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Fix assertion failure in ILDasm with -METADATA=RAW flag - #122876

#122876
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AaronRobinsonMSFT merged 3 commits into
maindotnet/runtime:mainfrom
copilot/fix-assert-ildasm-metadata-rawdotnet/runtime:copilot/fix-assert-ildasm-metadata-rawCopy head branch name to clipboard
Jan 5, 2026
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Fix assertion failure in ILDasm with -METADATA=RAW flag#122876
AaronRobinsonMSFT merged 3 commits into
maindotnet/runtime:mainfrom
copilot/fix-assert-ildasm-metadata-rawdotnet/runtime:copilot/fix-assert-ildasm-metadata-rawCopy head branch name to clipboard

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Copilot AI commented Jan 5, 2026 •
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Description

ILDasm crashes with assertion failure when invoked with -METADATA=RAW:

ASSERT FAILED
    Expression: ARRAY_SIZE(g_szMapElementType) == ELEMENT_TYPE_MAX
    Location:   line 256 in src/coreclr/tools/metainfo/mdinfo.cpp

The g_szMapElementType and g_szMapUndecorateType arrays had 34 elements but ELEMENT_TYPE_MAX is 0x23 (35). Missing entry: ELEMENT_TYPE_CMOD_INTERNAL at index 0x22.

Added "CMOD_INTERNAL" to both arrays in mdinfo.cpp.

Customer Impact

ILDasm with -METADATA=RAW flag fails immediately on any assembly. Blocks metadata inspection workflows.

Regression

Yes. ELEMENT_TYPE_CMOD_INTERNAL was added to corhdr.h but corresponding array entries were not updated.

Testing

  • Built CoreCLR successfully
  • Verified ILDasm with -METADATA=RAW completes without assertion on test assembly

Risk

Low. Two-line fix adds missing array element to match enum definition. No logic changes.

Original prompt

This section details on the original issue you should resolve

<issue_title>Assert when passing -METADATA=RAW to ILDasm.</issue_title>
<issue_description>runtime/artifacts/bin/coreclr/osx.arm64.Debug/ildasm -ALL -METADATA=RAW Test.dll > out.txt
ASSERT FAILED
Expression: ARRAY_SIZE(g_szMapElementType) == ELEMENT_TYPE_MAX
Location: line 256 in .../runtime/src/coreclr/ildasm/../tools/metainfo/mdinfo.cpp
Function: MDInfo
Process: 36920
zsh: trace trap runtime/artifacts/bin/coreclr/osx.arm64.Debug/ildasm -ALL -METADATA=RAW</issue_description>

Comments on the Issue (you are @copilot in this section)

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Copilot AI and others added 2 commits January 5, 2026 15:14
@AaronRobinsonMSFT
Fix ELEMENT_TYPE_CMOD_INTERNAL missing from mdinfo arrays
d376d5b 
Co-authored-by: AaronRobinsonMSFT <30635565+AaronRobinsonMSFT@users.noreply.github.com>
@AaronRobinsonMSFT
Fix assert failure message location formatting
43b2610
@AaronRobinsonMSFT AaronRobinsonMSFT added this to the 11.0.0 milestone Jan 5, 2026
@AaronRobinsonMSFT
AaronRobinsonMSFT marked this pull request as ready for review January 5, 2026 15:21
Copilot AI review requested due to automatic review settings January 5, 2026 15:21
Copilot AI reviewed Jan 5, 2026
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Pull request overview

This PR fixes an assertion failure that occurs when running ILDasm with the -METADATA=RAW flag. The root cause was a size mismatch between the g_szMapElementType and g_szMapUndecorateType arrays (which had 34 elements) and the expected size ELEMENT_TYPE_MAX (which is 0x23 or 35 decimal). The missing element was ELEMENT_TYPE_CMOD_INTERNAL at index 0x22.

Key changes:

  • Added ELEMENT_TYPE_CMOD_INTERNAL entry to both mapping arrays in mdinfo.cpp to match the complete CorElementType enum
  • Modified assertion format in pal_assert.h to reorder filename and line number display

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File Description
src/coreclr/tools/metainfo/mdinfo.cpp Adds missing "CMOD_INTERNAL" entry at index 0x22 to both g_szMapElementType and g_szMapUndecorateType arrays, fixing the array size to match ELEMENT_TYPE_MAX (35 elements)
src/coreclr/pal/inc/pal_assert.h Reorders __FILE__ and __LINE__ parameters in assertion output format from "line %d in %s" to "%s:%d"

Comment thread src/coreclr/pal/inc/pal_assert.h
Copilot AI changed the title [WIP] Fix assert when passing -METADATA=RAW to ILDasm Fix assertion failure in ILDasm with -METADATA=RAW flag Jan 5, 2026
Copilot AI requested a review from AaronRobinsonMSFT January 5, 2026 15:28
@AaronRobinsonMSFT

AaronRobinsonMSFT commented Jan 5, 2026

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@jkoritzinsky Looks like we missed updating ILDasm when adding ELEMENT_TYPE_CMOD_INTERNAL in #106424.

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AaronRobinsonMSFT enabled auto-merge (squash) January 5, 2026 16:38
This was referenced Jan 5, 2026
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AaronRobinsonMSFT commented Jan 5, 2026

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/ba-g Unrelated

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AaronRobinsonMSFT merged commit 27a5c7d into main Jan 5, 2026
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AaronRobinsonMSFT deleted the copilot/fix-assert-ildasm-metadata-raw branch January 5, 2026 18:16
This was referenced Jan 9, 2026
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Reviewers

Copilot code review Copilot Copilot left review comments
@jkoritzinsky jkoritzinsky jkoritzinsky approved these changes
+1 more reviewer
@AaronRobinsonMSFT AaronRobinsonMSFT AaronRobinsonMSFT approved these changes
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area-ILTools-coreclr

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Milestone

11.0.0

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Successfully merging this pull request may close these issues.

Assert when passing -METADATA=RAW to ILDasm.

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