_primary_expr, later parsed in ParseConstantExpression() in
inner constant expression evaluation context.

Reviewers: rjmccall, rsmith

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80925
2020-06-02 14:27:33 -04:00
Alexey Bataev a888fc6b34 [OPENMP50]Initial support for use_device_addr clause.
Summary:
Added parsing/sema analysis/serialization support for use_device_addr
clauses.

Reviewers: jdoerfert

Subscribers: yaxunl, guansong, arphaman, sstefan1, llvm-commits, cfe-commits, caomhin

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D80404
2020-05-27 11:35:31 -04:00
Zola Bridges 60ee885990 [clang][asm goto][slh] Warn if asm goto + SLH
Summary:
Asm goto is not supported by SLH. Warn if an instance of asm goto is detected
while SLH is enabled.

Test included.

Reviewed By: jyu2

Differential Revision: https://reviews.llvm.org/D79743
2020-05-20 09:46:18 -07:00
Alexey Bataev 2e499eee58 [OPENMP50]Add initial support for 'affinity' clause.
Summary:
Added parsing/sema/serialization support for affinity clause in task
directives.

Reviewers: jdoerfert

Subscribers: yaxunl, guansong, arphaman, llvm-commits, cfe-commits, caomhin

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D80148
2020-05-19 08:19:09 -04:00
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
Richard Smith 8fc12b8698 Enforce the C++11 anonymous enum bitfields check even for
Objective-C++11 and under MS extensions.

This matches the MSVC behavior, and means that Objective-C behaves as a
set of extensions to the base language, rather than replacing the base
language rule with a different one.
2020-05-10 14:03:50 -07:00
Richard Smith 2d3f5a62de Fix typo in enum-base disambiguation. 2020-05-10 13:39:49 -07:00
Richard Smith d6425e2c14 Properly implement 'enum class' parsing.
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.
2020-05-10 13:21:04 -07:00
Richard Smith c90e198107 Fix parsing of enum-base to follow C++11 rules.
Previously we implemented non-standard disambiguation rules to
distinguish an enum-base from a bit-field but otherwise treated a :
after an elaborated-enum-specifier as introducing an enum-base. That
misparses various examples (anywhere an elaborated-type-specifier can
appear followed by a colon, such as within a ternary operator or
_Generic).

We now implement the C++11 rules, with the old cases accepted as
extensions where that seemed reasonable. These amount to:
 * an enum-base must always be accompanied by an enum definition (except
   in a standalone declaration of the form 'enum E : T;')
 * in a member-declaration, 'enum E :' always introduces an enum-base,
   never a bit-field
 * in a type-specifier (or similar context), 'enum E :' is not
   permitted; the colon means whatever else it would mean in that
   context.

Fixed underlying types for enums are also permitted in Objective-C and
under MS extensions, plus as a language extension in all other modes.
The behavior in ObjC and MS extensions modes is unchanged (but the
bit-field disambiguation is a bit better); remaining language modes
follow the C++11 rules.

Fixes PR45726, PR39979, PR19810, PR44941, and most of PR24297, plus C++
core issues 1514 and 1966.
2020-05-08 19:32:00 -07:00