I have been using this in a bunch of places in the compiler and rather than
implement it by hand over and over (and maybe messing up), this commit just
commits a correct implementation.
This data structure is a map backed by a vector like data structure. It has two
phases:
1. An insertion phase when the map is mutable and one inserts (key, value) pairs
into the map. These are just appeneded into the storage array.
2. A frozen stage when the map is immutable and one can now perform map queries
on the multimap.
The map transitions from the mutable, thawed phase to the immutable, frozen
phase by performing a stable_sort of its internal storage by only the key. Since
this is a stable_sort, we know that the relative insertion order of values is
preserved if their keys equal. Thus the sorting will have created contiguous
regions in the array of values, all mapped to the same key, that are insertion
order. Thus by finding the lower_bound for a given key, we are guaranteed to get
the first element in that continguous range. We can then do a forward search to
find the end of the region, allowing us to then return an ArrayRef to these
internal values.
The reason why I keep on finding myself using this is that this map enables one
to map a key to an array of values without needing to store small vectors in a
map or use heap allocated memory, all key, value pairs are stored inline (in
potentially a single SmallVector given that one is using SmallFrozenMultiMap).
MSVC did not like the original code and would fail to build as:
```
swift\include\swift/Basic/Located.h(50): error C2995: 'bool swift::operator ==(const swift::Located<T> &,const swift::Located<T> &)': function template has already been defined
swift\include\swift/Basic/Located.h(50): note: see declaration of 'swift::operator =='
llvm\include\llvm/Support/TrailingObjects.h(76): note: see reference to class template instantiation 'swift::Located<swift::Identifier>' being compiled
llvm\include\llvm/Support/TrailingObjects.h(233): note: see reference to class template instantiation 'llvm::trailing_objects_internal::AlignmentCalcHelper<swift::Located<swift::Identifier>>' being compiled
swift\include\swift/AST/Decl.h(1512): note: see reference to class template instantiation 'llvm::TrailingObjects<swift::ImportDecl,swift::Located<swift::Identifier>>' being compiled
```
The original code is odd. There appears to be some unnecessary
complexity.
First, the member function is marked as a friend of a
`struct` type which does not change the member's visibility, thus all
the members are `public`, and the function need not be friended.
Second, the function is templated over the same parameter type, which
means that the original template parameter could be used and the
standard member equality operator could be used rather than the
free-standing form.
It is unclear why the member equality operator is insufficient, and the
extraneous template instatiations here seem wasteful. Out-of-line the
free-standing form and not mark it as a friend to restore the build.
Switching to a member form can be a follow up change.
Restructure fine-grained-dependencies to enable unit testing
Get frontend to emit correct swiftdeps file (fine-grained when needed) and only emit dot file for -emit-fine-grained-dependency-sourcefile-dot-files
Use deterministic order for more information outputs.
Set EnableFineGrainedDependencies consistently in frontend.
Tolerate errors that result in null getExtendedNominal()
Fix memory issue by removing node everywhere.
Break up print routine
Be more verbose so it will compile on Linux.
Sort batchable jobs, too.
VS2015 had an issue with the deletion of an operator. Since VS2017 is
the minimum version that LLVM uses, we can assume that VS2017+ is in use
(_MSC_VER >= 1910). Clean up the now defunct workaround.
When symbols are moved to this module, this module declares them as HIDE
for the OS versions prior to when the move happened. On the other hand, the
original module should declare ADD them for these OS versions. An executable
can choose the right library to link against depending on the deployment target.
This is a walk-around that linker directives cannot specify other install
name per symbol, we should eventually remove this.
The platform versions are really only used on Darwin platforms.
Simplify the path by defaulting to `0.0.0` on all platforms, and
handling the version number on supported platforms.
Note: The change in ASTBuilder::createFunctionType is functionally minor,
but we need the FunctionType::Params computed _before_ the ExtInfo, so we
need to shuffle a bunch of code around.
`IntRange::iterator::operator==` must be marked as `const` in order to use
`OptionalTransformRange<IntRange<...>, ...>::empty` under specific conditions.
