ClangImporter’s SwiftLookupTables map Swift names to their corresponding Clang declarations. These tables are built into a module’s clang .pcm file and missing or inaccurate entries can cause name lookup to fail to find an imported declaration.
Swift has always included a helper function that would dump these tables, and swift-ide-test has a command-line switch that would invoke it, but these tools are clumsy to use in many debugging scenarios. Add a frontend flag that dumps the tables at the end of the frontend job, making it a lot easier to get at this information in the context of a specific compilation.
This patch introduces new diagnostics to the ClangImporter to help
explain why certain C, Objective-C or C++ declarations fail to import
into Swift. This patch includes new diagnostics for the following entities:
- C functions
- C struct fields
- Macros
- Objective-C properties
- Objective-C methods
In particular, notes are attached to indicate when any of the above
entities fail to import as a result of refering an incomplete (only
forward declared) type.
The new diangostics are hidden behind two new flags, -enable-experimental-clang-importer-diagnostics
and -enable-experimental-eager-clang-module-diagnostics. The first flag emits diagnostics lazily,
while the second eagerly imports all declarations visible from loaded Clang modules. The first
flag is intended for day to day swiftc use, the second for module linting or debugging the importer.
The compiler uses the non-active names to import unavailable
declarations telling the user the correct name. Right now it's still
only importing "Swift 2" and "current", but that should change.
For reference, the best example of a declaration that has four names
is a factory method with a custom NS_SWIFT_NAME annotation:
- Its raw name is the plain Objective-C name, written as a method:
'fooByFrobnicatingBar(_:)'.
- Its "Swift 2" name is the Swift-2-style translation of that to an
initializer: 'init(byFrobnicatingBar:)'
- Its "Swift 3" name applies the "omit needless words" transformation:
'init(frobnicating:)'.
- Its "Swift 4" name uses the name specified by NS_SWIFT_NAME.
* [ClangImporter] Remove importer-based NS stripping.
As Tony puts it, in the end we wound up with more Foundation
declarations imported as members or keeping "NS" than those that
dropped it, and any further decisions will be made on a case-by-case
basis. Move all of the existing cases of prefix-stripping into
Foundation's API notes and drop the logic from the compiler.
Tested by dumping the generated interface for Foundation and its
submodules for both macOS and the iOS simulator, and comparing the
results. A few cases did slip through here because of the interaction
between "SwiftName" and "Availability: nonswift".
The next commit will re-add "NS" to some stragglers that we missed.
rdar://problem/26880017
* APINotes: Add "NS" back to a few types.
NSKeyedUnarchiverDelegate
NSKeyedArchiverDelegate
NSTextCheckingTypes
NSBinarySearchingOptions
NSEnumerationOptions
NSSortOptions
More rdar://problem/26880017
* Remove now-redundant SwiftNames from API notes.
No change observed in the generated interface of Foundation and its
submodules.
Finishes rdar://problem/26880017.
Otherwise, the lookup table for "CGColor" has two entries, because of
this:
typedef struct CGColor *CGColorRef;
and that interferes with our ability to import things as members of
"CGColor" (as opposed to "CGColorRef"), which affects the fix-its we
generate when you try to use the non-member form.
This isn't necessarily the best long-term solution (as noted in the
FIXME) but it is expedient and won't break any current users.
More rdar://problem/26347297
Leftover bits of SE-0055. Now that pointer nullability is reflected
in the type system, we can properly import throwing methods with
non-object pointer return types.
Note that Swift still won't let you declare them. That's coming next.
When attempting to compile Swift 2 code (or any Swift code using the
Swift 2 names) in Swift 3, the compiler diagnostics are often entirely
useless because the names have changed radically enough that one
generally gets "no member named 'foo'" errors rather than a helpful
"'foo' was renamed to 'bar'" error. This makes for a very poor user
experience when (e.g.) trying to move Swift 2 code forward to Swift 3.
To improve the experience, when the Swift 2 and Swift 3 names of an
API differ, the Clang importer will produce a "stub" declaration that
matches the Swift 2 API. That stub will be marked with a synthesized
attribute
@available(unavailable, renamed: "the-swift-3-name")
that enables better diagnostics (e.g., "'foo' is unavailable: renamed
to 'bar') along with Fix-Its (courtesy of @jrose-apple's recent work)
that fix the Swift 2 code to compile in Swift 3.
This change addresses much of rdar://problem/25309323 (concerning QoI
of Swift 2 code compiled with a Swift 3 compiler), but some cleanup
remains.
The Swift name lookup tables and the complete Objective-C "container"
to Swift DeclContext mapping code used similar-but-different logic to
determine when to suppress a declaration (e.g., when suppressing the
accessors for a property). Centralize the logic so we get the same
behavior in both places.
When we're omitting needless words and building Swift name lookup
tables, make sure to use the proper Clang
Sema/Preprocessor/ASTContext. This still needs to be properly
detangled, but at least now we can handle omit-needless-words for
builtin Clang types (e.g., SEL) properly.
As part of this, put OmitNeedlessWords and InferDefaultArguments into
the module file extension hash for the Swift name lookup tables, since
those settings will affect the results.
When we're omitting needless words and building Swift name lookup
tables, make sure to use the proper Clang
Sema/Preprocessor/ASTContext. This still needs to be properly
detangled, but at least now we can handle omit-needless-words for
builtin Clang types (e.g., SEL) properly.
As part of this, put OmitNeedlessWords and InferDefaultArguments into
the module file extension hash for the Swift name lookup tables, since
those settings will affect the results.
Most of this is in updating the standard library, SDK overlays, and
piles of test cases to use the new names. No surprises here, although
this shows us some potential heuristic tweaks.
There is one substantive compiler change that needs to be factored out
involving synthesizing calls to copyWithZone()/copy(zone:). Aside from
that, there are four failing tests:
Swift :: ClangModules/objc_parse.swift
Swift :: Interpreter/SDK/Foundation_test.swift
Swift :: Interpreter/SDK/archiving_generic_swift_class.swift
Swift :: Interpreter/SDK/objc_currying.swift
due to two independent remaining compiler bugs:
* We're not getting partial ordering between NSCoder's
encode(AnyObject, forKey: String) and NSKeyedArchiver's version of
that method, and
* Dynamic lookup (into AnyObject) doesn't know how to find the new
names. We need the Swift name lookup tables enabled to address this.
The recently-introduced module file extensions functionality in Clang
allows us to piggy-back the Swift name lookup tables in Clang's module
files. When the Swift name lookup tables are enabled, introduce such a
module file extension, and wire it into the SwiftLookupTable.
The actual contents of the extension block are simple: a single
on-disk hash table mapping base names to "full entries", which store
the context (e.g., a class, protocol, tag, or TU) and the set of
declarations.
Allow lazy resolution of declaration IDs deserialized from the
extension block to Clang declarations, to try to minimize the set of
declarations we must deserialize. Name lookup itself is only used to
dump the Swift name lookup tables and ensure we're round-tripping
properly.
The base name -> full name mapping really isn't interesting; index
based on the base name and filter by context instead. This makes the
lookup table dumper less interesting for testing purposes
(unfortunately), but test coverage will improve greatly once we can
turn on these lookup tables.
Ensures that the Swift lookup tables get transformed name for imported
CF types, including original name (which is still
available). Otherwise, this is an NFC refactoring that gets the last
of the naming tricks into importFullName.
The translation from the Objective-C NSError** convention into Swift
throwing methods alters the names of methods. Move that computation
into importFullName. This should be NFC refactoring for everything
except the Swift name lookup tables, which will now correctly reflect
this name translation.
The getters and setters for Objective-C @property declarations are
never found by name lookup, so don't introduce them into the Swift
lookup tables. Note that we exclude some of the accessibility
declarations for unrelated reasons, as we do elsewhere in the
importer.
Refactoring that lets the Swift lookup tables get the names right for
Objective-C protocols that would conflict with another entity in the
same module (or within the bridging header). It's an NFC cleanup
everywhere else.
Start testing the construction of the Swift lookup tables in the Clang
importer for Objective-C entities. Fix some obvious issues, e.g.,
category and extension entries should be associated with the
corresponding class, and the categories/extensions shouldn't have
entries in the lookup table.
