Bug 1487082 - Resolve potential for build bustage regarding bad implicit conversion constructors

* Part 1: make conversion CTORs explicit.
  Minor tweaks to conform with new(ish) static analysis rule which flags up implicit single-argument conversion constructors.
* Part 2: fix a couple of double-mRefCnt declaration errors.
* Part 3: Fix unsafe use of NS_ConvertASCIItoUTF16().

Tag #1273

50 files changed, 61 insertions, 59 deletions

diff --git a/mailnews/addrbook/src/nsAbBSDirectory.cpp b/mailnews/addrbook/src/nsAbBSDirectory.cpp
index 0d018bbda..7ebe67845 100644
--- a/mailnews/addrbook/src/nsAbBSDirectory.cpp
+++ b/mailnews/addrbook/src/nsAbBSDirectory.cpp
@@ -242,7 +242,7 @@ NS_IMETHODIMP nsAbBSDirectory::DeleteDirectory(nsIAbDirectory *directory)
 
   struct GetDirectories
   {
-    GetDirectories(DIR_Server* aServer) : mServer(aServer) { }
+    explicit GetDirectories(DIR_Server* aServer) : mServer(aServer) { }
 
     nsCOMArray<nsIAbDirectory> directories;
     DIR_Server* mServer;
diff --git a/mailnews/addrbook/src/nsAbMDBDirProperty.h b/mailnews/addrbook/src/nsAbMDBDirProperty.h
index 3ee90d17e..fce4db297 100644
--- a/mailnews/addrbook/src/nsAbMDBDirProperty.h
+++ b/mailnews/addrbook/src/nsAbMDBDirProperty.h
@@ -28,7 +28,7 @@ class nsAbMDBDirProperty: public nsIAbMDBDirectory, public nsAbDirProperty
 public: 
 	nsAbMDBDirProperty(void);
 
-	NS_DECL_ISUPPORTS
+	NS_DECL_ISUPPORTS_INHERITED
 	NS_DECL_NSIABMDBDIRECTORY
 
 protected:
diff --git a/mailnews/addrbook/src/nsAbUtils.h b/mailnews/addrbook/src/nsAbUtils.h
index d6b8915e0..c50ba4d0d 100644
--- a/mailnews/addrbook/src/nsAbUtils.h
+++ b/mailnews/addrbook/src/nsAbUtils.h
@@ -15,7 +15,7 @@
 class CharPtrArrayGuard
 {
 public:
-    CharPtrArrayGuard (bool freeElements = true) :
+    explicit CharPtrArrayGuard (bool freeElements = true) :
         mFreeElements (freeElements),
         mArray (0),
         mSize (0)
@@ -80,7 +80,7 @@ private:
 class PRUnicharPtrArrayGuard
 {
 public:
-    PRUnicharPtrArrayGuard (bool freeElements = true) :
+    explicit PRUnicharPtrArrayGuard (bool freeElements = true) :
         mFreeElements (freeElements),
         mArray (0),
         mSize (0)
diff --git a/mailnews/addrbook/src/nsAddrDatabase.cpp b/mailnews/addrbook/src/nsAddrDatabase.cpp
index ea29ba8af..9b1450b94 100644
--- a/mailnews/addrbook/src/nsAddrDatabase.cpp
+++ b/mailnews/addrbook/src/nsAddrDatabase.cpp
@@ -2507,7 +2507,7 @@ public:
     NS_DECL_NSIADDRDBLISTENER
     // nsAddrDBEnumerator methods:
 
-    nsAddrDBEnumerator(nsAddrDatabase* aDb);
+    explicit nsAddrDBEnumerator(nsAddrDatabase* aDb);
     void Clear();
 protected:
     virtual ~nsAddrDBEnumerator();
diff --git a/mailnews/base/search/public/nsMsgResultElement.h b/mailnews/base/search/public/nsMsgResultElement.h
index 384436299..f8cdf4404 100644
--- a/mailnews/base/search/public/nsMsgResultElement.h
+++ b/mailnews/base/search/public/nsMsgResultElement.h
@@ -20,7 +20,7 @@
 class nsMsgResultElement
 {
 public:
-  nsMsgResultElement (nsIMsgSearchAdapter *);
+  explicit nsMsgResultElement (nsIMsgSearchAdapter *);
   virtual ~nsMsgResultElement ();
 
   static nsresult AssignValues (nsIMsgSearchValue *src, nsMsgSearchValue *dst);
diff --git a/mailnews/base/search/public/nsMsgSearchBoolExpression.h b/mailnews/base/search/public/nsMsgSearchBoolExpression.h
index c65e5c24a..9c6a9c8d8 100644
--- a/mailnews/base/search/public/nsMsgSearchBoolExpression.h
+++ b/mailnews/base/search/public/nsMsgSearchBoolExpression.h
@@ -41,7 +41,7 @@ class nsMsgSearchBoolExpression
 public:
 
   // create a leaf node expression
-  nsMsgSearchBoolExpression(nsIMsgSearchTerm * aNewTerm,
+  explicit nsMsgSearchBoolExpression(nsIMsgSearchTerm * aNewTerm,
                               char * aEncodingString = NULL);
 
   // create a non-leaf node expression containing 2 expressions
diff --git a/mailnews/base/search/src/nsMsgSearchValue.h b/mailnews/base/search/src/nsMsgSearchValue.h
index ef50ad1ed..3d08d27fa 100644
--- a/mailnews/base/search/src/nsMsgSearchValue.h
+++ b/mailnews/base/search/src/nsMsgSearchValue.h
@@ -11,7 +11,7 @@
 
 class nsMsgSearchValueImpl : public nsIMsgSearchValue {
   public:
-    nsMsgSearchValueImpl(nsMsgSearchValue *aInitialValue);
+    explicit nsMsgSearchValueImpl(nsMsgSearchValue *aInitialValue);
 
     NS_DECL_ISUPPORTS
     NS_DECL_NSIMSGSEARCHVALUE
diff --git a/mailnews/base/src/nsMailDirProvider.h b/mailnews/base/src/nsMailDirProvider.h
index d12876d89..613551a79 100644
--- a/mailnews/base/src/nsMailDirProvider.h
+++ b/mailnews/base/src/nsMailDirProvider.h
@@ -29,7 +29,7 @@ private:
     NS_DECL_ISUPPORTS
     NS_DECL_NSISIMPLEENUMERATOR
 
-    AppendingEnumerator(nsISimpleEnumerator* aBase);
+    explicit AppendingEnumerator(nsISimpleEnumerator* aBase);
 
   private:
     ~AppendingEnumerator() {}
diff --git a/mailnews/base/src/nsMsgCopyService.h b/mailnews/base/src/nsMsgCopyService.h
index dfb9acc7a..8df9ccff5 100644
--- a/mailnews/base/src/nsMsgCopyService.h
+++ b/mailnews/base/src/nsMsgCopyService.h
@@ -29,7 +29,7 @@ class nsCopySource
 {
 public:
     nsCopySource();
-    nsCopySource(nsIMsgFolder* srcFolder);
+    explicit nsCopySource(nsIMsgFolder* srcFolder);
     ~nsCopySource();
     void AddMessage(nsIMsgDBHdr* aMsg);
 
diff --git a/mailnews/base/src/nsMsgDBView.h b/mailnews/base/src/nsMsgDBView.h
index 6dcbbea3b..feba5f14f 100644
--- a/mailnews/base/src/nsMsgDBView.h
+++ b/mailnews/base/src/nsMsgDBView.h
@@ -500,7 +500,7 @@ private:
     NS_DECL_NSISIMPLEENUMERATOR
 
     // nsMsgThreadEnumerator methods:
-    nsMsgViewHdrEnumerator(nsMsgDBView *view);
+    explicit nsMsgViewHdrEnumerator(nsMsgDBView *view);
 
     RefPtr<nsMsgDBView> m_view;
     nsMsgViewIndex m_curHdrIndex;
diff --git a/mailnews/base/src/nsMsgGroupThread.h b/mailnews/base/src/nsMsgGroupThread.h
index 3d1cb4fb4..076d7432a 100644
--- a/mailnews/base/src/nsMsgGroupThread.h
+++ b/mailnews/base/src/nsMsgGroupThread.h
@@ -21,7 +21,7 @@ public:
   friend class nsMsgGroupView;
 
   nsMsgGroupThread();
-  nsMsgGroupThread(nsIMsgDatabase *db);
+  explicit nsMsgGroupThread(nsIMsgDatabase *db);
 
   NS_DECL_NSIMSGTHREAD
   NS_DECL_ISUPPORTS
diff --git a/mailnews/base/src/nsMsgPrintEngine.cpp b/mailnews/base/src/nsMsgPrintEngine.cpp
index d2f8157ed..2a509f380 100644
--- a/mailnews/base/src/nsMsgPrintEngine.cpp
+++ b/mailnews/base/src/nsMsgPrintEngine.cpp
@@ -653,7 +653,7 @@ nsMsgPrintEngine::PrintMsgWindow()
 class nsPrintMsgWindowEvent : public mozilla::Runnable
 {
 public:
-  nsPrintMsgWindowEvent(nsMsgPrintEngine *mpe)
+  explicit nsPrintMsgWindowEvent(nsMsgPrintEngine *mpe)
     : mMsgPrintEngine(mpe)
   {}
 
@@ -672,7 +672,7 @@ private:
 class nsStartNextPrintOpEvent : public mozilla::Runnable
 {
 public:
-  nsStartNextPrintOpEvent(nsMsgPrintEngine *mpe)
+  explicit nsStartNextPrintOpEvent(nsMsgPrintEngine *mpe)
     : mMsgPrintEngine(mpe)
   {}
 
diff --git a/mailnews/base/util/nsMsgKeySet.h b/mailnews/base/util/nsMsgKeySet.h
index c33306ad8..f38dbd013 100644
--- a/mailnews/base/util/nsMsgKeySet.h
+++ b/mailnews/base/util/nsMsgKeySet.h
@@ -80,7 +80,7 @@ public:
 
 protected:
   nsMsgKeySet(/* MSG_NewsHost* host */);
-  nsMsgKeySet(const char* /* , MSG_NewsHost* host */);
+  explicit nsMsgKeySet(const char* /* , MSG_NewsHost* host */);
   bool Grow();
   bool Optimize();
   
diff --git a/mailnews/base/util/nsMsgLineBuffer.h b/mailnews/base/util/nsMsgLineBuffer.h
index 0383b2d43..eff3f7c7e 100644
--- a/mailnews/base/util/nsMsgLineBuffer.h
+++ b/mailnews/base/util/nsMsgLineBuffer.h
@@ -50,7 +50,7 @@ public:
   // flush last line, though it won't be CRLF terminated.
   virtual nsresult FlushLastLine();
 protected:
-  nsMsgLineBuffer(bool convertNewlinesP);
+  explicit nsMsgLineBuffer(bool convertNewlinesP);
   
   nsresult ConvertAndSendBuffer();
   void SetLookingForCRLF(bool b);
diff --git a/mailnews/compose/src/nsMsgSendLater.h b/mailnews/compose/src/nsMsgSendLater.h
index 734396acc..7b6cdf8f7 100644
--- a/mailnews/compose/src/nsMsgSendLater.h
+++ b/mailnews/compose/src/nsMsgSendLater.h
@@ -27,7 +27,7 @@ class SendOperationListener : public nsIMsgSendListener,
                               public nsIMsgCopyServiceListener
 {
 public:
-  SendOperationListener(nsMsgSendLater *aSendLater);
+  explicit SendOperationListener(nsMsgSendLater *aSendLater);
 
   NS_DECL_ISUPPORTS
   NS_DECL_NSIMSGSENDLISTENER
diff --git a/mailnews/compose/src/nsMsgSendPart.h b/mailnews/compose/src/nsMsgSendPart.h
index edb5422ea..84d12bbd7 100644
--- a/mailnews/compose/src/nsMsgSendPart.h
+++ b/mailnews/compose/src/nsMsgSendPart.h
@@ -22,7 +22,7 @@ typedef int (*MSG_SendPartWriteFunc)(const char* line, int32_t size,
 class nsMsgSendPart {
   typedef mozilla::mailnews::MimeEncoder MimeEncoder;
 public:
-    nsMsgSendPart(nsIMsgSend* state, const char *part_charset = NULL);
+    explicit nsMsgSendPart(nsIMsgSend* state, const char *part_charset = NULL);
     virtual ~nsMsgSendPart();	  // Note that the destructor also destroys
 								                // any children that were added.
 
diff --git a/mailnews/compose/src/nsSmtpProtocol.cpp b/mailnews/compose/src/nsSmtpProtocol.cpp
index 54d1e6f64..04347c1d0 100644
--- a/mailnews/compose/src/nsSmtpProtocol.cpp
+++ b/mailnews/compose/src/nsSmtpProtocol.cpp
@@ -2261,10 +2261,12 @@ nsSmtpProtocol::GetUsernamePassword(nsACString &aUsername,
     nsCString hostname;
     rv = smtpServer->GetHostname(hostname);
     NS_ENSURE_SUCCESS(rv, rv);
+    nsAutoString hostnameUTF16;
+    CopyASCIItoUTF16(hostname, hostnameUTF16);
 
     const char16_t *formatStrings[] =
     {
-      NS_ConvertASCIItoUTF16(hostname).get(),
+      hostnameUTF16.get(),
       nullptr
     };
 
diff --git a/mailnews/compose/src/nsSmtpProtocol.h b/mailnews/compose/src/nsSmtpProtocol.h
index c5dba76e3..c8cbf1406 100644
--- a/mailnews/compose/src/nsSmtpProtocol.h
+++ b/mailnews/compose/src/nsSmtpProtocol.h
@@ -109,7 +109,7 @@ public:
 #endif
 
     // Creating a protocol instance requires the URL which needs to be run.
-    nsSmtpProtocol(nsIURI * aURL);
+    explicit nsSmtpProtocol(nsIURI * aURL);
 
     virtual nsresult LoadUrl(nsIURI * aURL, nsISupports * aConsumer = nullptr) override;
     virtual nsresult SendData(const char * dataBuffer, bool aSuppressLogging = false) override;
diff --git a/mailnews/compose/src/nsURLFetcher.h b/mailnews/compose/src/nsURLFetcher.h
index d252b014b..b23a66385 100644
--- a/mailnews/compose/src/nsURLFetcher.h
+++ b/mailnews/compose/src/nsURLFetcher.h
@@ -85,7 +85,7 @@ private:
 class nsURLFetcherStreamConsumer : public nsIStreamListener
 {
 public:
-  nsURLFetcherStreamConsumer(nsURLFetcher* urlFetcher);
+  explicit nsURLFetcherStreamConsumer(nsURLFetcher* urlFetcher);
 
   /* additional members */
   NS_DECL_ISUPPORTS
diff --git a/mailnews/db/msgdb/public/nsDBFolderInfo.h b/mailnews/db/msgdb/public/nsDBFolderInfo.h
index 9b3a51348..b9747feb9 100644
--- a/mailnews/db/msgdb/public/nsDBFolderInfo.h
+++ b/mailnews/db/msgdb/public/nsDBFolderInfo.h
@@ -31,7 +31,7 @@ class nsDBFolderInfo : public nsIDBFolderInfo
 public:
   friend class nsMsgDatabase;
   
-  nsDBFolderInfo(nsMsgDatabase *mdb);
+  explicit nsDBFolderInfo(nsMsgDatabase *mdb);
   
   NS_DECL_ISUPPORTS
     // interface methods.
diff --git a/mailnews/db/msgdb/src/nsMailDatabase.cpp b/mailnews/db/msgdb/src/nsMailDatabase.cpp
index 13a53485f..b9202a4b2 100644
--- a/mailnews/db/msgdb/src/nsMailDatabase.cpp
+++ b/mailnews/db/msgdb/src/nsMailDatabase.cpp
@@ -336,7 +336,7 @@ public:
   // nsISimpleEnumerator methods:
   NS_DECL_NSISIMPLEENUMERATOR
 
-  nsMsgOfflineOpEnumerator(nsMailDatabase* db);
+  explicit nsMsgOfflineOpEnumerator(nsMailDatabase* db);
 
 protected:
   virtual ~nsMsgOfflineOpEnumerator();
diff --git a/mailnews/db/msgdb/src/nsMsgDatabase.cpp b/mailnews/db/msgdb/src/nsMsgDatabase.cpp
index 8b366ab5c..eb5f345f6 100644
--- a/mailnews/db/msgdb/src/nsMsgDatabase.cpp
+++ b/mailnews/db/msgdb/src/nsMsgDatabase.cpp
@@ -1024,7 +1024,7 @@ class MsgDBReporter final : public nsIMemoryReporter
 {
   nsMsgDatabase *mDatabase;
 public:
-  MsgDBReporter(nsMsgDatabase *db) : mDatabase(db) {}
+  explicit MsgDBReporter(nsMsgDatabase *db) : mDatabase(db) {}
 
   NS_DECL_ISUPPORTS
   NS_IMETHOD GetName(nsACString &aName)
diff --git a/mailnews/db/msgdb/src/nsMsgHdr.cpp b/mailnews/db/msgdb/src/nsMsgHdr.cpp
index ba1663e3b..136079473 100644
--- a/mailnews/db/msgdb/src/nsMsgHdr.cpp
+++ b/mailnews/db/msgdb/src/nsMsgHdr.cpp
@@ -998,7 +998,7 @@ public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIUTF8STRINGENUMERATOR
 
-  nsMsgPropertyEnumerator(nsMsgHdr* aHdr);
+  explicit nsMsgPropertyEnumerator(nsMsgHdr* aHdr);
   void PrefetchNext();
 
 protected:
diff --git a/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.cpp b/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.cpp
index 0fa5aa1e2..d0336db1d 100644
--- a/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.cpp
+++ b/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.cpp
@@ -898,7 +898,7 @@ public:
     NS_DECL_NSISTREAMLISTENER
     NS_DECL_NSIMSGHEADERSINK
 
-    TokenStreamListener(TokenAnalyzer* analyzer);
+    explicit TokenStreamListener(TokenAnalyzer* analyzer);
 protected:
     virtual ~TokenStreamListener();
     TokenAnalyzer* mAnalyzer;
diff --git a/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.h b/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.h
index 32a9d26d0..a1e2beaab 100644
--- a/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.h
+++ b/mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.h
@@ -40,7 +40,7 @@ struct CorpusToken;
  */
 class TokenEnumeration {
 public:
-    TokenEnumeration(PLDHashTable* table);
+    explicit TokenEnumeration(PLDHashTable* table);
     bool hasMoreTokens();
     BaseToken* nextToken();
 
@@ -96,7 +96,7 @@ public:
     BaseToken* add(const char* word);
 
 protected:
-    TokenHash(uint32_t entrySize);
+    explicit TokenHash(uint32_t entrySize);
     PLArenaPool mWordPool;
     uint32_t mEntrySize;
     PLDHashTable mTokenTable;
diff --git a/mailnews/imap/src/nsAutoSyncState.h b/mailnews/imap/src/nsAutoSyncState.h
index c28c10d60..0b10c8c94 100644
--- a/mailnews/imap/src/nsAutoSyncState.h
+++ b/mailnews/imap/src/nsAutoSyncState.h
@@ -56,7 +56,7 @@ public:
   NS_DECL_NSIAUTOSYNCSTATE
   NS_DECL_NSIURLLISTENER
 
-  nsAutoSyncState(nsImapMailFolder *aOwnerFolder, PRTime aLastSyncTime = 0UL);
+  explicit nsAutoSyncState(nsImapMailFolder *aOwnerFolder, PRTime aLastSyncTime = 0UL);
 
   /// Called by owner folder when new headers are fetched from the server
   void OnNewHeaderFetchCompleted(const nsTArray<nsMsgKey> &aMsgKeyList);
diff --git a/mailnews/imap/src/nsImapFlagAndUidState.h b/mailnews/imap/src/nsImapFlagAndUidState.h
index 6bf5f3fbe..259bc016f 100644
--- a/mailnews/imap/src/nsImapFlagAndUidState.h
+++ b/mailnews/imap/src/nsImapFlagAndUidState.h
@@ -20,7 +20,7 @@ class nsImapFlagAndUidState : public nsIImapFlagAndUidState
 {
 public:
     NS_DECL_THREADSAFE_ISUPPORTS
-    nsImapFlagAndUidState(int numberOfMessages);
+    explicit nsImapFlagAndUidState(int numberOfMessages);
 
     NS_DECL_NSIIMAPFLAGANDUIDSTATE
 
diff --git a/mailnews/imap/src/nsImapMailFolder.cpp b/mailnews/imap/src/nsImapMailFolder.cpp
index 12e687360..4ed12a026 100644
--- a/mailnews/imap/src/nsImapMailFolder.cpp
+++ b/mailnews/imap/src/nsImapMailFolder.cpp
@@ -6363,7 +6363,7 @@ NS_IMETHODIMP nsImapMailFolder::GetOtherUsersWithAccess(
 class AdoptUTF8StringEnumerator final : public nsIUTF8StringEnumerator
 {
 public:
-  AdoptUTF8StringEnumerator(nsTArray<nsCString>* array) :
+  explicit AdoptUTF8StringEnumerator(nsTArray<nsCString>* array) :
     mStrings(array), mIndex(0)
   {}
 
diff --git a/mailnews/imap/src/nsImapMailFolder.h b/mailnews/imap/src/nsImapMailFolder.h
index b2a9430b3..71665ee79 100644
--- a/mailnews/imap/src/nsImapMailFolder.h
+++ b/mailnews/imap/src/nsImapMailFolder.h
@@ -115,7 +115,7 @@ class nsImapMailFolder;
 class nsMsgIMAPFolderACL
 {
 public:
-  nsMsgIMAPFolderACL(nsImapMailFolder *folder);
+  explicit nsMsgIMAPFolderACL(nsImapMailFolder *folder);
   ~nsMsgIMAPFolderACL();
 
   bool SetFolderRightsForUser(const nsACString& userName, const nsACString& rights);
diff --git a/mailnews/imap/src/nsImapProtocol.cpp b/mailnews/imap/src/nsImapProtocol.cpp
index 1d0c98d48..bf00e0206 100644
--- a/mailnews/imap/src/nsImapProtocol.cpp
+++ b/mailnews/imap/src/nsImapProtocol.cpp
@@ -1057,7 +1057,7 @@ void nsImapProtocol::ReleaseUrlState(bool rerunning)
 
 class nsImapThreadShutdownEvent : public mozilla::Runnable {
 public:
-  nsImapThreadShutdownEvent(nsIThread *thread) : mThread(thread) {
+  explicit nsImapThreadShutdownEvent(nsIThread *thread) : mThread(thread) {
   }
   NS_IMETHOD Run() {
     mThread->Shutdown();
@@ -9580,7 +9580,7 @@ nsresult nsImapMockChannel::ReadFromMemCache(nsICacheEntry *entry)
 class nsReadFromImapConnectionFailure : public mozilla::Runnable
 {
 public:
-  nsReadFromImapConnectionFailure(nsImapMockChannel *aChannel)
+  explicit nsReadFromImapConnectionFailure(nsImapMockChannel *aChannel)
     : mImapMockChannel(aChannel)
   {}
 
diff --git a/mailnews/imap/src/nsImapSearchResults.h b/mailnews/imap/src/nsImapSearchResults.h
index b4333417b..b03268d4d 100644
--- a/mailnews/imap/src/nsImapSearchResults.h
+++ b/mailnews/imap/src/nsImapSearchResults.h
@@ -25,7 +25,7 @@ private:
 
 class nsImapSearchResultIterator {
 public:
-    nsImapSearchResultIterator(nsImapSearchResultSequence &sequence);
+    explicit nsImapSearchResultIterator(nsImapSearchResultSequence &sequence);
     virtual ~nsImapSearchResultIterator();
     
     void  ResetIterator();
diff --git a/mailnews/imap/src/nsImapServerResponseParser.h b/mailnews/imap/src/nsImapServerResponseParser.h
index 5b46f8a43..fb5762b6b 100644
--- a/mailnews/imap/src/nsImapServerResponseParser.h
+++ b/mailnews/imap/src/nsImapServerResponseParser.h
@@ -28,7 +28,7 @@ class nsCString;
 class nsImapServerResponseParser : public nsIMAPGenericParser
 {
 public:
-  nsImapServerResponseParser(nsImapProtocol &imapConnection);
+  explicit nsImapServerResponseParser(nsImapProtocol &imapConnection);
   virtual ~nsImapServerResponseParser();
 
   // Overridden from the base parser class
diff --git a/mailnews/imap/src/nsSyncRunnableHelpers.h b/mailnews/imap/src/nsSyncRunnableHelpers.h
index 4740fab10..273810a70 100644
--- a/mailnews/imap/src/nsSyncRunnableHelpers.h
+++ b/mailnews/imap/src/nsSyncRunnableHelpers.h
@@ -27,7 +27,7 @@
 class StreamListenerProxy final : public nsIStreamListener
 {
 public:
-  StreamListenerProxy(nsIStreamListener* receiver)
+  explicit StreamListenerProxy(nsIStreamListener* receiver)
     : mReceiver(receiver)
   { }
 
@@ -45,7 +45,7 @@ private:
 class ImapMailFolderSinkProxy final : public nsIImapMailFolderSink
 {
 public:
-  ImapMailFolderSinkProxy(nsIImapMailFolderSink* receiver)
+  explicit ImapMailFolderSinkProxy(nsIImapMailFolderSink* receiver)
     : mReceiver(receiver)
   {
     NS_ASSERTION(receiver, "Don't allow receiver is nullptr");
@@ -64,7 +64,7 @@ private:
 class ImapServerSinkProxy final : public nsIImapServerSink
 {
 public:
-  ImapServerSinkProxy(nsIImapServerSink* receiver)
+  explicit ImapServerSinkProxy(nsIImapServerSink* receiver)
     : mReceiver(receiver)
   { }
 
@@ -82,7 +82,7 @@ private:
 class ImapMessageSinkProxy final : public nsIImapMessageSink
 {
 public:
-  ImapMessageSinkProxy(nsIImapMessageSink* receiver)
+  explicit ImapMessageSinkProxy(nsIImapMessageSink* receiver)
     : mReceiver(receiver)
   { }
 
@@ -99,7 +99,7 @@ private:
 class ImapProtocolSinkProxy final : public nsIImapProtocolSink
 {
 public:
-  ImapProtocolSinkProxy(nsIImapProtocolSink* receiver)
+  explicit ImapProtocolSinkProxy(nsIImapProtocolSink* receiver)
     : mReceiver(receiver)
   { }
 
diff --git a/mailnews/import/src/nsImportFieldMap.h b/mailnews/import/src/nsImportFieldMap.h
index a25069b1e..314abd800 100644
--- a/mailnews/import/src/nsImportFieldMap.h
+++ b/mailnews/import/src/nsImportFieldMap.h
@@ -24,7 +24,7 @@ public:
 
   NS_DECL_NSIIMPORTFIELDMAP
 
-  nsImportFieldMap(nsIStringBundle *aBundle);
+  explicit nsImportFieldMap(nsIStringBundle *aBundle);
 
    static NS_METHOD Create(nsIStringBundle *aBundle, nsISupports *aOuter, REFNSIID aIID, void **aResult);
 
diff --git a/mailnews/import/src/nsImportMail.cpp b/mailnews/import/src/nsImportMail.cpp
index ad584b8a6..9e0f6bcd2 100644
--- a/mailnews/import/src/nsImportMail.cpp
+++ b/mailnews/import/src/nsImportMail.cpp
@@ -993,7 +993,7 @@ bool nsImportGenericMail::CreateFolder(nsIMsgFolder **ppFolder)
 class GetSubFoldersRunnable : public mozilla::Runnable
 {
 public:
-  GetSubFoldersRunnable(nsIMsgFolder *aFolder);
+  explicit GetSubFoldersRunnable(nsIMsgFolder *aFolder);
   NS_DECL_NSIRUNNABLE
 private:
   nsCOMPtr<nsIMsgFolder> m_folder;
@@ -1182,7 +1182,7 @@ nsresult ProxyCreateSubfolder(nsIMsgFolder *aFolder, const nsAString &aName)
 class ForceDBClosedRunnable : public mozilla::Runnable
 {
 public:
-  ForceDBClosedRunnable(nsIMsgFolder *aFolder);
+  explicit ForceDBClosedRunnable(nsIMsgFolder *aFolder);
   NS_DECL_NSIRUNNABLE
 protected:
   nsCOMPtr<nsIMsgFolder> m_folder;
diff --git a/mailnews/import/text/src/nsTextImport.cpp b/mailnews/import/text/src/nsTextImport.cpp
index 61615e4d7..0b99e652b 100644
--- a/mailnews/import/text/src/nsTextImport.cpp
+++ b/mailnews/import/text/src/nsTextImport.cpp
@@ -51,7 +51,7 @@ PRLogModuleInfo* TEXTIMPORTLOGMODULE;
 class ImportAddressImpl final : public nsIImportAddressBooks
 {
 public:
-  ImportAddressImpl(nsIStringBundle* aStringBundle);
+  explicit ImportAddressImpl(nsIStringBundle* aStringBundle);
 
   static nsresult Create(nsIImportAddressBooks** aImport,
                          nsIStringBundle *aStringBundle);
diff --git a/mailnews/import/vcard/src/nsVCardImport.cpp b/mailnews/import/vcard/src/nsVCardImport.cpp
index 6081c36d7..fc674e496 100644
--- a/mailnews/import/vcard/src/nsVCardImport.cpp
+++ b/mailnews/import/vcard/src/nsVCardImport.cpp
@@ -30,7 +30,7 @@ static NS_DEFINE_IID(kISupportsIID, NS_ISUPPORTS_IID);
 class ImportVCardAddressImpl : public nsIImportAddressBooks
 {
 public:
-  ImportVCardAddressImpl(nsIStringBundle* aStringBundle); 
+  explicit ImportVCardAddressImpl(nsIStringBundle* aStringBundle);
 
   static nsresult Create(
       nsIImportAddressBooks** aImport, nsIStringBundle* aStringBundle);
diff --git a/mailnews/jsaccount/src/DelegateList.h b/mailnews/jsaccount/src/DelegateList.h
index 943b3e726..aa7fc74c8 100644
--- a/mailnews/jsaccount/src/DelegateList.h
+++ b/mailnews/jsaccount/src/DelegateList.h
@@ -20,7 +20,7 @@ class DelegateList : public msgIDelegateList
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_MSGIDELEGATELIST
-  DelegateList(const char *aWindowsPrefix) :
+  explicit DelegateList(const char *aWindowsPrefix) :
     mPrefix(aWindowsPrefix)
   { }
   nsDataHashtable<nsCStringHashKey, bool> mMethods;
diff --git a/mailnews/jsaccount/src/JaAbDirectory.h b/mailnews/jsaccount/src/JaAbDirectory.h
index 4ada7c761..8c7e37ff7 100644
--- a/mailnews/jsaccount/src/JaAbDirectory.h
+++ b/mailnews/jsaccount/src/JaAbDirectory.h
@@ -56,7 +56,7 @@ private:
                 public nsIInterfaceRequestor
   {
     public:
-      Super(JaCppAbDirectoryDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppAbDirectoryDelegator* aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       NS_FORWARD_NSIABDIRECTORY(mFakeThis->JaBaseCppAbDirectory::)
       NS_FORWARD_NSIABCOLLECTION(mFakeThis->JaBaseCppAbDirectory::)
diff --git a/mailnews/jsaccount/src/JaCompose.h b/mailnews/jsaccount/src/JaCompose.h
index b81adda5c..800d1975e 100644
--- a/mailnews/jsaccount/src/JaCompose.h
+++ b/mailnews/jsaccount/src/JaCompose.h
@@ -60,7 +60,7 @@ private:
                 public nsIInterfaceRequestor
   {
     public:
-      Super(JaCppComposeDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppComposeDelegator* aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       // Forward all overridable methods, bypassing JS override.
       NS_FORWARD_NSIMSGCOMPOSE(mFakeThis->JaBaseCppCompose::)
diff --git a/mailnews/jsaccount/src/JaIncomingServer.h b/mailnews/jsaccount/src/JaIncomingServer.h
index 5b0362324..cac0dfce4 100644
--- a/mailnews/jsaccount/src/JaIncomingServer.h
+++ b/mailnews/jsaccount/src/JaIncomingServer.h
@@ -63,7 +63,7 @@ private:
                 public nsIInterfaceRequestor
   {
     public:
-      Super(JaCppIncomingServerDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppIncomingServerDelegator* aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       // Forward all overridable methods, bypassing JS override.
       NS_FORWARD_NSIMSGINCOMINGSERVER(mFakeThis->JaBaseCppIncomingServer::)
diff --git a/mailnews/jsaccount/src/JaMsgFolder.h b/mailnews/jsaccount/src/JaMsgFolder.h
index 514d6e07f..d1b7d37aa 100644
--- a/mailnews/jsaccount/src/JaMsgFolder.h
+++ b/mailnews/jsaccount/src/JaMsgFolder.h
@@ -89,7 +89,7 @@ private:
       // Why fake this? Because this method is fully owned by
       // JaCppMsgFolderDelegator, and this reference is to the "this" of the
       // main method. But it is not really the local "this".
-      Super(JaCppMsgFolderDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppMsgFolderDelegator* aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       NS_FORWARD_NSIMSGFOLDER(mFakeThis->JaBaseCppMsgFolder::)
       NS_FORWARD_NSIRDFRESOURCE(mFakeThis->JaBaseCppMsgFolder::)
diff --git a/mailnews/jsaccount/src/JaSend.h b/mailnews/jsaccount/src/JaSend.h
index c4d8ac3b8..42984798c 100644
--- a/mailnews/jsaccount/src/JaSend.h
+++ b/mailnews/jsaccount/src/JaSend.h
@@ -63,7 +63,7 @@ private:
                 public nsIInterfaceRequestor
   {
     public:
-      Super(JaCppSendDelegator* aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppSendDelegator* aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       // Forward all overridable methods, bypassing JS override.
       NS_FORWARD_NSIMSGSEND(mFakeThis->JaBaseCppSend::)
diff --git a/mailnews/jsaccount/src/JaUrl.h b/mailnews/jsaccount/src/JaUrl.h
index 2de90ae68..c66f88f68 100644
--- a/mailnews/jsaccount/src/JaUrl.h
+++ b/mailnews/jsaccount/src/JaUrl.h
@@ -79,7 +79,7 @@ public:
                 public nsIInterfaceRequestor
   {
     public:
-      Super(JaCppUrlDelegator *aFakeThis) {mFakeThis = aFakeThis;}
+      explicit Super(JaCppUrlDelegator *aFakeThis) {mFakeThis = aFakeThis;}
       NS_DECL_ISUPPORTS
       NS_FORWARD_NSIMSGMAILNEWSURL(mFakeThis->JaBaseCppUrl::)
       NS_FORWARD_NSIURI(mFakeThis->JaBaseCppUrl::)
diff --git a/mailnews/local/src/nsMailboxProtocol.h b/mailnews/local/src/nsMailboxProtocol.h
index 53c65b40f..e030c8d7c 100644
--- a/mailnews/local/src/nsMailboxProtocol.h
+++ b/mailnews/local/src/nsMailboxProtocol.h
@@ -50,7 +50,7 @@ class nsMailboxProtocol : public nsMsgProtocol
 public:
   // Creating a protocol instance requires the URL which needs to be run AND it requires
   // a transport layer.
-  nsMailboxProtocol(nsIURI * aURL);
+  explicit nsMailboxProtocol(nsIURI * aURL);
   virtual ~nsMailboxProtocol();
 
   // initialization function given a new url and transport layer
diff --git a/mailnews/local/src/nsParseMailbox.h b/mailnews/local/src/nsParseMailbox.h
index aac40611a..646cfd533 100644
--- a/mailnews/local/src/nsParseMailbox.h
+++ b/mailnews/local/src/nsParseMailbox.h
@@ -133,7 +133,7 @@ protected:
 class nsMsgMailboxParser : public nsIStreamListener, public nsParseMailMessageState, public nsMsgLineBuffer
 {
 public:
-  nsMsgMailboxParser(nsIMsgFolder *);
+  explicit nsMsgMailboxParser(nsIMsgFolder *);
   nsMsgMailboxParser();
   nsresult Init();
 
diff --git a/mailnews/local/src/nsPop3Protocol.h b/mailnews/local/src/nsPop3Protocol.h
index a937427d1..a332eae84 100644
--- a/mailnews/local/src/nsPop3Protocol.h
+++ b/mailnews/local/src/nsPop3Protocol.h
@@ -254,7 +254,7 @@ class nsPop3Protocol : public nsMsgProtocol,
                        public nsIMsgAsyncPromptListener
 {
 public:
-  nsPop3Protocol(nsIURI* aURL);
+  explicit nsPop3Protocol(nsIURI* aURL);
 
   NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_NSIPOP3PROTOCOL
diff --git a/mailnews/mime/public/MimeHeaderParser.h b/mailnews/mime/public/MimeHeaderParser.h
index 429e759b1..fe9bf59d3 100644
--- a/mailnews/mime/public/MimeHeaderParser.h
+++ b/mailnews/mime/public/MimeHeaderParser.h
@@ -47,7 +47,7 @@ template <uint32_t N = 5>
 class UTF16ArrayAdapter
 {
 public:
-  UTF16ArrayAdapter(nsTArray<nsCString> &aUTF8Array)
+  explicit UTF16ArrayAdapter(nsTArray<nsCString> &aUTF8Array)
   : mUTF8Array(aUTF8Array) {}
   ~UTF16ArrayAdapter() { detail::DoConversion(mUTF16Array, mUTF8Array); }
   operator nsTArray<nsString>&() { return mUTF16Array; }
diff --git a/mailnews/mime/src/nsCMS.h b/mailnews/mime/src/nsCMS.h
index e8f2fdd4b..7c862eb46 100644
--- a/mailnews/mime/src/nsCMS.h
+++ b/mailnews/mime/src/nsCMS.h
@@ -32,7 +32,7 @@ public:
   NS_DECL_NSICMSMESSAGE2
 
   nsCMSMessage();
-  nsCMSMessage(NSSCMSMessage* aCMSMsg);
+  explicit nsCMSMessage(NSSCMSMessage* aCMSMsg);
   nsresult Init();
 
   void referenceContext(nsIInterfaceRequestor* aContext) {m_ctx = aContext;}
diff --git a/mailnews/mime/src/nsSimpleMimeConverterStub.cpp b/mailnews/mime/src/nsSimpleMimeConverterStub.cpp
index 50dcf27fd..ca608b54c 100644
--- a/mailnews/mime/src/nsSimpleMimeConverterStub.cpp
+++ b/mailnews/mime/src/nsSimpleMimeConverterStub.cpp
@@ -164,7 +164,7 @@ MimeSimpleStubClassInitialize(MimeSimpleStubClass *clazz)
 class nsSimpleMimeConverterStub : public nsIMimeContentTypeHandler
 {
 public:
-    nsSimpleMimeConverterStub(const char *aContentType) : mContentType(aContentType) { }
+    explicit nsSimpleMimeConverterStub(const char *aContentType) : mContentType(aContentType) { }
 
     NS_DECL_ISUPPORTS