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Fix IsPortableCodeView when rewriting assembly. #688

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Fix IsPortableCodeView when rewriting assembly. #688

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10 changes: 9 additions & 1 deletion src/Microsoft.DotNet.CilStrip.Sources/src/Mono.Cecil.Binary/CopyImageVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,8 +53,16 @@ public override void VisitDebugHeader (DebugHeader dbgHeader)
dbgHeader.Age = old.Age;
dbgHeader.Characteristics = old.Characteristics;
dbgHeader.FileName = old.FileName;
dbgHeader.MajorVersion = old.MajorVersion;
dbgHeader.MinorVersion = old.MinorVersion;
dbgHeader.Signature = old.Signature;
dbgHeader.TimeDateStamp = ImageInitializer.TimeDateStampFromEpoch();
// Portable PDBs (CodeView MinorVersion magic 0x504D) encode a content-derived stamp that
// is part of the PDB identity. Preserve it so the rewritten image keeps matching its
// unmodified PDB (IsPortableCodeView stays true and symbolication still works). Other

@akoeplinger akoeplinger Jul 30, 2026

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@lateralusX so we don't touch the PDB at all in ILStrip? I think we do in ILLink

@lateralusX lateralusX Jul 31, 2026 •
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ILStrip don't touch the PDB it's just removing things from the assembly. ILLink rewrites the PDB (since it drops tokens and metadata), but the timestamp is not a timestamp but a hash for portable PDB's, it must be synced with the updated PDB in the updated assembly. ILLink goes through another cecil that handle that part correct, it recreates the new PDB and assembly together making sure fields align and since the issue only reproduce when running ILStrip, not ILLink, this is an ILStrip isolated issue.

// debug entry kinds retain the historical behavior of a freshly generated stamp.
dbgHeader.TimeDateStamp = old.MinorVersion == 0x504D
? old.TimeDateStamp
: ImageInitializer.TimeDateStampFromEpoch();
dbgHeader.Type = old.Type;
}

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