teemperor added a comment.
> Well, I still don't understand how LLDB synthesis the AST.
> So you have a C++ module in a .pcm file. This means you could create an AST
> from that with ASTReader from it's .clang_ast section, right? In that case
> the AST should be complete with all type information. If this was the case
> then I don't see why it is not possible to use clang::ASTImporter to import
> templates and specializations, since we do exactly that in CTU.
>
> Or do you guys create the AST from the debug info, from the .debug_info
> section of .pcm module file? And this is why AST is incomplete? I've got this
> from
> https://youtu.be/EgkZ8PTNSHQ?list=PL85Cf-ok7HpppFWlp2wX_-A1dkyFVlaEB&t=1565
> If this is the case, then comes my naiive quiestion: Why don't you use the
> ASTReader?
There are no C++ modules involved in our use case beside the generic `std`
module. No user-written code is read from a module and we don't have any PCM
file beside the `std` module we build for the expression evaluator.
We use the ASTReader to directly read the `std` module contents into the
expression evaluation ASTContext, but this doesn't give us the decls for the
instantiations the user has made (e.g. `std::vector<Foo>`). We only have these
user instantiations in the 'normal' debug info where we have a rather minimal
AST (again, no modules are not involved in building this debug info AST). The
`InternalImport` in the LLDB patch just stitches the module AST and the debug
info AST together when we import something that we also have (in better quality
from the C++ module) in the target ASTContext.
================
Comment at: clang/unittests/AST/ASTImporterTest.cpp:581
+struct RedirectingImporter : public ASTImporter {
+ using ASTImporter::ASTImporter;
+ // Returns a ImporterConstructor that constructs this class.
----------------
balazske wrote:
> Is this `using` needed?
Yeah, otherwise we have to provide our own constructor that essentially just
forwards to the ASTImporter constructor.
================
Comment at: clang/unittests/AST/ASTImporterTest.cpp:588
+ bool MinimalImport, ASTImporterLookupTable *LookupTabl) {
+ return static_cast<ASTImporter *>(
+ new RedirectingImporter(ToContext, ToFileManager, FromContext,
----------------
balazske wrote:
> The `static_cast` should not be needed.
Thanks!
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59485/new/
https://reviews.llvm.org/D59485
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