Commit Graph

1793 Commits

Author SHA1 Message Date
Valeriy Savchenko 4a7afc9a88 [-Wcalled-once-parameter] Fix false positives for cleanup attr
Cleanup attribute allows users to attach a destructor-like functions
to variable declarations to be called whenever they leave the scope.
The logic of such functions is not supported by the Clang's CFG and
is too hard to be reasoned about.  In order to avoid false positives
in this situation, we assume that we didn't see ALL of the executtion
paths of the function and, thus, can warn only about multiple call
violation.

rdar://74441906

Differential Revision: https://reviews.llvm.org/D98694
2021-03-18 12:32:16 +03:00
Valeriy Savchenko f1a7d5a7b0 [-Wcalled-once-parameter] Harden analysis in terms of block use
This patch introduces a very simple inter-procedural analysis
between blocks and enclosing functions.

We always analyze blocks first (analysis is done as part of semantic
analysis that goes side-by-side with the parsing process), and at the
moment of reporting we don't know how that block will be actually
used.

This patch introduces new logic delaying reports of the "never called"
warnings on blocks.  If we are not sure that the block will be called
exactly once, we shouldn't warn our users about that.  Double calls,
however, don't require such delays.  While analyzing the enclosing
function, we can actually decide what we should do with those
warnings.

Additionally, as a side effect, we can be more confident about blocks
in such context and can treat them not as escapes, but as direct
calls.

rdar://74090107

Differential Revision: https://reviews.llvm.org/D98688
2021-03-18 12:12:18 +03:00
Valeriy Savchenko c86dacd1a4 [-Wcalled-once-parameter] Let escapes overwrite MaybeCalled states
This commit makes escapes symmetrical, meaning that having escape
before and after the branching, where parameter is not called on
one of the paths, will have the same effect.

Differential Revision: https://reviews.llvm.org/D98622
2021-03-17 11:12:55 +03:00
Valeriy Savchenko 59112eacb9 [-Wcompletion-handler] Extend list of detected conventions
Update convention detection to accomodate changes from:
https://github.com/DougGregor/swift-evolution/blob/concurrency-objc/proposals/NNNN-concurrency-objc.md#asynchronous-completion-handler-methods

Differential Revision: https://reviews.llvm.org/D98251
2021-03-10 10:43:19 +03:00
Alex Lorenz 2de0a18a89 [clang][ObjC] allow the use of NSAttributedString * return type with format_arg attribute
This is useful for APIs that want to produce an attributed NSString as a result of
some formatting API call.
2021-03-09 13:36:57 -08:00
Aaron Ballman 81bc1365d8 Correct swift_bridge duplicate attribute warning logic
The swift_bridge attribute warns when the attribute is applied multiple
times to the same declaration. However, it warns about the arguments
being different to the attribute without ever checking if the arguments
actually are different. If the arguments are different, diagnose,
otherwise silently accept the code. Either way, drop the duplicated
attribute.
2021-02-11 07:11:27 -05:00
Erik Pilkington 1e8afba6f1 [clang] Add support for attribute 'swift_async_error'
This attribute specifies how an error is represented for a swift async method.
rdar://71941280

Differential revision: https://reviews.llvm.org/D96175
2021-02-10 13:18:13 -05:00
Valeriy Savchenko 2f994d4ee9 [-Wcompletion-handler][NFC] Remove unexpected warnings on Windows 2021-02-09 13:50:11 +03:00
Valeriy Savchenko d1522d349f [-Wcompletion-handler] Support checks with builtins
It is very common to check callbacks and completion handlers for null.
This patch supports such checks using built-in functions:
  * __builtin_expect
  * __builtin_expect_with_probablity
  * __builtin_unpredictable

rdar://73455388

Differential Revision: https://reviews.llvm.org/D96268
2021-02-09 11:32:24 +03:00
Hubert Tong c6ffe4d76f [clang] Fix message text for `-Wpointer-sign` to account for plain char
The `-Wpointer-sign` warning text is inappropriate for describing the
incompatible pointer conversion between plain `char` and explicitly
`signed`/`unsigned` `char` (whichever plain `char` has the same range
as) and vice versa.

Specifically, in part, it reads "converts between pointers to integer
types with different sign". This patch changes that portion to read
instead as "converts between pointers to integer types where one is of
the unique plain 'char' type and the other is not" when one of the types
is plain `char`.

C17 subclause 6.5.16.1 indicates that the conversions resulting in
`-Wpointer-sign` warnings in assignment-like contexts are constraint
violations. This means that strict conformance requires a diagnostic for
the case where the message text is wrong before this patch. The lack of
an even more specialized warning group is consistent with GCC.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D93999
2021-01-11 18:41:14 -05:00
Valeriy Savchenko fec1a442e3 [-Wcalled-once-parameter] Introduce 'called_once' attribute
This commit introduces a new attribute `called_once`.
It can be applied to function-like parameters to signify that
this parameter should be called exactly once.  This concept
is particularly widespread in asynchronous programs.

Additionally, this commit introduce a new group of dataflow
analysis-based warnings to check this property.  It identifies
and reports the following situations:
  * parameter is called twice
  * parameter is never called
  * parameter is not called on one of the paths

Current implementation can also automatically infer `called_once`
attribute for completion handler paramaters that should follow the
same principle by convention.  This behavior is OFF by default and
can be turned on by using `-Wcompletion-handler`.

Differential Revision: https://reviews.llvm.org/D92039

rdar://72812043
2021-01-05 18:26:44 +03:00
Fangrui Song 6b3351792c [test] Add {{.*}} to make tests immune to dso_local/dso_preemptable/(none) differences
For a definition (of most linkage types), dso_local is set for ELF -fno-pic/-fpie
and COFF, but not for Mach-O.  This nuance causes unneeded binary format differences.

This patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `
if there is an explicit linkage.

* Clang will set dso_local for Mach-O, which is currently implied by TargetMachine.cpp. This will make COFF/Mach-O and executable ELF similar.
* Eventually I hope we can make dso_local the textual LLVM IR default (write explicit "dso_preemptable" when applicable) and -fpic ELF will be similar to everything else. This patch helps move toward that goal.
2020-12-30 20:52:01 -08:00
Tomas Matheson f500662924 Detect section type conflicts between functions and variables
If two variables are declared with __attribute__((section(name))) and
the implicit section types (e.g. read only vs writeable) conflict, an
error is raised. Extend this mechanism so that an error is raised if the
section type implied by a function's __attribute__((section)) conflicts
with that of another variable.
2020-12-17 11:43:47 -05:00
Erik Pilkington 95b2dab199 [Sema] Fix a miscompile by retaining array qualifiers when folding VLAs to constant arrays
rdar://72243125

Differential revision: https://reviews.llvm.org/D93247
2020-12-16 10:01:24 -05:00
Erik Pilkington 5a28e1d9e5 [clang] Add support for attribute 'swift_async'
This attributes specifies how (or if) a given function or method will be
imported into a swift async method. rdar://70111252

Differential revision: https://reviews.llvm.org/D92742
2020-12-07 17:19:26 -05:00
Erik Pilkington 9cd2413f1c [clang] Add a new nullability annotation for swift async: _Nullable_result
_Nullable_result generally like _Nullable, except when being imported into a
swift async method. rdar://70106409

Differential revision: https://reviews.llvm.org/D92495
2020-12-07 17:19:20 -05:00
Alex Lorenz db226cdf4c [objc] diagnose protocol conformance in categories with direct members
in their corresponding class interfaces

Categories that add protocol conformances to classes with direct members should prohibit protocol
conformances when the methods/properties that the protocol expects are actually declared as 'direct' in the class.

Differential Revision: https://reviews.llvm.org/D92602
2020-12-04 15:55:34 -08:00
Alex Lorenz eddd1d192b [clang] add a `swift_async_name` attribute
The swift_async_name attribute provides a name for a function/method that can be used
to call the async overload of this method from Swift. This name specified in this attribute
assumes that the last parameter in the function/method its applied to is removed when
Swift invokes it, as the the Swift's await/async transformation implicitly constructs the callback.

Differential Revision: https://reviews.llvm.org/D92355
2020-12-04 15:55:29 -08:00
Alex Lorenz 03dcd57ecf [clang] add a new `swift_attr` attribute
The swift_attr attribute is a generic annotation attribute that's not used by clang,
but is used by the Swift compiler. The Swift compiler can use these annotations to provide
various syntactic and semantic sugars for the imported Objective-C API declarations.

Differential Revision: https://reviews.llvm.org/D92354
2020-12-04 15:53:24 -08:00
Erik Pilkington 090dd647d9 [Sema] Fold VLAs to constant arrays in a few more contexts
552c6c2 removed support for promoting VLAs to constant arrays when the bounds
isn't an ICE, since this can result in miscompiling a conforming program that
assumes that the array is a VLA. Promoting VLAs for fields is still supported,
since clang doesn't support VLAs in fields, so no conforming program could have
a field VLA.

This change is really disruptive, so this commit carves out two more cases
where we promote VLAs which can't miscompile a conforming program:

 - When the VLA appears in an ivar -- this seems like a corollary to the field thing
 - When the VLA has an initializer -- VLAs can't have an initializer

Differential revision: https://reviews.llvm.org/D90871
2020-12-04 10:03:23 -05:00
Aaron Puchert dea31f135c Consistent spelling in diagnostics: {l,r}value instead of {l,r}-value
As Richard Smith pointed out in the review of D90123, both the C and C++
standard call it lvalue and rvalue, so let's stick to the same spelling
in Clang.
2020-11-15 18:05:11 +01:00
Richard Smith 552c6c2328 PR44406: Follow behavior of array bound constant folding in more recent versions of GCC.
Old GCC used to aggressively fold VLAs to constant-bound arrays at block
scope in GNU mode. That's non-conforming, and more modern versions of
GCC only do this at file scope. Update Clang to do the same.

Also promote the warning for this from off-by-default to on-by-default
in all cases; more recent versions of GCC likewise warn on this by
default.

This is still slightly more permissive than GCC, as pointed out in
PR44406, as we still fold VLAs to constant arrays in structs, but that
seems justifiable given that we don't support VLA-in-struct (and don't
intend to ever support it), but GCC does.

Differential Revision: https://reviews.llvm.org/D89523
2020-10-16 14:34:35 -07:00
Saleem Abdulrasool 58cdbf518b Sema: add support for `__attribute__((__swift_private__))`
This attribute allows declarations to be restricted to the framework
itself, enabling Swift to remove the declarations when importing
libraries.  This is useful in the case that the functions can be
implemented in a more natural way for Swift.

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87720
Reviewed By: Aaron Ballman
2020-09-25 22:33:53 +00:00
Saleem Abdulrasool 296d8832a3 Sema: add support for `__attribute__((__swift_newtype__))`
Add the `swift_newtype` attribute which allows a type definition to be
imported into Swift as a new type.  The imported type must be either an
enumerated type (enum) or an object type (struct).

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87652
Reviewed By: Aaron Ballman
2020-09-24 15:17:35 +00:00
Saleem Abdulrasool 9bb5ecf1f7 Sema: introduce `__attribute__((__swift_name__))`
This introduces the new `swift_name` attribute that allows annotating
APIs with an alternate spelling for Swift.  This is used as part of the
importing mechanism to allow interfaces to be imported with a new name
into Swift.  It takes a parameter which is the Swift function name.
This parameter is validated to check if it matches the possible
transformed signature in Swift.

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87534
Reviewed By: Aaron Ballman, Dmitri Gribenko
2020-09-22 15:32:23 +00:00
Saleem Abdulrasool 77a01d9498 Sema: add support for `__attribute__((__swift_bridge__))`
This extends semantic analysis of attributes for Swift interoperability
by introducing the `swift_bridge` attribute.  This attribute enables
bridging Objective-C types to Swift specific types.

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87532
Reviewed By: Aaron Ballman
2020-09-16 17:54:57 +00:00
Saleem Abdulrasool 7d26d6a1b0 Sema: add support for `__attribute__((__swift_bridged_typedef__))`
Extend the semantic attributes that clang processes for Swift to include
`swift_bridged_typedef`.  This attribute enables typedefs to be bridged
into Swift with a bridged name.

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87396
Reviewed By: Aaron Ballman
2020-09-15 20:15:34 +00:00
Saleem Abdulrasool 916b434035 Sema: add support for `__attribute__((__swift_objc_members__))`
This adds the `__swift_objc_members__` attribute to the semantic
analysis.  It allows for annotating ObjC interfaces to provide Swift
semantics indicating that the types derived from this interface will be
back-bridged to Objective-C to allow interoperability with Objective-C
and Swift.

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87395
Reviewed By: Aaron Ballman, Dmitri Gribenko
2020-09-14 15:24:41 +00:00
Saleem Abdulrasool f5ab5b20fb Sema: add support for `__attribute__((__swift_error__))`
Introduce a new attribute that is used to indicate the error handling
convention used by a function.  This is used to translate the error
semantics from the decorated interface to a compatible Swift interface.

The supported error convention is one of:
- none: no error handling
- nonnull_error: a non-null error parameter indicates an error signifier
- null_result: a return value of NULL is an error signifier
- zero_result: a return value of 0 is an error signifier
- nonzero_result: a non-zero return value is an error signifier

Since this is the first of the attributes needed to support the semantic
annotation for Swift, this change also includes the necessary supporting
infrastructure for a new category of attributes (Swift).

This is based on the work of the original changes in
8afaf3aad2

Differential Revision: https://reviews.llvm.org/D87331
Reviewed By: John McCall, Aaron Ballman, Dmitri Gribenko
2020-09-11 21:20:38 +00:00
Erik Pilkington 0f1be87e29 [Sema] Fix a -Warc-repeated-use-of-weak false-positive by only calling CheckPlaceholderExpr once
Previously, this code discarded the result of CheckPlaceholderExpr for
non-matrix subexpressions. Not only is this wasteful, but it was creating a
Warc-repeated-use-of-weak false-positive on the attached testcase, since the
discarded expression was still registered as a use of the weak property.

rdar://66162246

Differential revision: https://reviews.llvm.org/D87102
2020-09-03 16:56:35 -04:00
Richard Smith 6f33936719 Explain why the array bound is non-constant in VLA diagnostics.
In passing, also use a more precise diagnostic to explain why an
expression is not an ICE if it's not of integral type.
2020-08-19 15:45:51 -07:00
Bruno Ricci acf3bdc283
[clang][NFC] Tests showing the problems with some uses of NamedDecl::getDeclName in diagnostics, SemaOverload.cpp+SemaStmt.cpp part 2020-07-18 20:44:06 +01:00
Erik Pilkington 2f71cf6d77 [SemaObjC] Fix a -Wobjc-signed-char-bool false-positive with binary conditional operator
We were previously bypassing the conditional expression special case for binary
conditional expressions.

rdar://64134411

Differential revision: https://reviews.llvm.org/D81751
2020-07-07 13:29:54 -04:00
Erik Pilkington 7437a94965 [SemaObjC] Add a warning for @selector expressions that potentially refer to objc_direct methods
By default, only warn when the selector matches a direct method in the current
class. This commit also adds a more strict off-by-default warning when there
isn't a non-direct method in the current class.

rdar://64621668

Differential revision: https://reviews.llvm.org/D82611
2020-07-07 13:29:54 -04:00
Cullen Rhodes 1ef75f53e9 [AArch64][SVE] clang: Add missing svbfloat16_t tests
Summary:
Patch adds tests for mangling of svbfloat16_t and several other type
related tests.

Reviewers: sdesmalen, kmclaughlin, fpetrogalli, efriedma

Reviewed By: sdesmalen, fpetrogalli

Differential Revision: https://reviews.llvm.org/D82668
2020-06-29 16:48:53 +00:00
Florian Hahn 043b608399 [Matrix] Use 1st/2nd instead of first/second in matrix diags.
This was suggested in D72782 and brings the diagnostics more in line
with how argument references are handled elsewhere.

Reviewers: rjmccall, jfb, Bigcheese

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D82473
2020-06-25 11:55:03 +01:00
Florian Hahn eb4c758fe4 [Matrix] Pass darwin tripe to SeamObjc test to fix windows bot failure.
Without the triple, the test fails on a windows bot
(http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/16531/steps/stage%201%20check/logs/stdio)

because of different full type widths (unsigned long long vs unsigned long)
2020-06-18 13:35:03 +01:00
Hans Wennborg d8c612b7ea Make matrix-type-builtins.m pass also on platforms where the type is 'unsigned long long' 2020-06-18 14:06:55 +02:00
Florian Hahn b5e082e728 [Matrix] Add __builtin_matrix_column_store to Clang.
This patch add __builtin_matrix_column_major_store to Clang,
as described in clang/docs/MatrixTypes.rst. In the initial version,
the stride is not optional yet.

Reviewers: rjmccall, jfb, rsmith, Bigcheese

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D72782
2020-06-18 11:39:02 +01:00
Florian Hahn 3323a628ec [Matrix] Add __builtin_matrix_transpose to Clang.
This patch add __builtin_matrix_transpose to Clang, as described in
clang/docs/MatrixTypes.rst.

Reviewers: rjmccall, jfb, rsmith, Bigcheese

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D72778
2020-06-09 10:14:37 +01:00
Florian Hahn 8f3f88d2f5 [Matrix] Implement matrix index expressions ([][]).
This patch implements matrix index expressions
(matrix[RowIdx][ColumnIdx]).

It does so by introducing a new MatrixSubscriptExpr(Base, RowIdx, ColumnIdx).
MatrixSubscriptExprs are built in 2 steps in ActOnMatrixSubscriptExpr. First,
if the base of a subscript is of matrix type, we create a incomplete
MatrixSubscriptExpr(base, idx, nullptr). Second, if the base is an incomplete
MatrixSubscriptExpr, we create a complete
MatrixSubscriptExpr(base->getBase(), base->getRowIdx(), idx)

Similar to vector elements, it is not possible to take the address of
a MatrixSubscriptExpr.
For CodeGen, a new MatrixElt type is added to LValue, which is very
similar to VectorElt. The only difference is that we may need to cast
the type of the base from an array to a vector type when accessing it.

Reviewers: rjmccall, anemet, Bigcheese, rsmith, martong

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D76791
2020-06-01 20:08:49 +01:00
Volodymyr Sapsai 6a3469f58d [ObjC] Add compatibility mode for type checking of qualified id block parameters.
Commit 73152a2ec2 fixed type checking for
blocks with qualified id parameters. But there are existing APIs in
Apple SDKs relying on the old type checking behavior. Specifically,
these are APIs using NSItemProviderCompletionHandler in
Foundation/NSItemProvider.h. To keep existing code working and to allow
developers to use affected APIs introduce a compatibility mode that
enables the previous and the fixed type checking. This mode is enabled
only on Darwin platforms.

Reviewed By: jyknight, ahatanak

Differential Revision: https://reviews.llvm.org/D79511
2020-05-14 12:08:19 -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
Erik Pilkington 873e279095 [SemaObjC] Add a warning for dictionary literals with duplicate keys
Duplicate keys in a literal break NSDictionary's invariants. rdar://50454461A

Differential revision: https://reviews.llvm.org/D78660
2020-05-05 15:30:39 -04:00
Volodymyr Sapsai 65f58878e7 [ObjC generics] Fix not inheriting type bounds in categories/extensions.
When a category/extension doesn't repeat a type bound, corresponding
type parameter is substituted with `id` when used as a type argument. As
a result, in the added test case it was causing errors like

> type argument 'T' (aka 'id') does not satisfy the bound ('id<NSCopying>') of type parameter 'T'

We are already checking that type parameters should be consistent
everywhere (see `checkTypeParamListConsistency`) and update
`ObjCTypeParamDecl` to have correct underlying type. And when we use the
type parameter as a method return type or a method parameter type, it is
substituted to the bounded type. But when we use the type parameter as a
type argument, we check `ObjCTypeParamType` that wasn't updated and
remains `id`.

Fix by updating not only `ObjCTypeParamDecl` UnderlyingType but also
TypeForDecl as we use the underlying type to create a canonical type for
`ObjCTypeParamType` (see `ASTContext::getObjCTypeParamType`).

This is a different approach to fixing the issue. The previous one was
02c2ab3d88 which was reverted in
4c539e8da1. The problem with the previous
approach was that `ObjCTypeParamType::desugar` was returning underlying
type for `ObjCTypeParamDecl` without applying any protocols stored in
`ObjCTypeParamType`. It caused inconsistencies in comparing types before
and after desugaring.

Re-applying after fixing intermittent test failures.

rdar://problem/54329242

Reviewed By: erik.pilkington

Differential Revision: https://reviews.llvm.org/D72872
2020-04-24 16:32:28 -07:00
Erik Pilkington 85cca945b4 [SemaObjC] Forbid storing an unboxed integer literal in an NSNumber
This fixes a common mistake (the 3 should be @3): NSNumber *n = 3. This extends
an existing check for NSString. Also, this only errs if the initializer isn't a
null pointer constant, so NSNumber *n = 0; continues to work. rdar://47029572

Differential revision: https://reviews.llvm.org/D78066
2020-04-20 15:22:51 -04:00
Volodymyr Sapsai 8fb7cfcea9 Revert "[ObjC generics] Fix not inheriting type bounds in categories/extensions."
This reverts commit a8c8b627f2. It causes
intermittent

    Clang :: SemaObjC/parameterized_classes_subst.m

test failures on various bots.
2020-04-07 17:41:30 -07:00
Volodymyr Sapsai a8c8b627f2 [ObjC generics] Fix not inheriting type bounds in categories/extensions.
When a category/extension doesn't repeat a type bound, corresponding
type parameter is substituted with `id` when used as a type argument. As
a result, in the added test case it was causing errors like

> type argument 'T' (aka 'id') does not satisfy the bound ('id<NSCopying>') of type parameter 'T'

We are already checking that type parameters should be consistent
everywhere (see `checkTypeParamListConsistency`) and update
`ObjCTypeParamDecl` to have correct underlying type. And when we use the
type parameter as a method return type or a method parameter type, it is
substituted to the bounded type. But when we use the type parameter as a
type argument, we check `ObjCTypeParamType` that wasn't updated and
remains `id`.

Fix by updating not only `ObjCTypeParamDecl` UnderlyingType but also
TypeForDecl as we use the underlying type to create a canonical type for
`ObjCTypeParamType` (see `ASTContext::getObjCTypeParamType`).

This is a different approach to fixing the issue. The previous one was
02c2ab3d88 which was reverted in
4c539e8da1. The problem with the previous
approach was that `ObjCTypeParamType::desugar` was returning underlying
type for `ObjCTypeParamDecl` without applying any protocols stored in
`ObjCTypeParamType`. It caused inconsistencies in comparing types before
and after desugaring.

rdar://problem/54329242

Reviewed By: erik.pilkington

Differential Revision: https://reviews.llvm.org/D72872
2020-04-03 16:29:02 -07:00
Richard Smith 0c42539df3 Improve error recovery from missing '>' in template argument list.
Produce the conventional "to match this '<'" note, so that the user
knows why we expected a '>', and properly handle '>>' in C++11 onwards.
2020-03-27 18:59:01 -07:00