Only vbc's On Error lowering produces this filter; structured
Catch...When filters call SetProjectError and never reach it. Roslyn
emits it from a single code path with System.Exception as the type, and
legacy vbc output has the same shape, so there is no chain of unknown
conjuncts to walk. The transform runs before the expression transforms
canonicalize comparisons, so the filter still compares with cgt against
ldnull and cgt.un against zero: the ldnull comparison is fixed up first,
and MatchCompUnsignedZero accepts both the unsigned and canonical form.
Assisted-by: Claude:claude-opus-5:Claude Code
When an IfInstruction was created with resultType=bool, because only
values 0 or 1 are possible, then we need to preserve this property in
transforms -- otherwise the added correctness test would fail.
The Span<T>/ReadOnlySpan<T> initializer patterns replaced their call with an
array initializer block, so an array stood where a span was expected: the
enclosing leave and any call taking the result saw StackType.Obj against the
StackType.VT the span type demands. The block now ends in the implicit
conversion the C# compiler applies, which is the one shape besides a bare
ldloc that an array initializer may take; the expression builder keeps the
conversion out of the output but not out of the expression's type.
Naming that operator wants a method looked up by signature rather than by a
predicate over the type's members, so MetadataModule grows a ResolveMethod
overload for it, sharing its signature matching with the metadata path.
Assisted-by: Claude:claude-opus-5[1m]:Claude Code
GetPointerElementType existed because a pointer passing through a stack
slot could be typed IntPtr: ILReader replaced the slot type with
FindType(StackType) whenever the inferred type did not match the stack
type. With InferType() implemented on every ILInstruction that fallback
is gone (FlushExpressionStack now asserts the inferred type is
stack-accurate), so the target's inferred type is precise and the
definition chain no longer needs to be walked. Merged stack slots were
never recovered by the helper anyway (it required a single store).
Disabling the PointerType arm makes the uint*/byte* deconstruction
fixtures fail, so the sign-agnostic stobj.Type fallback remains guarded.
Assisted-by: Claude:claude-fable-5:Claude Code
Change InferType() to an abstract method and implement for every ILInstruction.
With this change, we now always have enough information to create a variable of an appropriate type to store the result of evaluating the instruction.
This previously was not the case for instructions producing "other value type", for which the stacktype-based fallback incorrectly produced `object`.
Invariants that involve types (stack type of a variable against its IType,
the element type of an array access, the operand types of a comparison)
need a type system to resolve them against, and the only correct one is the
type system the instruction tree was decoded with. Until now CheckInvariant
took only the phase, so such a check had no compilation to use:
DeconstructInstruction.CheckInvariant called IsAssignment with a null type
system, which only held up because the targets it sees are ldloc, whose
InferType never touches the compilation; a ldflda-wrapped or pointer target
would have failed inside the invariant instead of reporting a violation.
Every call site already has that type system in scope: the ILReader's
compilation, the ILTransformContext of the running transform, or the
decompiler's own IDecompilerTypeSystem. It is now passed explicitly and the
base implementation asserts it is present, so a future invariant can rely
on it without re-plumbing the callers.
Assisted-by: Claude:claude-fable-5:Claude Code
A dynamic call site that names a type passes typeof(T) as its target. When
a later argument contains control flow, the compiler stores that typeof in
a temporary. ILInlining does not undo this: it inlines a store only into
the immediately following instruction, so an intervening statement leaves
the typeof behind, and the expression builder printed the temporary instead
of the type. Substituting the typeof back into the target slot is not an
option either, because a call there has side effects and blocks inlining of
the remaining arguments.
The type is therefore stored on the instruction. Object creation already
did this, but kept the field private, so the expression builder re-derived
the type from the target argument and failed on the spilled form. Member
invocation gets the same field. Both drop the target from Arguments, so the
dead-argument handling removes the store; ArgumentInfo keeps its entry for
the target, because the invocation symbol is built from it.
The type of an object creation is not nullable: the transform returns
before constructing the instruction when it cannot match the typeof, and
substitutes the unknown type otherwise. An unresolvable type therefore
reaches the expression builder as the unresolved type it is, and prints as
`?` like any other, rather than being indistinguishable from a missing one.
Those two are also the only binder method kinds that ever see
CSharpArgumentInfoFlags.IsStaticType. Every other way of naming a type as
the receiver binds statically and leaves only a conversion of the dynamic
operand behind.
Assisted-by: Claude:claude-opus-5[1m]:Claude Code
Two extra pieces of state existed to reconstruct what the stepper already
records: which member a halt belongs to. The step the limit stopped on answers
it, except on a member's opening step, which is where the previous member's
state ends - and there the last step actually recorded answers it instead.
IL group openers gain an anchor so their position resolves. The member opener
deliberately keeps none: anchoring it to the member the pipeline is about to
start is exactly the misattribution the fallback exists to avoid.
Assisted-by: Claude:claude-opus-5[1m]:Claude Code
There's an additional local variable when decompiling the non-optimized code; and explicitly putting that variable
into the test case just makes it fail due to yet another additional variable.
'this' and 'base' both read the 'this' parameter of the function being
decompiled, but their resolve result did not say so: consumers that key on
ILVariableResolveResult (local-reference output, highlighting, hover) could
not connect the keyword to the variable, and the qualified/unqualified
spellings of the same access carried differently shaped annotations.
The resolver has no ILFunction and thus no variable to put into a
ThisResolveResult, so it stops synthesizing one: LookInCurrentType looks
the name up against the (self-parameterized) current type, which grants
the same protected access, and the annotation of an unqualified field
access is built from the translated target instead. ResolveThisReference
and ResolveBaseReference had no callers left and are removed.
Assisted-by: Claude:claude-fable-5:Claude Code
Deconstruction into a pointer target ((*p, value) = tuple;) stayed an
explicit Deconstruct call: a store through a pointer (or through a target
whose pointer type got erased in a stack slot) does not infer a
ByReferenceType, so IsAssignment reported an unknown expected type and the
transform's conversion check rejected the assignment. The type of the store
itself is just as precise, so use it as the expected type.
Of the three IsAssignment call sites only the transform's MatchAssignment
consumes the expected type; CheckInvariant and GetAssignmentIndex discard
it, so this widens what the transform accepts without weakening the
invariant check.
Assisted-by: Claude:claude-opus-5:Claude Code
The events introduced in #2519 timed only the five per-entity DoDecompile
overloads, allocated a Stopwatch and the member's FullName even when no
trace session was attached, and reported whole milliseconds, which rounds
almost every member to zero. Flat one-shot events also gave PerfView and
dotnet-trace no way to show durations or nesting, and the actually
expensive stages (type system initialization, assembly resolution probing,
the IL/AST transform pipelines, whole-project decompilation) were not
instrumented at all.
Start/Stop event pairs let trace viewers derive duration and nesting from
event timestamps, keywords let a session enable only the areas of
interest, and every call site is gated on IsEnabled() so tracing costs a
branch when disabled. Per-transform events are Verbose because of their
volume; unlike the STEP/Stepper mechanism they work in Release builds.
EventSource is in-box for netstandard2.0 and flows over both ETW and
EventPipe, so this stays cross-platform with no new dependency.
Assisted-by: Claude:claude-fable-5:Claude Code
Backfills the standard MIT X11 header on hand-written files that never
got one, attributing each to its first-commit author and year from git
history. Code vendored from dotnet/runtime and Humanizr/Humanizer gets
its origin's license lines and a provenance note instead. Generated
files (Resources.Designer.cs, the version-info template), tool-managed
suppression files, and BAML test-case fixtures intentionally stay
header-less.
Assisted-by: Claude:claude-fable-5:Claude Code
The debug-step node bracket (MarkNodeStart/try/finally/MarkNodeEnd) was copied
into every hand-written WriteTo override and re-emitted by the T4 generator, so
a newly added instruction could silently omit it and lose step highlighting with
no compile error or test failure. Seal WriteTo on ILInstruction to apply the
bracket once and delegate to a new abstract WriteToCore; move every override
(hand-written and generated) to WriteToCore without the wrapper. Rendered output
is unchanged -- the marks are no-ops unless the output tracks nodes.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The C# debug-steps view highlights and centers the exact AST node a
transform changed; the ILAst view already had the step tree and
replay-at-step but produced no highlight. Bring it to parity.
IL rendering has no token-writer seam like the C# output visitor, so
per-instruction text spans are recorded by bracketing
ILInstruction.WriteTo via a new INodeTrackingOutput. The dominant
inst.ReplaceWith(newInst) transform pattern detaches the instruction
passed to Step, so ILTransformContext gains EndStep to record the
produced instruction; Stepper additionally records the position's
ancestor chain as fallback candidates before the step-limit throw, so
the "show state before" view -- which halts at the selected step --
still resolves to a surviving ancestor (ultimately the ILFunction).
The highlight-range resolver is shared with the C# language.
Assisted-by: Claude:claude-opus-4-8:Claude Code
TokenRole was a printer-side descriptor whose only jobs were holding a token's
text and giving the writers an identity to single out specific tokens. The text
becomes plain const strings on the nodes, and the few identity checks are
reexpressed as node-stack context: interpolation braces are recognized by an
Interpolation on the writer's stack, record class versus struct coloring keys
off TypeDeclaration.ClassType, and the accessor/this/base/override cases fall
out of the surrounding node. WriteKeyword/WriteToken drop the descriptor
parameter. The constants are named for what the token is: a keyword, a symbol
token, or a modifier.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The C# 9 IntPtr / UIntPtr guard in IsBinaryCompatibleWithType read
type.Kind is not TypeKind.NInt or TypeKind.NUInt
which parses as `(is not NInt) or (is NUInt)` — true unless
Kind == NInt. The intent (per the surrounding comment "but not nint
or C# 11 IntPtr") is "Kind is neither NInt nor NUInt", which needs
parentheses around the alternation:
type.Kind is not (TypeKind.NInt or TypeKind.NUInt)
Effect: when Kind == NUInt the branch no longer mistakenly applies
the C# 9 IntPtr-only restrictions (suppressing compound assignment
without nint, disallowing shifts).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This way we avoid having to extract later, as we will never inline if the `isinst` argument if this could result in it being unrepresentable in C#.
This commit also refactors inlining restrictions to avoid requiring special cases in ILInlining itself.
But when making this change, I discovered that this broke our pattern-matching tests, and that the weird IL with double `isinst` is indeed generated by the C# compiler for `if (genericParam is StringComparison.Ordinal)` style code. So instead we also allow `isinst` with a `box(expr-without-side-effects)` argument to be represented with the `expr is T ? (T)expr : null` emulation.
Siegfried Pammer
Daniel Grunwald
Christoph Wille
Peter Crabtree