Fix for ilasm generation of malformed PDB files due to empty body methods (#46250)

* Fix malformed portable PDB generation for methods with empty body (#46124)

* Adding a test case for ilasm which verifies that the MethodDef and MethodDebugInformation tables have the same number of rows (#46124)

2 files changed, 13 insertions, 11 deletions

diff --git a/src/coreclr/ilasm/assem.cpp b/src/coreclr/ilasm/assem.cpp
index c8ef2691445..473ec42cda9 100644
--- a/src/coreclr/ilasm/assem.cpp
+++ b/src/coreclr/ilasm/assem.cpp
@@ -512,15 +512,6 @@ BOOL Assembler::EmitMethodBody(Method* pMethod, BinStr* pbsOut)
                 pFH = (COR_ILMETHOD_FAT*)(pMethod->m_pbsBody->ptr());
                 pFH->SetLocalVarSigTok(pMethod->m_LocalsSig);
             }
-            //--------------------------------------------------------------------------------
-            if(m_fGeneratePDB)
-            {
-                if (FAILED(m_pPortablePdbWriter->DefineSequencePoints(pMethod)))
-                    return FALSE;
-                if (FAILED(m_pPortablePdbWriter->DefineLocalScope(pMethod)))
-                    return FALSE;
-            } // end if(fIncludeDebugInfo)
-            //-----------------------------------------------------
 
             if(m_fFoldCode)
             {
@@ -597,6 +588,15 @@ BOOL Assembler::EmitMethodBody(Method* pMethod, BinStr* pbsOut)
             }
             m_pEmitter->SetRVA(pMethod->m_Tok,pMethod->m_headerOffset);
         }
+
+        if (m_fGeneratePDB)
+        {
+            if (FAILED(m_pPortablePdbWriter->DefineSequencePoints(pMethod)))
+                return FALSE;
+            if (FAILED(m_pPortablePdbWriter->DefineLocalScope(pMethod)))
+                return FALSE;
+        }
+
         return TRUE;
     }
     else return FALSE;
diff --git a/src/coreclr/ilasm/portable_pdb.cpp b/src/coreclr/ilasm/portable_pdb.cpp
index c7077d21c42..47a6111078e 100644
--- a/src/coreclr/ilasm/portable_pdb.cpp
+++ b/src/coreclr/ilasm/portable_pdb.cpp
@@ -223,6 +223,7 @@ HRESULT PortablePdbWriter::DefineSequencePoints(Method* method)
     LinePC* prevNonHiddenSeqPoint = NULL;
     LinePC* nextSeqPoint = NULL;
     BOOL isValid = TRUE;
+    BOOL hasEmptyMethodBody = method->m_LinePCList.COUNT() == 0;
 
     for (UINT32 i = 0; i < method->m_LinePCList.COUNT(); i++)
     {
@@ -304,9 +305,10 @@ HRESULT PortablePdbWriter::DefineSequencePoints(Method* method)
     }
 
     // finally define sequence points for the method
-    if (isValid && currSeqPoint != NULL)
+    if ((isValid && currSeqPoint != NULL) || hasEmptyMethodBody)
     {
-        ULONG documentRid = RidFromToken(currSeqPoint->pOwnerDocument->GetToken());
+        mdDocument document = hasEmptyMethodBody ? m_currentDocument->GetToken() : currSeqPoint->pOwnerDocument->GetToken();
+        ULONG documentRid = RidFromToken(document);
         hr = m_pdbEmitter->DefineSequencePoints(documentRid, blob->ptr(), blob->length());
     }