The async stepping blob's first field is the compiler-generated catch
handler's IL offset plus one, and 0 when there is nothing to record. ILSpy
wrote the raw offset, so a consumer decoding it as (value - 1) resolved an
address in the middle of an instruction: Mono.Cecil throws
ArgumentNullException while reading the body, which is why the reported
assembly opened in ILSpy but killed ILLink on every MoveNext it had.
CatchHandlerOffset now holds the offset it is named after, or -1 for "none",
and BuildBlob applies the bias - the same model the compiler uses.
It is recorded only where an escaping exception is unlikely to be observed:
an async void method, and an async entry point. Recording it more widely
would be worse than recording it nowhere, because an async Task method
returns its exception through the Task and the debugger would then break on
exceptions user code catches. Measured over csc 1.3.2 to 5.10: async void is
handler+1 and a normal async Task is 0 in every version; only async Main
changed, from 0 to handler+1 between 2.10 and 3.11.
The entry point token names the synchronous '<Main>' shim that exists because
the runtime will not take .entrypoint on an async method, so the method to
record is the one the shim calls. Reading that call is exact; matching the
shim's siblings by name is not, and gets a 'Main' overload beside the real
entry point wrong.
Both tests compare against the compiler's own PDB for the same assembly, so
the blobs describe the same IL and the field compares directly.
Assisted-by: Claude:claude-opus-5:Claude Code
With recognition on the ILAst and reference substitution during
translation, the four accessor-body patterns in
PatternStatementTransform were only reachable as a fallback, and any
divergence between them and the AutoEventDecompiler verdict produced
inconsistent output. A compiler shape the ILAst matchers do not know now
degrades to explicit accessors with the backing field kept in the
output, which stays compilable. Bodyless events (abstract, extern,
interface members) previously relied on the patterns' no-body clause to
become field-like; since C# cannot express bodyless custom accessors,
DoDecompile now chooses the field-like form for them directly. Also
deletes the orphaned IsEventBackingFieldName helper; the name
association lives in PropertyAndEventBackingFieldLookup.
Assisted-by: Claude:claude-fable-5:Claude Code
Claude-Session: https://claude.ai/code/session_01Btdypgm8utyxqt1Etn2BDi
A field, auto-property, or event initializer is written once at its
declaration, but in IL it runs in every instance constructor that does not
chain to this(...) (and static initializers run in the static constructor).
The decompiler lifts the initializer from a single constructor, so its
breakpoint was emitted only there and the other constructors had none.
Two causes are addressed:
- The lift discarded the initializer's copies in the other constructors.
They are now kept on MemberInitializerInOtherConstructorsAnnotation and
replayed by SequencePointBuilder, mapping the same source location onto
each constructor's IL.
- PortablePdbWriter only emitted methods that DebugInfoGenerator discovered
through declaration syntax, so a constructor whose declaration is omitted
from the output (implicit default ctor, implicit static ctor, primary
ctor) dropped its generated points. Those functions are now emitted by
walking the sequence-point map directly.
PdbGen fixtures cover single, multiple, this()-chained, implicit, static,
primary-constructor, and field-like event initializers, pinning the
reconstructed breakpoint map against the C# compiler's.
Assisted-by: Claude:claude-opus-4-8:Claude Code
ILFunction.IsAsync is derived from the method signature, so .NET 11
runtime-async methods (MethodImplAsync bit, no MoveNext state machine)
report IsAsync without AsyncAwaitDecompiler ever populating
AsyncDebugInfo. Its Awaits then stays an uninitialized ImmutableArray,
and PortablePdbWriter threw an NRE building the MethodSteppingInformation
blob from that default struct. Runtime-async methods have no yield/resume
offsets to record, so guard on Awaits.IsDefault and omit the blob,
matching the C# compiler, which emits no stepping information for them
either. A genuinely zero-await classic state machine keeps an
initialized empty Awaits and is unaffected.
Assisted-by: Claude:claude-opus-4-8:Claude Code
DebugInfoGenerator asserted that every local variable's decompiled type
is equivalent to the metadata local-signature type at its slot. That
holds at IL-read time but not afterwards: variable splitting gives one
slot several typed variables, pinned-region locals are modeled as
pointers (int* vs int& pinned), and generic-context type-parameter
identity differs. The assertion therefore aborted PDB generation (Debug
builds) for ordinary inputs such as any method with a fixed statement.
The type is never written to the PDB - only the slot index and name are -
so the mismatch cannot affect the debugging experience. The slot index,
the only emitted value, is correct by construction: it is the IL
ldloc/stloc operand, sourced from the signature slot when the variable is
created and copied verbatim by SplitVariables; it is never reassigned.
Keep only the index-bound check and document why the type is not verified.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Decompiler warnings (ILFunction.Warnings, e.g. the DetectPinnedRegions
block-duplication notice) are surfaced as an EmptyStatement carrying only
a comment. VisitEmptyStatement prints no semicolon for it, and
EmptyStatement derives its StartLocation/EndLocation from its Location
field, which is only set when that semicolon token is written. The
statement was therefore left without a text location, and
SequencePointBuilder then asserted on the empty start location while
generating PDB sequence points - aborting PDB generation for any assembly
whose decompilation emits such a warning (e.g. System.Net.Requests).
Point the empty statement at the comment it carries (already printed by
the time the node ends, so its location is known), falling back to the
collapsed end-of-last-token position. Every printed node then has a
location, so the SequencePointBuilder invariant holds without
special-casing, and the statement lines up with the text it represents.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The PDB sequence-point tests were missing real while-loop input, and their residual comparison treated breakpoint locations as an unordered multiset. Add coverage for while/do-while fixtures and compare residuals in sequence order so stepping-order changes are pinned.
Assisted-by: CodeAlta:gpt-5.5:CodeAlta
Extends the breakpoint-map comparison to hidden sequence points, anchoring
each hidden point to the visible point it follows so the descriptor stays
independent of the IL offsets the decompiler reconstructs. Adds PdbGen cases
spanning try/catch/finally, switch, async/await, yield, loops, LINQ, pattern
matching and more, pinning the known residuals where the decompiler folds a
compiler-hidden branch into an adjacent point.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The PdbGen tests compared the reconstructed PDB to the C# compiler's
byte-for-byte, so any non-trivial method failed on reconstructed IL
ranges, hidden sequence points and local scopes - none of which the
decompiler can reproduce exactly. That left four of seven fixtures
[Ignore]d and the suite with almost no coverage.
Compare only what a debugging user actually feels: the visible (non-hidden)
breakpoint map, parsed straight from the sequence-point blobs and keyed by
method-definition row (shared between the PDB and the PE it describes). IL
offsets, hidden points, local scopes and the embedded source are dropped.
The compiler's own PDB is the oracle, so the tests assert correct debugging
behavior rather than the decompiler's past output. Methods where the
decompiler legitimately diverges pin an auto-derived residual snapshot, the
same accept-the-diff workflow as the pretty tests; a separate oracle-free
check rejects duplicate or overlapping sequence points.
Un-ignores ForLoopTests, LambdaCapturing and Members (its source is
regenerated to match the decompiler's per-type output, collapsing ~50 lines
of indentation-induced coordinate noise to two genuine differences).
Assisted-by: Claude:claude-opus-4-8:Claude Code
This commit adds a new parameter to PortablePdbWriter.WritePdb that
allows the caller to provide an implementation of IProgress to receive
status updates on the pdb generation process. Currently, the progress
reports include the number of files generated so far and the total
number of files.
Siegfried Pammer
Kirill Osenkov
Andrew Crawley (US - DIAGNOSTICS)