…uses
The Flang implemenation of OpenACC uses a .td file in the llvm/Frontend
directory to determine appertainment in 4 categories:
-Required: If this list has items in it, the directive requires at least
1 of these be present.
-AllowedExclusive: Items on this list are all allowed, but only 1 from
the list may be here (That is, they are exclusive of eachother).
-AllowedOnce: Items on this list are all allowed, but may not be
duplicated.
Allowed: Items on this list are allowed. Note th at the actual list of
'allowed' is all 4 of these lists together.
This is a draft patch to swtich Clang over to use those tables. Surgery
to get this to happen in Clang Sema was somewhat reasonable. However,
some gaps in the implementations are obvious, the existing clang
implementation disagrees with the Flang interpretation of it. SO, we're
keeping a task list here based on what gets discovered.
Changes to Clang:
- [x] Switch 'directive-kind' enum conversions to use tablegen See
ff1a7bddd9435b6ae2890c07eae60bb07898bbf5
- [x] Switch 'clause-kind' enum conversions to use tablegen See
ff1a7bddd9435b6ae2890c07eae60bb07898bbf5
- [x] Investigate 'parse' test differences to see if any new
disagreements arise.
- [x] Clang/Flang disagree as to whether 'collapse' can be multiple
times on a loop. Further research showed no prose to limit this, and the
comment on the clang implementation said "no good reason to allow", so
no standards justification.
- [x] Clang/Flang disagree whether 'num_gangs' can appear >1 on a
compute/combined construct. This ended up being an unjustified
restriction.
- [x] Clang/Flang disagree as to the list of required clauses on a 'set'
construct. My research shows that Clang mistakenly included 'if' in the
list, and that it should be just 'default_async', 'device_num', and
'device_type'.
- [x] Order of 'at least one of' diagnostic has changed. Tests were
updated.
- [x] Ensure we are properly 'de-aliasing' clause names in appertainment
checks?
- [x] What is 'shortloop'? 'shortloop' seems to be an old non-standard
extension that isn't supported by flang, but is parsed for backward
compat reasons. Clang won't parse, but we at least have a spot for it in
the clause list.
- [x] Implemented proposed change for 'routine' gang/worker/vector/seq.
(see issue 539)
- [x] Implement init/shutdown can only have 1 'if' (see issue 540)
- [x] Clang/Flang disagree as to whether 'tile' is permitted more than
once on a 'loop' or combined constructs (Flang prohibits >1). I see no
justification for this in the standard. EDIT: I found a comment in clang
that I did this to make SOMETHING around duplicate checks easier.
Discussion showed we should actually have a better behavior around
'device_type' and duplicates, so I've since implemented that.
- [x] Clang/Flang disagree whether 'gang', 'worker', or 'vector' may
appear on the same construct as a 'seq' on a 'loop' or 'combined'. There
is prose for this in 2022: (a gang, worker, or vector clause may not
appear if a 'seq' clause appears). EDIT: These don't actually disagree,
but aren't in the .td file, so I restored the existing code to do this.
- [x] Clang/Flang disagree on whether 'bind' can appear >1 on a
'routine'. I believe line 3096 (A bind clause may not bind to a routine
name that has a visible bind clause) makes this limitation (Flang
permits >1 bind). we discussed and decided this should have the same
rules as worker/vector/etc, except without the 'exactly 1 of' rule (so
no dupes in individual sections).
- [x] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_num' clauses. I believe there is no supporting prose
for this limitation., We decided that `device_num` should only happen
1x.
- [x] Clang/Flang disagree whether 'num_gangs' can appear >1 on a
'kernels' construct. Line 1173 (On a kernels construct, the num_gangs
clause must have a single argument) justifies limiting on a
per-arguement basis, but doesn't do so for multiple num_gangs clauses.
WE decided to do this with the '1-per-device-type' region for num_gangs,
num_workers, and vector_length, see openacc bug here:
https://github.com/OpenACC/openacc-spec/issues/541
Changes to Flang:
- [x] Clang/Flang disgree on whether 'atomic' can take an 'if' clause.
This was added in OpenACC3.3_Next See #135451
- [x] Clang/Flang disagree on whether 'finalize' can be allowed >1 times
on a 'exit_data' construct. see #135415.
- [x] Clang/Flang disagree whether 'if_present' should be allowed >1
times on a 'host_data'/'update' construct. see #135422
- [x] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_type' clauses. I believe there is no supporting prose
for this limitation.
- [ ] SEE change for num_gangs/etc above.
Changes that need discussion/research:
This PR reland https://github.com/llvm/llvm-project/pull/135808, fixed
some missed changes in LLDB.
I found this issue when I working on
https://github.com/llvm/llvm-project/pull/107168.
Currently we have many similiar data structures like:
- std::pair<IdentifierInfo *, SourceLocation>.
- Element type of ModuleIdPath.
- IdentifierLocPair.
- IdentifierLoc.
This PR unify these data structures to IdentifierLoc, moved
IdentifierLoc definition to SourceLocation.h, and deleted other similer
data structures.
---------
Signed-off-by: yronglin <yronglin777@gmail.com>
We emit a macro definition only in a module defining it. But it means
that if another module has an identifier with the same name as the
macro, the users of such module won't be able to use the macro anymore.
Fix by storing that an identifier has a macro definition that's not in a
current module (`MacroDirectivesOffset == 0`). This way
`IdentifierLookupVisitor` knows not to stop at the first module with an
identifier but to keep checking included modules for the actual macro
definition.
Fixes issue #32040.
rdar://30258278
Reverts llvm/llvm-project#135808
Example from the LLDB macOS CI:
https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/as-lldb-cmake/24084/execution/node/54/log/?consoleFull
```
/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/source/Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.cpp:360:49: error: no viable conversion from 'std::pair<clang::IdentifierInfo *, clang::SourceLocation>' to 'clang::ModuleIdPath' (aka 'ArrayRef<IdentifierLoc>')
clang::Module *top_level_module = DoGetModule(clang_path.front(), false);
^~~~~~~~~~~~~~~~~~
/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:41:40: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'std::pair<clang::IdentifierInfo *, clang::SourceLocation>' to 'const llvm::ArrayRef<clang::IdentifierLoc> &' for 1st argument
class LLVM_GSL_POINTER [[nodiscard]] ArrayRef {
^
/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:41:40: note: candidate constructor (the implicit move constructor) not viable: no known conversion from 'std::pair<clang::IdentifierInfo *, clang::SourceLocation>' to 'llvm::ArrayRef<clang::IdentifierLoc> &&' for 1st argument
/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:70:18: note: candidate constructor not viable: no known conversion from 'std::pair<clang::IdentifierInfo *, clang::SourceLocation>' to 'std::nullopt_t' for 1st argument
/*implicit*/ ArrayRef(std::nullopt_t) {}
```
I found this issue when I working on
https://github.com/llvm/llvm-project/pull/107168.
Currently we have many similiar data structures like:
- `std::pair<IdentifierInfo *, SourceLocation>`.
- Element type of `ModuleIdPath`.
- `IdentifierLocPair`.
- `IdentifierLoc`.
This PR unify these data structures to `IdentifierLoc`, moved
`IdentifierLoc` definition to SourceLocation.h, and deleted other
similer data structures.
---------
Signed-off-by: yronglin <yronglin777@gmail.com>
With implicitly-built modules, seeing something like:
```
fatal error: module 'X' is defined in both '<cache>/HASH1/X-HASH2.pcm' and '<cache>/HASH1/X-HASH3.pcm'
```
is super confusing and not actionable, because the module cache tends to
be hidden from the developer.
This PR adds a note to that diagnostic that names the module map files
the PCM files were compiled from, hopefully giving a good enough hint
for further investigation:
```
note: compiled from '<build>/X.framework/Modules/module.modulemap' and '<SDK>/X.framework/Modules/module.modulemap'
```
(I had to replace the mechanism used to convert `DiagnosticError` into
something `DiagnosticsEngine` can understand, because it seemingly did
not support notes.)
When a module is being scanned, it can depend on modules that have
already been built from a pch dependency. When this happens, the pcm
files are reused for the module dependencies. When this is the case,
check if input files recorded from the PCMs come from the provided
stable directories transitively since the scanner will not have access
to the full set of file dependencies from prebuilt modules.
Fix https://github.com/llvm/llvm-project/issues/132059.
Providing incorrect mappings via `-fmodule-file=<name>=<path/to/bmi>`
can crash the compiler when loading a module that imports an
incorrectly mapped module.
The crash occurs during AST body deserialization, when the compiler
attempts to resolve remappings using the `ModuleFile` from the
incorrectly mapped module's BMI file.
The cause is an invalid access into an incorrectly loaded
`ModuleFile`.
This commit fixes the issue by verifying the identity of the imported
module.
OpenACC 3.3-NEXT has changed the way tags for copy, copyin, copyout, and
create clauses are specified, and end up adding a few extras, and
permits them as a list. This patch encodes these as bitmask enum so
they can be stored succinctly, but still diagnose reasonably.
This introduces a new class 'UnsignedOrNone', which models a lite
version of `std::optional<unsigned>`, but has the same size as
'unsigned'.
This replaces most uses of `std::optional<unsigned>`, and similar
schemes utilizing 'int' and '-1' as sentinel.
Besides the smaller size advantage, this is simpler to serialize, as its
internal representation is a single unsigned int as well.
Fix for regression #130917, changes in #111992 were too broad. This change reduces scope of previous fix. Added `ExternalASTSource::wasThisDeclarationADefinition` to detect cases when FunctionDecl lost body due to declaration merges.
The File ID is incorrectly calculated, resulting in an out-of-bounds
access. The test code is more complex because the File fetching only
happens in specific scenarios.
---------
Co-authored-by: ShaderKeeper <no-reply@shaderkeeper.com>
Co-authored-by: Chuanqi Xu <yedeng.yd@linux.alibaba.com>
Original PR: #130537
Originally reverted due to revert of dependent commit. Relanding with no
changes.
This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the base class.
Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.
The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntatically, and
they represent the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.
This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.
As usual, includes a few drive-by fixes in order to make use of the
improvements.
This is the last item of the OpenACC 3.3 spec. It includes the
implicit-name version of 'routine', plus significant refactorings to
make the two work together. The implicit name version is represented as
an attribute on the function call. This patch also implements the
clauses for the implicit-name version, as well as the A.3.4 warning.
Fix#132371
Minor error , sanitizer builds are failing for unused variable.
sanitizer-aarch64-linux/build/llvm-project/clang/lib/Serialization/ASTReader.cpp:11764:17:
error: unused variable 'I' [-Werror,-Wunused-variable]
11764 | for (unsigned I : llvm::seq<unsigned>(NumFlags))
This was modified as part of
[https://github.com/llvm/llvm-project/pull/129938](https://github.com/llvm/llvm-project/pull/129938)
, which got missed.
Co-authored-by: Chandra Ghale <ghale@pe31.hpc.amslabs.hpecorp.net>
Initial Parse/Sema support for reduction over private variable with
reduction clause.
Section 7.6.10 in in OpenMP 6.0 spec.
- list item in a reduction clause can now be private in the enclosing
context.
- Added support for _original-sharing-modifier_ with reduction clause.
---------
Co-authored-by: Chandra Ghale <ghale@pe31.hpc.amslabs.hpecorp.net>
Original PR: #130537
Reland after updating lldb too.
This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the base class.
Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.
The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntatically, and
they represent the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.
This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.
As usual, includes a few drive-by fixes in order to make use of the
improvements.
This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the class.
Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.
The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntactically, and it
also represents the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.
This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.
As usual, includes a few drive-by fixes in order to make use of the
improvements, and removing some duplications, for example
CheckBaseClassAccess is deduplicated from across SemaAccess and
SemaCast.
`ASTReader::FinishedDeserializing` uses `NumCurrentElementsDeserializing` to keep track of nested `Deserializing` RAII actions. The `FinishedDeserializing` only performs actions if it is the top-level `Deserializing` layer. This works fine in general, but there is a problematic edge case.
If a call to `redecls()` in `FinishedDeserializing` performs deserialization, we re-enter `FinishedDeserializing` while in the middle of the previous `FinishedDeserializing` call.
The known problematic part of this is that this inner `FinishedDeserializing` can go all the way to `PassInterestingDeclsToConsumer`, which operates on `PotentiallyInterestingDecls` data structure which contain decls that should be handled by the previous `FinishedDeserializing` stage.
The other shared data structures are also somewhat concerning at a high-level in that the inner `FinishedDeserializing` would be handling pending actions that are not "within its scope", but this part is not known to be problematic.
We already have a guard within `PassInterestingDeclsToConsumer` because we can end up with recursive deserialization within `PassInterestingDeclsToConsumer`. The implemented solution is to apply this guard to the portion of `FinishedDeserializing` that performs further deserialization as well. This ensures that recursive deserialization does not trigger `PassInterestingDeclsToConsumer` which may operate on entries that are not ready to be passed.
This PR adds new `ModuleCache` interface to Clang's implicitly-built
modules machinery. The main motivation for this change is to create a
second implementation that uses a more efficient kind of
`llvm::AdvisoryLock` during dependency scanning.
In addition to the lock abstraction, the `ModuleCache` interface also
manages the existing `InMemoryModuleCache` instance. I found that
compared to keeping these separate/independent, the code is a bit
simpler now, since these are two tightly coupled concepts. I can
envision a more efficient implementation of the `InMemoryModuleCache`
for the single-process case too, which will be much easier to implement
with the current setup.
This is not intended to be a functional change.
The 'bind' clause allows the renaming of a function during code
generation. There are a few rules about when this can/cannot happen,
and it takes either a string or identifier (previously mis-implemetned
as ID-expression) argument.
Note there are additional rules to this in the implicit-function routine
case, but that isn't implemented in this patch, as implicit-function
routine is not yet implemented either.
'nohost' is only valid on routine, and states that the compiler
shouldn't compile this routine for the host. It has no arguments, so no
checking is required besides putting it in the AST.
These 4 clauses are mutually exclusive, AND require at least one of
them. Additionally, gang has some additional restrictions in that only
the 'dim' specifier is permitted. This patch implements all of this, and
ends up refactoring the handling of each of these clauses for
readabililty.
Static analysis flags the final return statement in `ReadExtensionBlock`
as unreachable and indeed it is since there is no way to exit the
`while(true)` loop besides a *return statement*.
So I am converting it into a `llvm_unreachable` to explicitly document
this.
The 'declare' construct is the first of two 'declaration' level
constructs, so it is legal in any place a declaration is, including as a
statement, which this accomplishes by wrapping it in a DeclStmt. All
clauses on this have a 'same scope' requirement, which this enforces as
declaration context instead, which makes it possible to implement these
as a template.
The 'link' and 'device_resident' clauses are also added, which have some
similar/small restrictions, but are otherwise pretty rote.
This patch implements all of the above.
This makes it significantly easier to add new builtin templates, since
you only have to modify two places instead of a dozen or so.
The `BuiltinTemplates.td` could also be extended to generate
documentation from it in the future.
…ete decl chains until the end of `finishPendingActions`. (#121245)"
This reverts commit a9e249f64e800fbb20a3b26c0cfb68c1a1aee5e1.
Reverting this change because of issue #126973.
Add initial parsing/sema support for new assumption clause so clause can
be specified. For now, it's ignored, just like the others.
Added support for 'no_openmp_construct' to release notes.
Testing
- Updated appropriate LIT tests.
- Testing: check-all
The call to `hasBody` inside `finishPendingActions` that bumps the `PendingIncompleteDeclChains`
size from `0` to `1`, and also sets the `LazyVal->LastGeneration` to `6` which matches
the `LazyVal->ExternalSource->getGeneration()` value of `6`. Later, the iterations over `redecls()`
(which calls `getNextRedeclaration`) is expected to trigger the reload, but it **does not** since
the generation numbers match.
The proposed solution is to perform the marking of incomplete decl chains at the end of `finishPendingActions`.
This way, **all** of the incomplete decls are marked incomplete as a post-condition of `finishPendingActions`.
It's also safe to delay this operation since any operation being done within `finishPendingActions` has
`NumCurrentElementsDeserializing == 1`, which means that any calls to `CompleteDeclChain` would simply
add to the `PendingIncompleteDeclChains` without doing anything anyway.
This is take two of #70976. This iteration of the patch makes sure that
custom
diagnostics without any warning group don't get promoted by `-Werror` or
`-Wfatal-errors`.
This implements parts of the extension proposed in
https://discourse.llvm.org/t/exposing-the-diagnostic-engine-to-c/73092/7.
Specifically, this makes it possible to specify a diagnostic group in an
optional third argument.
This reverts commit c3ba6f378ef80d750e2278560c6f95a300114412.
We are seeing performance regressions of up to 40% on some compilations
with this patch, we will investigate and reland after fixing performance
issues.
…ecord level.
This fixes the incorrect diagnostic emitted when compiling the following
snippet
```
// string_view.h
template<class _CharT>
class basic_string_view;
typedef basic_string_view<char> string_view;
template<class _CharT>
class
__attribute__((__preferred_name__(string_view)))
basic_string_view {
public:
basic_string_view()
{
}
};
inline basic_string_view<char> foo()
{
return basic_string_view<char>();
}
// A.cppm
module;
#include "string_view.h"
export module A;
// Use.cppm
module;
#include "string_view.h"
export module Use;
import A;
```
The diagnostic is
```
string_view.h:11:5: error: 'basic_string_view<char>::basic_string_view' from module 'A.<global>' is not present in definition of 'string_view' provided earlier
```
The underlying issue is that deserialization of the `preferred_name`
attribute triggers deserialization of `basic_string_view<char>`, which
triggers the deserialization of the `preferred_name` attribute again
(since it's attached to the `basic_string_view` template).
The deserialization logic is implemented in a way that prevents it from
going on a loop in a literal sense (it detects early on that it has
already seen the `string_view` typedef when trying to start its
deserialization for the second time), but leaves the typedef
deserialization in an unfinished state. Subsequently, the `string_view`
typedef from the deserialized module cannot be merged with the same
typedef from `string_view.h`, resulting in the above diagnostic.
This PR resolves the problem by delaying the deserialization of the
`preferred_name` attribute until the deserialization of the
`basic_string_view` template is completed. As a result of deferring, the
deserialization of the `preferred_name` attribute doesn't need to go on
a loop since the type of the `string_view` typedef is already known when
it's deserialized.
Close https://github.com/llvm/llvm-project/issues/90154
This patch is also an optimization to the lookup process to utilize the
information provided by `export` keyword.
Previously, in the lookup process, the `export` keyword only takes part
in the check part, it doesn't get involved in the lookup process. That
said, previously, in a name lookup for 'name', we would load all of
declarations with the name 'name' and check if these declarations are
valid or not. It works well. But it is inefficient since it may load
declarations that may not be wanted.
Note that this patch actually did a trick in the lookup process instead
of bring module information to DeclarationName or considering module
information when deciding if two declarations are the same. So it may
not be a surprise to me if there are missing cases. But it is not a
regression. It should be already the case. Issue reports are welcomed.
In this patch, I tried to split the big lookup table into a lookup table
as before and a module local lookup table, which takes a combination of
the ID of the DeclContext and hash value of the primary module name as
the key. And refactored `DeclContext::lookup()` method to take the
module information. So that a lookup in a DeclContext won't load
declarations that are local to **other** modules.
And also I think it is already beneficial to split the big lookup table
since it may reduce the conflicts during lookups in the hash table.
BTW, this patch introduced a **regression** for a reachability rule in
C++20 but it was false-negative. See
'clang/test/CXX/module/module.interface/p7.cpp' for details.
This patch is not expected to introduce any other
regressions for non-c++20-modules users since the module local lookup
table should be empty for them.
Close https://github.com/llvm/llvm-project/issues/90154
This patch is also an optimization to the lookup process to utilize the
information provided by `export` keyword.
Previously, in the lookup process, the `export` keyword only takes part
in the check part, it doesn't get involved in the lookup process. That
said, previously, in a name lookup for 'name', we would load all of
declarations with the name 'name' and check if these declarations are
valid or not. It works well. But it is inefficient since it may load
declarations that may not be wanted.
Note that this patch actually did a trick in the lookup process instead
of bring module information to DeclarationName or considering module
information when deciding if two declarations are the same. So it may
not be a surprise to me if there are missing cases. But it is not a
regression. It should be already the case. Issue reports are welcomed.
In this patch, I tried to split the big lookup table into a lookup table
as before and a module local lookup table, which takes a combination of
the ID of the DeclContext and hash value of the primary module name as
the key. And refactored `DeclContext::lookup()` method to take the
module information. So that a lookup in a DeclContext won't load
declarations that are local to **other** modules.
And also I think it is already beneficial to split the big lookup table
since it may reduce the conflicts during lookups in the hash table.
BTW, this patch introduced a **regression** for a reachability rule in
C++20 but it was false-negative. See
'clang/test/CXX/module/module.interface/p7.cpp' for details.
This patch is not expected to introduce any other
regressions for non-c++20-modules users since the module local lookup
table should be empty for them.
---
On the API side, this patch unfortunately add a maybe-confusing argument
`Module *NamedModule` to
`ExternalASTSource::FindExternalVisibleDeclsByName()`. People may think
we can get the information from the first argument `const DeclContext
*DC`. But sadly there are declarations (e.g., namespace) can appear in
multiple different modules as a single declaration. So we have to add
additional information to indicate this.
The 'align' modifier is now accepted in the 'allocate' clause. Added LIT
tests covering codegen, PCH, template handling, and serialization for
'align' modifier.
Added support for align-modifier to release notes.
Testing
- New allocate modifier LIT tests.
- OpenMP LIT tests.
- check-all
These two clauses just take a 'var-list' and specify where the variables
should be copied from/to. This patch implements the AST nodes for them
and ensures they properly take a var-list.
The 'self' clause is an unfortunately difficult one, as it has a
significantly different meaning between 'update' and the other
constructs. This patch introduces a way for the 'self' clause to work
as both. I considered making this two separate AST nodes (one for
'self' on 'update' and one for the others), however this makes the
automated macros/etc for supporting a clause break.
Instead, 'self' has the ability to act as either a condition or as a
var-list clause. As this is the only one of its kind, it is implemented
all within it. If in the future we have more that work like this, we
should consider rewriting a lot of the macros that we use to make
clauses work, and make them separate ast nodes.
A fairly simple one, only valid on the 'set' construct, this clause
takes an int expression. Most of the work was already done as a part of
parsing, so this patch ends up being a lot of infrastructure.
This is a very simple sema implementation, and just required AST node
plus the existing diagnostics. This patch adds tests and adds the AST
node required, plus enables it for 'init' and 'shutdown' (only!)
