Until now, only ">=" was supported in #if swift() expressions, for example:
```#if swift(>=2.1)
```#endif
This means that if we want to evaluate code only when the language version is
less than a particular version we need to do the following:
```#if !swift(>=2.1)
```#endif
An alernative to make this more readable (the "!" can be easily missed in a code
review) is to introduce another supported unary operator, "<". The previous
example could be rewritten like this:
```#if swift(<2.1)
```#endif
This commit adds support for that unary operator, along with some tests.
This was removed upstream in https://reviews.llvm.org/D47789 since the only
place this flag was used was in the windows implementation where the behavior
triggered by this could be hidden in the implementation instead of being an
argument. As such, this code doesn't compile on master-next.
Since this has an acceptable default argument given the current stable, we can
just fix this on master and everything will work.
rdar://42862352
This replaces the use of a Clang utility function that was
inexplicably a non-static member function of CompilerInstance. It
would be nice to sink this all the way to LLVM and share the
implementation across both projects, but the Clang implementation does
a handful of things we don't need, and it's hard to justify including
them in an LLVM-level interface. (I stared at
llvm/Support/FileSystem.h for a long time before giving up.)
Anyway, Serialization and FrontendTool both get their atomic writes
now without depending on Clang, and without duplicating the
scaffolding around the Clang API. We should probably adopt this for
all our output files.
No functionality change.
One use case is using DenseSet to manage a set of source locations, so that we
emit at most one compiler diagnostic per location (see
https://github.com/apple/swift/pull/18402).
Add an abstraction to retrieve a name suitable for display for a given
source location for use with diagnostics, debug locations, and magic
file literals.
Adds the -vfsoverlay frontend option that enables the user to pass
VFS overlay YAML files to Swift. These files define a (potentially
many-layered) virtual mapping on which we predicate a VFS.
Switch all input-based memory buffer reads in the Frontend to the new
FileSystem-based approach.
Introduce three new requests for name lookup operations that avoid performing
type checking/semantic analysis. They work using syntactic information
(e.g., TypeReprs) and AST-level name lookup operations that will (eventually)
avoid and calls back into type checking. The new requests are:
* Retrieve the superclass declaration of a protocol or class declaration. Use
this request for ClassDecl::getSuperclassDecl() and
ProtocolDecl::getSuperclassDecl().
* Retrieve the types “directly referenced” by a particular location in
an inheritance clause. This query is based on looking at the TypeReprs
and performing fairly-minimal lookup, so it does not involve any Type
computations.
* Retrieve the types “directly referenced” by the underlying type of
a typealias. This query allows us to desugar a typealias without forming
a type.
Along with these is a core operation to transform a set of TypeDecl*s
into a set of NominalTypeDecl*s, looking through typealiases, and
without involving Type at all. The superclass-decl request does this
to find a ClassDecl; other requests will eventually do this to (e.g.)
find all of the protocols mentioned in an inheritance clause.
Most keys are string literals and if they are converted directly to
StringRef, the string length can be computed at compile time, increasing
performance.
For ScalarTraits, a buffer was always created on the heap to which the
scalar string value was written just to be copied to the output buffer
again. In case the value already exists in a memory buffer it is way
cheaper to avoid the heap allocation and copy it straight to the output
buffer.
...but don't hook it up to anything yet.
This is the very very start of the module stability / textual
interfaces feature described at
https://forums.swift.org/t/plan-for-module-stability/14551/
For now I've just made it a frontend option (not a driver option),
which is good enough for testing.
This flag is based on Clang's -fdebug-prefix-map, which lets the user remap absolute paths in debug info. This is necessary for reproducible builds and allows debugging to work on a different machine than the one that built the code when paths to the source may be different.
Sink the type checker request classes into the AST library, so that
various functions in the AST library can form type-checking requests.
The actual evaluator functions for these requests continue to live
in the Sema library, called via indirection through the function
pointer tables registered with the request-evaluator.
The bundling of the form of a request (e.g., the storage that makes up a request)
with the function that evaluates the request value requires us to perform
ad hoc indirection to address the AST —> Sema layering violation. For
example, ClassDecl::getSuperclass() calls through the LazyResolver (when
available) to form the appropriate request. This means that we cannot
use the the request-evaluator’s cache when LazyResolver is null, forcing
all cached state into the AST.
Provide the evaluator with a zone-based registration system, where each
request “zone” (e.g., the type checker’s requests) registers
callbacks to evaluate each kind of request within that zone. The
evaluator indirects through this table of function pointers, allowing
the request classes themselves to be available at a lower level (AST)
than the functions that perform the computation when the value isn’t
in the cache (e.g., Sema).
We are not taking advantage of the indirection yet; that’ll come in a
follow-up commit.
