With '-sdk-module-cache-path', Swift textual interfaces found in the SDK will be built into a separate SDK-specific module cache.
Clang modules are not yet affected by this change, pending addition of the required API.
The algorithm already performs pairwise checks on module dependencies brought into compilation per-source-file. Previously, the algorithm considered the entire sub-graph of a given source file. Actual source compiles do not consider the full transitive module dependency set for cross-import-overlay lookup, but rather only directly-imported modules in a given source file, and '@_exported import' Swift transitive dependencies.
This change adds tracking of whether a given import statement is 'exported' to the dependency scanner and then refines the cross-import overlay lookup logic to only consider transitive modules that are exported by directly-imported dependencies.
Previous implementation took the entire transitive dependency set and cross-referenced all of its members to determine which ones introduce requried cross-import overlays. That implementation differed from the cross-import overlay loading logic during source compilation, where a corrsponding cross-import overlay module is only requested if the two constituent modules are reachable via direct 'import's from *the same source file*. Meaning the dependency scanner before this change would report cross-import overlay dependencies which never got loaded by the corresponding client source compile.
This change implements a new implementation of cross-import overlay discovery which first computes sub-graphs of module dependencies directly reachable by 'import's for each source file of the module under scan and then performs pairwise cross-import overlay query per each such sub-graph.
Resolves rdar://145157171
Add ability to automatically chaining the bridging headers discovered from all
dependencies module when doing swift caching build. This will eliminate all
implicit bridging header imports from the build and make the bridging header
importing behavior much more reliable, while keep the compatibility at maximum.
For example, if the current module A depends on module B and C, and both B and
C are binary modules that uses bridging header, when building module A,
dependency scanner will construct a new header that chains three bridging
headers together with the option to build a PCH from it. This will make all
importing errors more obvious while improving the performance.
Batch dependency scanning was added as a mechanism to support multiple compilation contexts within a single module dependency graph.
The Swift compiler and the Explicitly-built modules model has long since abandoned this approach and this code has long been stale. It is time to remove it and its associated C API.
This set, belonging to 'ModuleDependenciesCache', is only updated in a critical section behind a lock in the scanner. However, it is queried unsynchronized inside the Clang scanner itself. If an update causes a re-hash to happen, chaose can ensue with concurrent lookups.
Since this set only affects the produced set of results from teh Clang scanning query, we should simply pass in an immutable copy to scanning queries and rely on downstream de-duplication of scanning results.
With this, we can avoid passing in the reference to `ModuleDependenciesCache` to the 'scanFilesystemFor*ModuleDependency' altogether.
Resolves rdar://139414443
This change refactors the top-level dependency scanning flow to follow the following procedure:
Scan():
1. From the source target under scan, query all imported module identifiers for a *Swift* module. Leave unresolved identifiers unresolved. Proceed transitively to build a *Swift* module dependency graph.
2. Take every unresolved import identifier in the graph from (1) and, assuming that it must be a Clang module, dispatch all of them to be queried in-parallel by the scanner's worker pool.
3. Resolve bridging header Clang module dpendencies
4. Resolve all Swift overlay dependencies, relying on all Clang modules collected in (2) and (3)
5. For the source target under scan, use all of the above discovered module dependencies to resolve all cross-import overlay dependencies
Add function to handle all macro dependencies kinds in the scanner,
including taking care of the macro definitions in the module interface
for its client to use. The change involves:
* Encode the macro definition inside the binary module
* Resolve macro modules in the dependencies scanners, including those
declared inside the dependency modules.
* Propagate the macro defined from the direct dependencies to track
all the potentially available modules inside a module compilation.
The decision to exclude `-Xcc -D` options from swift module hash
actually doesn't help to solve the problem. It wouldn't reduce the
module variants (or the number of swiftmodule build commands) because
the command-line also encodes all the clang PCM dependencies that do get
affected by `-Xcc` flags.
To avoid the false sharing and the nondeterministic build products,
include most of the `-Xcc` flags, except include search path, into swift
module hash.
rdar://132046247
When dependency scanner construct the overlay file path for the
swift-frontend invocation, make sure the path is remapped if prefix map
is used.
rdar://131940130
When the swiftmodule is built with different clang importer arguments,
they can have the same module hash, causing them to be wrongly re-used even
they contains different interfaces. Add ReducedExtraArgs to the module hash to
disambiguate them.
However, some Xcc arguments, most commonly `-D` options do not affect the
swiftmodule being generated. Do not pass `-Xcc -DARGS` to swift
interface compilation to reduce the amount of module variants in the
build.
rdar://131408266
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
Teach dependency scanner to report all the module canImport check result
to swift-frontend, so swift-frontend doesn't need to parse swiftmodule
or parse TBD file to determine the versions. This ensures dependency
scanner and swift-frontend will have the same resolution for all
canImport checks.
This also fixes two related issues:
* Previously, in order to get consistant results between scanner and
frontend, scanner will request building the module in canImport check
even it is not imported later. This slightly alters the definition of
the canImport to only succeed when the module can be found AND be
built. This also can affect the auto-link in such cases.
* For caching build, the location of the clang module is abstracted away
so swift-frontend cannot locate the TBD file to resolve
underlyingVersion.
rdar://128067152
This change modifies the dependency scanner to keep track of source locations of each encountered 'import' statement, in order to be able to emit diagnostics with source locations if an import failed to resolve.
- Keep track of each 'import' statement's source buffer, line number, and column number when adding it. The dependency scanner utilizes separate compilation instances, and therefore separate Source Managers for scanning `import` statements of user sources and textual interfaces of Swift dependencies. Since import resolution may happen in the main scanner compilation instance while the `import` itself was found by an interface-scanning sub-instance, we cannot simply hold on to the import's `SourceLoc`.
- Add libSwiftScan API for diagnostics to carry above source locations to clients.
Teach dependency scanner to pass cross import overlay file to
swift-frontend for main module compilation. This allows swift-frontend
not to repeat the file system search for overlay files when loading
modules.
This also fixes the issue when caching is enabled, the cross import
doesn't work when the first module is a clang module because the module
built with caching using clang include tree does not preserve
DefinitionLoc which is used to inferred the modulemap location for cross
import overlay search.
rdar://127844120
Improve swift dependency scanner by validating and selecting dependency
module into scanner. This provides benefits that:
* Build system does not need to schedule interface compilation task if
the candidate module is picked, it can just use the candidate module
directly.
* There is no need for forwarding module in the explicit module build.
Since the build system is coordinating the build, there is no need for
the forwarding module in the module cache to avoid duplicated work,
* This also correctly supports all the module loading modes in the
dependency scanner.
This is achieved by only adding validate and up-to-date binary module as
the candidate module for swift interface module dependency. This allows
caching build to construct the correct dependency in the CAS. If there
is a candidate module for the interface module, dependency scanner will
return a binary module dependency in the dependency graph.
The legacy behavior is mostly preserved with a hidden frontend flag
`-no-scanner-module-validation`, while the scanner output is mostly
interchangeable with new scanner behavior with `prefer-interface` module
loading mode except the candidate module will not be returned.
rdar://123711823
Add support for cross import modules by ingesting swiftoverlay files for
the cross import into CAS file system.
The long-term better fix will be just passing the cross import
information from scanner to swift-frontend so frontend doesn't need to
read overlay files again to figure out the cross import module.
rdar://123839248
Add an experimental option to tell dependency scanner to report clang
cc1 args should be used to construct clang importer in all constructed
swift-frontend tasks.
When caching build is enabled, teach dependency scanner to report
command-lines with `-direct-clang-cc1-module-build` so the later
compilation can instantiate clang importer with cc1 args directly. This
avoids running clang driver code, which might involve file system
lookups, which are the file deps that are not captured and might result
in different compilation mode.
rdar://119275464
Otherwise they may have module dependencies of their own which will not be detected by the scanner and included in the list of explicit inputs for compilation.
A swiftmodule can only be correctly ingested by a compiler
that has a matching state of using or not-using
NoncopyableGenerics.
The reason for this is fundamental: the absence of a Copyable
conformance in the swiftmodule indicates that a type is
noncopyable. Thus, if a compiler with NoncopyableGenerics
reads a swiftmodule that was not compiled with that feature,
it will think every type in that module is noncopyable.
Similarly, if a compiler with NoncopyableGenerics produces a
swiftmodule, there will be Copyable requirements on each
generic parameter that the compiler without the feature will
become confused about.
The solution here is to trigger a module mismatch, so that
the compiler re-generates the swiftmodule file using the
swiftinterface, which has been kept compatible with the compiler
regardless of whether the feature is enabled.
Previously, canImport lookup is not completely working with explicit
module due to two issues:
* For clang modules, canImport check still do a full modulemap lookup
which is repeated work from scanner. For caching builds, this lookup
cannot be performed because all modulemap and search path are dropped
after scanning.
* For swift module, if the canImport module was never actually imported
later, this canImport check will fail during the actual compilation,
causing different dependencies in the actual compilation.
To fix the problem, first unified the lookup method for clang and swift
module, which will only lookup the module dependencies reported by
scanner to determine if `canImport` succeed or not. Secondly, add all
the successful `canImport` check modules into the dependency of the
current module so this information can be used during actual
compilation.
Note the behavior change here is that if a module is only checked in
`canImport` but never imported still needs to be built. Comparing to
implicit module build, this can bring in additional clang modules if
they are only check inside `canImport` but should not increase work for
swift modules (where binary module needs to be on disk anyway) or the
most common usecase for `canImport` which is to check the same module
before importing.
rdar://121082031
