Free temporary enums on failure (#50471)

* Free temporary enums on failure

* PR feedback

4 files changed, 107 insertions, 85 deletions

diff --git a/src/coreclr/md/compiler/assemblymd.cpp b/src/coreclr/md/compiler/assemblymd.cpp
index d778c636722..759c7dc69d8 100644
--- a/src/coreclr/md/compiler/assemblymd.cpp
+++ b/src/coreclr/md/compiler/assemblymd.cpp
@@ -444,7 +444,7 @@ STDMETHODIMP RegMeta::EnumExportedTypes(           // S_OK or error
     BEGIN_ENTRYPOINT_NOTHROW;
 
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
-    HENUMInternal       *pEnum;
+    HENUMInternal       *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumExportedTypes(%#08x, %#08x, %#08x, %#08x)\n",
         phEnum, rExportedTypes, cMax, pcTokens));
@@ -488,14 +488,14 @@ STDMETHODIMP RegMeta::EnumExportedTypes(           // S_OK or error
 
         // set the output parameter.
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
-    else
-        pEnum = *ppmdEnum;
 
     // we can only fill the minimum of what the caller asked for or what we have left.
-    IfFailGo(HENUMInternal::EnumWithCount(pEnum, cMax, rExportedTypes, pcTokens));
+    IfFailGo(HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rExportedTypes, pcTokens));
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumExportedTypes);
     END_ENTRYPOINT_NOTHROW;
diff --git a/src/coreclr/md/compiler/custattr_import.cpp b/src/coreclr/md/compiler/custattr_import.cpp
index cc38921992e..ec05e2663df 100644
--- a/src/coreclr/md/compiler/custattr_import.cpp
+++ b/src/coreclr/md/compiler/custattr_import.cpp
@@ -108,7 +108,7 @@ STDMETHODIMP RegMeta::EnumCustomAttributes(
     HENUMInternal   **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     RID             ridStart;
     RID             ridEnd;
-    HENUMInternal   *pEnum = *ppmdEnum;
+    HENUMInternal   *pEnum = NULL;
     CustomAttributeRec  *pRec;
     ULONG           index;
 
@@ -117,7 +117,7 @@ STDMETHODIMP RegMeta::EnumCustomAttributes(
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -220,13 +220,15 @@ STDMETHODIMP RegMeta::EnumCustomAttributes(
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rCustomAttributes, pcCustomAttributes);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rCustomAttributes, pcCustomAttributes);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumCustomAttributes);
     END_ENTRYPOINT_NOTHROW;
diff --git a/src/coreclr/md/compiler/import.cpp b/src/coreclr/md/compiler/import.cpp
index c0abc8f7f63..6559b2b31e9 100644
--- a/src/coreclr/md/compiler/import.cpp
+++ b/src/coreclr/md/compiler/import.cpp
@@ -44,7 +44,7 @@ STDMETHODIMP RegMeta::EnumMembers(            // S_OK, S_FALSE, or error.
     RID             index;
     RID             indexField;
     TypeDefRec      *pRec;
-    HENUMInternal   *pEnum = *ppmdEnum;
+    HENUMInternal   *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumMembers(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, cl, rMembers, cMax, pcTokens));
@@ -52,7 +52,7 @@ STDMETHODIMP RegMeta::EnumMembers(            // S_OK, S_FALSE, or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -95,13 +95,15 @@ STDMETHODIMP RegMeta::EnumMembers(            // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMembers, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMembers, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMembers);
 
@@ -132,7 +134,7 @@ STDMETHODIMP RegMeta::EnumMembersWithName(    // S_OK, S_FALSE, or error.
     TypeDefRec          *pRec;
     MethodRec           *pMethod;
     FieldRec            *pField;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     LPUTF8              szNameUtf8;
     UTF8STR(szName, szNameUtf8);
     LPCUTF8             szNameUtf8Tmp;
@@ -143,7 +145,7 @@ STDMETHODIMP RegMeta::EnumMembersWithName(    // S_OK, S_FALSE, or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -214,13 +216,15 @@ STDMETHODIMP RegMeta::EnumMembersWithName(    // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMembers, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMembers, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMembersWithName);
     END_ENTRYPOINT_NOTHROW;
@@ -246,7 +250,7 @@ STDMETHODIMP RegMeta::EnumMethods(
     RID                 ridStart;
     RID                 ridEnd;
     TypeDefRec          *pRec;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumMethods(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, td, rMethods, cMax, pcTokens));
@@ -256,7 +260,7 @@ STDMETHODIMP RegMeta::EnumMethods(
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -308,13 +312,15 @@ STDMETHODIMP RegMeta::EnumMethods(
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMethods, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMethods, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMethods);
     END_ENTRYPOINT_NOTHROW;
@@ -346,7 +352,7 @@ STDMETHODIMP RegMeta::EnumMethodsWithName(    // S_OK, S_FALSE, or error.
     RID                 index;
     TypeDefRec          *pRec;
     MethodRec           *pMethod;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     LPUTF8              szNameUtf8;
     UTF8STR(szName, szNameUtf8);
     LPCUTF8             szNameUtf8Tmp;
@@ -360,7 +366,7 @@ STDMETHODIMP RegMeta::EnumMethodsWithName(    // S_OK, S_FALSE, or error.
     LOCKREAD();
 
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -410,13 +416,15 @@ STDMETHODIMP RegMeta::EnumMethodsWithName(    // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMethods, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMethods, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMethodsWithName);
     END_ENTRYPOINT_NOTHROW;
@@ -445,7 +453,7 @@ RegMeta::EnumFields(
     RID             ridStart;
     RID             ridEnd;
     TypeDefRec     *pRec;
-    HENUMInternal  *pEnum = *ppmdEnum;
+    HENUMInternal  *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumFields(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, td, rFields, cMax, pcTokens));
@@ -453,7 +461,7 @@ RegMeta::EnumFields(
     START_MD_PERF();
     LOCKREAD();
 
-    if (pEnum == NULL)
+    if (*ppmdEnum == NULL)
     {
         // instantiating a new ENUM
         CMiniMdRW *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -505,13 +513,15 @@ RegMeta::EnumFields(
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rFields, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rFields, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumFields);
     END_ENTRYPOINT_NOTHROW;
@@ -542,7 +552,7 @@ STDMETHODIMP RegMeta::EnumFieldsWithName(     // S_OK, S_FALSE, or error.
     ULONG               index;
     TypeDefRec          *pRec;
     FieldRec            *pField;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     LPUTF8              szNameUtf8;
     UTF8STR(szName, szNameUtf8);
     LPCUTF8             szNameUtf8Tmp;
@@ -555,7 +565,7 @@ STDMETHODIMP RegMeta::EnumFieldsWithName(     // S_OK, S_FALSE, or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -604,13 +614,15 @@ STDMETHODIMP RegMeta::EnumFieldsWithName(     // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rFields, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rFields, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumFieldsWithName);
     END_ENTRYPOINT_NOTHROW;
@@ -637,7 +649,7 @@ STDMETHODIMP RegMeta::EnumParams(             // S_OK, S_FALSE, or error.
     RID                 ridStart;
     RID                 ridEnd;
     MethodRec           *pRec;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumParams(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, mb, rParams, cMax, pcTokens));
@@ -645,7 +657,7 @@ STDMETHODIMP RegMeta::EnumParams(             // S_OK, S_FALSE, or error.
     LOCKREAD();
 
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -674,13 +686,15 @@ STDMETHODIMP RegMeta::EnumParams(             // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rParams, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rParams, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumParams);
     END_ENTRYPOINT_NOTHROW;
@@ -708,7 +722,7 @@ STDMETHODIMP RegMeta::EnumMemberRefs(         // S_OK, S_FALSE, or error.
     ULONG               ridEnd;
     ULONG               index;
     MemberRefRec        *pRec;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumMemberRefs(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, tkParent, rMemberRefs, cMax, pcTokens));
@@ -718,7 +732,7 @@ STDMETHODIMP RegMeta::EnumMemberRefs(         // S_OK, S_FALSE, or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -748,13 +762,15 @@ STDMETHODIMP RegMeta::EnumMemberRefs(         // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        *ppmdEnum = 0;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMemberRefs, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMemberRefs, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMemberRefs);
 
@@ -781,7 +797,7 @@ STDMETHODIMP RegMeta::EnumMethodImpls(        // S_OK, S_FALSE, or error
 
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     MethodImplRec       *pRec;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     HENUMInternal hEnum;
 
 
@@ -795,7 +811,7 @@ STDMETHODIMP RegMeta::EnumMethodImpls(        // S_OK, S_FALSE, or error
 
     HENUMInternal::ZeroEnum(&hEnum);
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -824,13 +840,15 @@ STDMETHODIMP RegMeta::EnumMethodImpls(        // S_OK, S_FALSE, or error
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMethodBody, rMethodDecl, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMethodBody, rMethodDecl, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
     HENUMInternal::ClearEnum(&hEnum);
 
     STOP_MD_PERF(EnumMethodImpls);
@@ -861,7 +879,7 @@ STDMETHODIMP RegMeta::EnumPermissionSets(     // S_OK, S_FALSE, or error.
     RID                 ridEnd;
     RID                 index;
     DeclSecurityRec     *pRec;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     bool                fCompareParent = false;
     mdToken             typ = TypeFromToken(tk);
     mdToken             tkParent;
@@ -872,7 +890,7 @@ STDMETHODIMP RegMeta::EnumPermissionSets(     // S_OK, S_FALSE, or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // Does this token type even have security?
         if (tk != 0 &&
@@ -943,13 +961,15 @@ STDMETHODIMP RegMeta::EnumPermissionSets(     // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rPermission, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rPermission, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumPermissionSets);
     END_ENTRYPOINT_NOTHROW;
@@ -1317,7 +1337,7 @@ STDMETHODIMP RegMeta::EnumProperties(         // S_OK, S_FALSE, or error.
     RID                 ridStart = 0;
     RID                 ridEnd = 0;
     RID                 ridMax = 0;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumProperties(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, td, rProperties, cMax, pcProperties));
@@ -1336,7 +1356,7 @@ STDMETHODIMP RegMeta::EnumProperties(         // S_OK, S_FALSE, or error.
     _ASSERTE(TypeFromToken(td) == mdtTypeDef);
 
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -1391,13 +1411,15 @@ STDMETHODIMP RegMeta::EnumProperties(         // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rProperties, pcProperties);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rProperties, pcProperties);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
 
     STOP_MD_PERF(EnumProperties);
@@ -1426,7 +1448,7 @@ STDMETHODIMP RegMeta::EnumEvents(              // S_OK, S_FALSE, or error.
     RID             ridStart = 0;
     RID             ridEnd = 0;
     RID             ridMax = 0;
-    HENUMInternal   *pEnum = *ppmdEnum;
+    HENUMInternal   *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumEvents(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, td, rEvents,  cMax, pcEvents));
@@ -1437,7 +1459,7 @@ STDMETHODIMP RegMeta::EnumEvents(              // S_OK, S_FALSE, or error.
     _ASSERTE(TypeFromToken(td) == mdtTypeDef);
 
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -1492,14 +1514,15 @@ STDMETHODIMP RegMeta::EnumEvents(              // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rEvents, pcEvents);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rEvents, pcEvents);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
-
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumEvents);
     END_ENTRYPOINT_NOTHROW;
@@ -1638,7 +1661,7 @@ STDMETHODIMP RegMeta::EnumMethodSemantics(    // S_OK, S_FALSE, or error.
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     ULONG               ridEnd;
     ULONG               index;
-    HENUMInternal       *pEnum = *ppmdEnum;
+    HENUMInternal       *pEnum = NULL;
     MethodSemanticsRec  *pRec;
 
     LOG((LOGMD, "MD RegMeta::EnumMethodSemantics(0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
@@ -1648,7 +1671,7 @@ STDMETHODIMP RegMeta::EnumMethodSemantics(    // S_OK, S_FALSE, or error.
     LOCKREAD();
 
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         CMiniMdRW       *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -1670,14 +1693,15 @@ STDMETHODIMP RegMeta::EnumMethodSemantics(    // S_OK, S_FALSE, or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rEventProp, pcEventProp);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rEventProp, pcEventProp);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
-
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumMethodSemantics);
     END_ENTRYPOINT_NOTHROW;
@@ -2298,7 +2322,7 @@ STDMETHODIMP RegMeta::EnumUnresolvedMethods(  // S_OK or error.
     uint32_t         index;              // For counting methods on a TypeDef.
     uint32_t         indexTypeDef;       // For counting TypeDefs.
     bool             bIsInterface;       // Is a given TypeDef an interface?
-    HENUMInternal *  pEnum = *ppmdEnum; // Enum we're working with.
+    HENUMInternal *  pEnum = NULL; // Enum we're working with.
     CMiniMdRW *      pMiniMd = &(m_pStgdb->m_MiniMd);
 
     LOG((LOGMD, "MD RegMeta::EnumUnresolvedMethods(0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
@@ -2310,7 +2334,7 @@ STDMETHODIMP RegMeta::EnumUnresolvedMethods(  // S_OK or error.
     // same time. Ref to Def map may be calculated incorrectly.
     LOCKWRITE();
 
-    if ( pEnum == 0 )
+    if ( *ppmdEnum == 0 )
     {
         // instantiating a new ENUM
         MethodRec       *pMethodRec;
@@ -2403,13 +2427,15 @@ STDMETHODIMP RegMeta::EnumUnresolvedMethods(  // S_OK or error.
 
         // set the output parameter
         *ppmdEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rMethods, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rMethods, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumUnresolvedMethods);
     END_ENTRYPOINT_NOTHROW;
@@ -2664,7 +2690,7 @@ STDMETHODIMP RegMeta::EnumUserStrings(        // S_OK or error.
     BEGIN_ENTRYPOINT_NOTHROW;
 
     HENUMInternal **ppEnum = reinterpret_cast<HENUMInternal **> (phEnum);
-    HENUMInternal  *pEnum = *ppEnum;
+    HENUMInternal  *pEnum = NULL;
 
     LOG((LOGMD, "MD RegMeta::EnumUserStrings(0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
         phEnum, rStrings, cmax, pcStrings));
@@ -2672,7 +2698,7 @@ STDMETHODIMP RegMeta::EnumUserStrings(        // S_OK or error.
     START_MD_PERF();
     LOCKREAD();
 
-    if (pEnum == NULL)
+    if (*ppEnum == NULL)
     {
         // instantiating a new ENUM.
         CMiniMdRW *pMiniMd = &(m_pStgdb->m_MiniMd);
@@ -2712,14 +2738,15 @@ STDMETHODIMP RegMeta::EnumUserStrings(        // S_OK or error.
 
         // set the output parameter.
         *ppEnum = pEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer.
-    hr = HENUMInternal::EnumWithCount(pEnum, cmax, rStrings, pcStrings);
+    hr = HENUMInternal::EnumWithCount(*ppEnum, cmax, rStrings, pcStrings);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppEnum);
-
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumUserStrings);
     END_ENTRYPOINT_NOTHROW;
diff --git a/src/coreclr/md/compiler/regmeta_import.cpp b/src/coreclr/md/compiler/regmeta_import.cpp
index a305c1dd286..e93cc2aeeb6 100644
--- a/src/coreclr/md/compiler/regmeta_import.cpp
+++ b/src/coreclr/md/compiler/regmeta_import.cpp
@@ -175,7 +175,7 @@ STDMETHODIMP RegMeta::EnumTypeDefs(
     BEGIN_ENTRYPOINT_NOTHROW;
 
     HENUMInternal   **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
-    HENUMInternal   *pEnum;
+    HENUMInternal   *pEnum = NULL;
 
     LOG((LOGMD, "RegMeta::EnumTypeDefs(0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
             phEnum, rTypeDefs, cMax, pcTypeDefs));
@@ -219,17 +219,15 @@ STDMETHODIMP RegMeta::EnumTypeDefs(
 
         // set the output parameter
         *ppmdEnum = pEnum;
-    }
-    else
-    {
-        pEnum = *ppmdEnum;
+        pEnum = NULL;
     }
 
     // we can only fill the minimun of what caller asked for or what we have left
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rTypeDefs, pcTypeDefs);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rTypeDefs, pcTypeDefs);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumTypeDefs);
 
@@ -255,7 +253,7 @@ STDMETHODIMP RegMeta::EnumInterfaceImpls(
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     RID                 ridStart;
     RID                 ridEnd;
-    HENUMInternal       *pEnum;
+    HENUMInternal       *pEnum = NULL;
     InterfaceImplRec    *pRec;
     RID                 index;
 
@@ -298,17 +296,15 @@ STDMETHODIMP RegMeta::EnumInterfaceImpls(
 
         // set the output parameter
         *ppmdEnum = pEnum;
-    }
-    else
-    {
-        pEnum = *ppmdEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMax, rImpls, pcImpls);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMax, rImpls, pcImpls);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
 
     STOP_MD_PERF(EnumInterfaceImpls);
 
@@ -327,7 +323,7 @@ STDMETHODIMP RegMeta::EnumGenericParams(HCORENUM *phEnum, mdToken tkOwner,
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     RID                 ridStart;
     RID                 ridEnd;
-    HENUMInternal       *pEnum;
+    HENUMInternal       *pEnum = NULL;
     GenericParamRec     *pRec;
     RID                 index;
     CMiniMdRW           *pMiniMd = NULL;
@@ -394,17 +390,16 @@ STDMETHODIMP RegMeta::EnumGenericParams(HCORENUM *phEnum, mdToken tkOwner,
 
         // set the output parameter
         *ppmdEnum = pEnum;
-    }
-    else
-    {
-        pEnum = *ppmdEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMaxTokens, rTokens, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMaxTokens, rTokens, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
+
     STOP_MD_PERF(EnumGenericPars);
     END_ENTRYPOINT_NOTHROW;
 
@@ -425,7 +420,7 @@ STDMETHODIMP RegMeta::EnumMethodSpecs(
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     RID                 ridStart;
     RID                 ridEnd;
-    HENUMInternal       *pEnum;
+    HENUMInternal       *pEnum = NULL;
     MethodSpecRec       *pRec;
     RID                 index;
     CMiniMdRW       *pMiniMd = NULL;
@@ -499,17 +494,16 @@ STDMETHODIMP RegMeta::EnumMethodSpecs(
         }
         // set the output parameter
         *ppmdEnum = pEnum;
-    }
-    else
-    {
-        pEnum = *ppmdEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMaxTokens, rTokens, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMaxTokens, rTokens, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
+
     STOP_MD_PERF(EnumMethodSpecs);
     END_ENTRYPOINT_NOTHROW;
 
@@ -530,7 +524,7 @@ STDMETHODIMP RegMeta::EnumGenericParamConstraints(
     HENUMInternal       **ppmdEnum = reinterpret_cast<HENUMInternal **> (phEnum);
     RID                 ridStart;
     RID                 ridEnd;
-    HENUMInternal       *pEnum;
+    HENUMInternal       *pEnum = NULL;
     GenericParamConstraintRec     *pRec;
     RID                 index;
     CMiniMdRW       *pMiniMd = NULL;
@@ -588,17 +582,16 @@ STDMETHODIMP RegMeta::EnumGenericParamConstraints(
 
         // set the output parameter
         *ppmdEnum = pEnum;
-    }
-    else
-    {
-        pEnum = *ppmdEnum;
+        pEnum = NULL;
     }
 
     // fill the output token buffer
-    hr = HENUMInternal::EnumWithCount(pEnum, cMaxTokens, rTokens, pcTokens);
+    hr = HENUMInternal::EnumWithCount(*ppmdEnum, cMaxTokens, rTokens, pcTokens);
 
 ErrExit:
     HENUMInternal::DestroyEnumIfEmpty(ppmdEnum);
+    HENUMInternal::DestroyEnum(pEnum);
+
     STOP_MD_PERF(EnumGenericParamConstraints);
     END_ENTRYPOINT_NOTHROW;