This refactoring allows us to drop ModuleInterfaceLoader when explicit modules
are enabled. Before this change, the dependencies scanner needs the loader to be
present to access functionalities like collecting prebuilt module candidates.
We need ClangImporterOptions to be persistent for several scenarios: (1)
when creating a sub-ASTContext to build Swift modules from interfaces; and
(2) when creating a new Clang instance to invoke Clang dependencies scanner.
This change is NFC.
In the fast dependency scanner, depending on whether a module intrface was found via the import search path or framework search path, encode into the dependency graph Swift module details, whether a given module is a framework.
* Remove dead ModuleSourceInfoFilename parameters
These were never actually used; we might find a way to bring them back later.
* Introduce SerializedModuleBaseName
This is intended to replace the _n_ filename parameters that tend to get passed around in the SerializedModuleLoader classes.
* Manipulate currPath in SerializedModuleLoader less often
* Don’t pass raw paths around SerializedModuleLoader
Only pass base names.
* Regularize module file opening functions
✔ More informative error messages in case of crashes.
✔ Handling and documenting different cases.
✔ Test cases for different cases.
✔ Make SDKDependencies.swift pass again.
After setting up the .swiftsourceinfo file, this patch starts to actually serialize
and de-serialize source locations for declaration. The binary format of .swiftsourceinfo
currently contains these three records:
BasicDeclLocs: a hash table mapping from a USR ID to a list of basic source locations. The USR id
could be retrieved from the following DeclUSRs record using an actual decl USR. The basic source locations
include a file ID and the results from Decl::getLoc(), ValueDecl::getNameLoc(), Decl::getStartLoc() and Decl::getEndLoc().
The file ID could be used to retrieve the actual file name from the following SourceFilePaths record.
Each location is encoded as a line:column pair.
DeclUSRS: a hash table mapping from USR to a USR ID used by location records.
SourceFilePaths: a hash table mapping from a file ID to actual file name.
BasicDeclLocs should be sufficient for most diagnostic cases. If additional source locations
are needed, we could always add new source location records without breaking the backward compatibility.
When de-serializing the source location from a module-imported decl, we calculate its USR, retrieve the USR ID
from the DeclUSRS record, and use the USR ID to look up the basic location list in the BasicDeclLocs record.
For more details about .swiftsourceinfo file: https://forums.swift.org/t/proposal-emitting-source-information-file-during-compilation
The clang importer has to deal with two virtual file systems, one coming
from clang, and one coming from swift. Currently, if both are set, we
emit a diagnostic that we'll pick the swift one.
This commit changes that, by merging the two virtual file systems into a
single overlay file system, and using that. To make this possible, we
always initialize the file manager with an overlay file system. In the
clang importer, we then create a new overlay file system, starting with
the one coming from clang, and adding overlays from swift on top.
The motivation for this change is the reproducer infrastructure in LLDB,
which adds a third virtual file system to the mix.
