Remove extern declarations from .cpp files...

... Require the declarations to be in .h files, to be sure graph.pl detects the
dependencies.

Only one more #include was needed in Nyquist.cpp.   This doesn't reveal any
more hidden cycles.

src/AboutDialog.cpp

@@ -80,8 +80,6 @@ static const auto ProgramName =
    //XO("Audacity");
    Verbatim("Audacity");
 
-extern wxString FormatHtmlText( const wxString & Text );
-
 void AboutDialog::CreateCreditsList()
 {
    const auto sysAdminFormat =

src/FFmpeg.h

@@ -1040,6 +1040,8 @@ struct streamContext
 using Scs = ArrayOf<std::unique_ptr<streamContext>>;
 using ScsPtr = std::shared_ptr<Scs>;
 
+extern FFmpegLibs *FFmpegLibsInst();
+
 #endif // USE_FFMPEG
 #endif // __AUDACITY_FFMPEG__
 

src/HelpText.h

@@ -20,5 +20,6 @@ TranslatableString TitleText( const wxString & Key );
 extern const wxString VerCheckArgs();
 extern const wxString VerCheckUrl();
 extern const wxString VerCheckHtml();
+extern wxString FormatHtmlText( const wxString & Text );
 
 #endif

src/commands/ScriptCommandRelay.cpp

@@ -89,11 +89,6 @@ void ScriptCommandRelay::StartScriptServer(tpRegScriptServerFunc scriptFn)
    std::thread(server, scriptFn).detach();
 }
 
-// The void * return is actually a Lisp LVAL and will be cast to such as needed.
-extern void * ExecForLisp( char * pIn );
-extern void * nyq_make_opaque_string( int size, unsigned char *src );
-extern void * nyq_reformat_aud_do_response(const wxString & Str);
-
 void * ExecForLisp( char * pIn )
 {
    wxString Str1(pIn);

src/commands/ScriptCommandRelay.h

@@ -31,4 +31,9 @@ public:
    static void StartScriptServer(tpRegScriptServerFunc scriptFn);
 };
 
+// The void * return is actually a Lisp LVAL and will be cast to such as needed.
+extern void * ExecForLisp( char * pIn );
+extern void * nyq_make_opaque_string( int size, unsigned char *src );
+extern void * nyq_reformat_aud_do_response(const wxString & Str);
+
 #endif /* End of include guard: __SCRIPT_COMMAND_RELAY__ */

src/effects/nyquist/Nyquist.cpp

@@ -3384,12 +3384,6 @@ static LVAL ngettextc()
 #endif
 }
 
-/*--------------------Audacity Automation -------------------------*/
-/* These functions may later move to their own source file. */
-extern void * ExecForLisp( char * pIn );
-extern void * nyq_make_opaque_string( int size, unsigned char *src );
-extern void * nyq_reformat_aud_do_response(const wxString & Str);
-
 void * nyq_make_opaque_string( int size, unsigned char *src ){
     LVAL dst;
     unsigned char * dstp;
@@ -3416,6 +3410,8 @@ void * nyq_reformat_aud_do_response(const wxString & Str) {
    return (void *)dst;
 }
 
+#include "../../commands/ScriptCommandRelay.h"
+
 
 /* xlc_aud_do -- interface to C routine aud_do */
 /**/

src/export/ExportFFmpeg.cpp

@@ -55,8 +55,6 @@ function.
 // Define this to automatically resample audio to the nearest supported sample rate
 #define FFMPEG_AUTO_RESAMPLE 1
 
-extern FFmpegLibs *FFmpegLibsInst();
-
 static bool CheckFFmpegPresence(bool quiet = false)
 {
    bool result = true;

src/export/ExportFFmpegDialogs.cpp

@@ -70,8 +70,6 @@
 
 #if defined(USE_FFMPEG)
 
-extern FFmpegLibs *FFmpegLibsInst();
-
 /// This construction defines a enumeration of UI element IDs, and a static
 /// array of their string representations (this way they're always synchronized).
 /// Do not store the enumerated values in external files, as they may change;

src/import/ImportFFmpeg.cpp

@@ -163,8 +163,6 @@ static const auto exts = {
 #include "../ondemand/ODDecodeFFmpegTask.h"
 #endif
 
-extern FFmpegLibs *FFmpegLibsInst();
-
 class FFmpegImportFileHandle;
 
 /// A representative of FFmpeg loader in

src/ondemand/ODDecodeFFmpegTask.cpp

@@ -32,9 +32,6 @@
 #include "../FFmpeg.h"      // which brings in avcodec.h, avformat.h
 
 
-extern FFmpegLibs *FFmpegLibsInst();
-
-
 #define ODFFMPEG_SEEKING_TEST_UNKNOWN 0
 #define ODFFMPEG_SEEKING_TEST_FAILED -1
 #define ODFFMPEG_SEEKING_TEST_SUCCESS 1