Error LNK2019: unresolved external symbol "class juce::AudioProcessor

LaudriLabs · December 11, 2024, 2:46pm

I just started coding C++ to get into VST’s and really know nothing about compiling or coding in C++ for that matter as I normally code in python.

I get this error when running cmake --build . --config Debug
Only thing is I have the createpluginfilter() within my code as follows:

#include “PluginProcessor.h”

juce::AudioProcessor* JUCE_CALLTYPE createPluginFilter()
{
return new FrequencyShiftAudioProcessor();
}

It’s within its own file under pluginentry.cpp. Originally I had it within PluginProcessor.cpp and did not work there either. Any help to this problem would be appreciated cause I can’t figure it out for the life of me.

I’ll link my cmakelist:

cmake_minimum_required(VERSION 3.15)

Project setup

project(BinauralShifter VERSION 1.0.0 DESCRIPTION “A binaural audio processing plugin”)

Enable debug symbols and set build type if not specified

if(NOT CMAKE_BUILD_TYPE)
set(CMAKE_BUILD_TYPE Debug)
endif()

Include JUCE

add_subdirectory(JUCE)

Set C++ standard

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

Plugin configuration

set(PROJECT_NAME “BinauralShifter”)
set(COMPANY_NAME “LaudriLabs”)
set(PLUGIN_NAME “Binaural Shifter”)
set(PLUGIN_DESCRIPTION “Binaural audio processing plugin”)
set(PLUGIN_VERSION “1.0.0”)

Define source files

set(SOURCE_FILES
Source/PluginProcessor.cpp
Source/PluginProcessor.h
Source/PluginEditor.cpp
Source/PluginEditor.h
Source/GranularShifter.h
Source/Parameters.h
Source/AudioLogger.h
Source/PluginEntry.cpp
)

Plugin setup

juce_add_plugin(${PROJECT_NAME}
VERSION ${PLUGIN_VERSION}
COMPANY_NAME ${COMPANY_NAME}
PRODUCT_NAME ${PLUGIN_NAME}
DESCRIPTION ${PLUGIN_DESCRIPTION}
PLUGIN_MANUFACTURER_CODE LLBS
PLUGIN_CODE Bshf
FORMATS VST3 Standalone # Added Standalone format for easier testing
VST3_CATEGORIES “Fx”
IS_SYNTH FALSE
NEEDS_MIDI_INPUT FALSE
NEEDS_MIDI_OUTPUT FALSE
IS_MIDI_EFFECT FALSE
EDITOR_WANTS_KEYBOARD_FOCUS FALSE
COPY_PLUGIN_AFTER_BUILD TRUE # Automatically copy to system VST folder
SOURCES ${SOURCE_FILES}
)

Add required JUCE modules

target_compile_definitions(${PROJECT_NAME}
PUBLIC
JUCE_WEB_BROWSER=0
JUCE_USE_CURL=0
JUCE_VST3_CAN_REPLACE_VST2=0
JUCE_DISPLAY_SPLASH_SCREEN=0
JUCE_REPORT_APP_USAGE=0
$<$CONFIG:Debug:JUCE_DEBUG=1>
)

Set optimization flags for Release builds

if(CMAKE_BUILD_TYPE STREQUAL “Release”)
target_compile_options(${PROJECT_NAME} PRIVATE
$<$<CXX_COMPILER_ID:MSVC>:/O2>
$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-O3>
)
endif()

Generate JUCE header files

juce_generate_juce_header(${PROJECT_NAME})

Install targets

include(GNUInstallDirs)
install(TARGETS ${PROJECT_NAME}
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)

Terminal error:

<obscured_path>/build>cmake --build . --config Debug
MSBuild version 17.9.5+33de0b227 for .NET Framework

  Checking File Globs
  1>Checking Build System
  Generating BinauralShifter_artefacts/JuceLibraryCode/BinauralShifter_resources.rc
  Building Custom Rule <obscured_path>/CMakeLists.txt
  BinauralShifter_rc_lib.vcxproj -> <obscured_path>/build/BinauralShifter_rc_lib.dir/Debug/BinauralShifter_rc_lib.lib
  Generating BinauralShifter_artefacts/JuceLibraryCode/JuceHeader.h
  Building Custom Rule <obscured_path>/CMakeLists.txt
  juce_audio_processors.cpp
  juce_audio_processors_ara.cpp
  juce_audio_processors_lv2_libs.cpp
  juce_gui_extra.cpp
  juce_gui_basics.cpp
  juce_graphics.cpp
  juce_graphics_Harfbuzz.cpp
  juce_events.cpp
  juce_core.cpp
  juce_core_CompilationTime.cpp
  juce_data_structures.cpp
  juce_audio_basics.cpp
  juce_audio_utils.cpp
  juce_audio_formats.cpp
  juce_audio_devices.cpp
  juce_dsp.cpp
<obscured_path>/juce_gui_basics.cpp(61): warning : This version of JUCE does not use the splash screen, the flag JUCE_DISPLAY_SPLASH_SCREEN is ignored [<obscured_path>/build/BinauralShifter.vcxproj]
  juce_graphics_Sheenbidi.c
  BinauralShifter.vcxproj -> <obscured_path>/build/BinauralShifter_artefacts/Debug/Binaural Shifter_SharedCode.lib
  Building Custom Rule <obscured_path>/CMakeLists.txt
  juce_VST3ManifestHelper.cpp
  juce_vst3_helper.vcxproj -> <obscured_path>/build/Debug/juce_vst3_helper.exe
  Building Custom Rule <obscured_path>/CMakeLists.txt
  juce_audio_plugin_client_AAX.cpp
  juce_audio_plugin_client_AAX_utils.cpp
  juce_audio_plugin_client_ARA.cpp
  juce_audio_plugin_client_LV2.cpp
  juce_audio_plugin_client_Standalone.cpp
  juce_audio_plugin_client_Unity.cpp
  juce_audio_plugin_client_VST2.cpp
  juce_audio_plugin_client_VST3.cpp
     Creating library <obscured_path>/build/BinauralShifter_artefacts/Debug/VST3/Binaural Shifter.lib and object <obscured_path>/build/BinauralShifter_artefacts/Debug/VST3/Binaural Shifter.exp
juce_audio_plugin_client_VST3.obj : error LNK2019: unresolved external symbol "class juce::AudioProcessor * __cdecl createPluginFilter(void)" (?createPluginFilter@@YAPEAVAudioProcessor@juce@@XZ) referenced in function "class std::unique_ptr<class juce::AudioProcessor,struct std::default_delete<class juce::AudioProcessor> > __cdecl juce::createPluginFilterOfType(enum juce::AudioProcessor::WrapperType)" (?createPluginFilterOfType@juce@@YA?AV?$unique_ptr@VAudioProcessor@juce@@U?$default_delete@VAudioProcessor@juce@@@std@@@std@@W4WrapperType@AudioProcessor@1@@Z) [<obscured_path>/build/BinauralShifter_VST3.vcxproj]
<obscured_path>/build/BinauralShifter_artefacts/Debug/VST3/Binaural Shifter.vst3 : fatal error LNK1120: 1 unresolved externals [<obscured_path>/build/BinauralShifter_VST3.vcxproj]

<obscured_path>/build>cmake --build . -v  --config Debug
Change Dir: '<obscured_path>/build'

Run Build Command(s): "<compiler_path>/MSBuild.exe" ALL_BUILD.vcxproj /p:Configuration=Debug /p:Platform=x64 /p:VisualStudioVersion=17.0 /v:n
MSBuild version 17.9.5+33de0b227 for .NET Framework
Build started 12/11/2024 7:27:16 AM.

Project "<obscured_path>/build/ALL_BUILD.vcxproj" on node 1 (default targets).
Project "<obscured_path>/build/ALL_BUILD.vcxproj" (1) is building "<obscured_path>/build/ZERO_CHECK.vcxproj" (2) on node 1 (default targets).
PrepareForBuild:
  Structured output is enabled. The formatting of compiler diagnostics will reflect the error hierarchy. See https://aka.ms/cpp/structured-output for more details.
InitializeBuildStatus:
  Creating "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\unsuccessfulbuild" because "AlwaysCreate" was specified.
  Touching "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\unsuccessfulbuild".
PreBuildEvent:
  Checking File Globs
  setlocal
  "<compiler_path>/cmake.exe" -P "<obscured_path>/build/CMakeFiles/VerifyGlobs.cmake"
  if %errorlevel% neq 0 goto :cmEnd
  :cmEnd
  endlocal & call :cmErrorLevel %errorlevel% & goto :cmDone
  :cmErrorLevel
  exit /b %1
  :cmDone
  if %errorlevel% neq 0 goto :VCEnd
  :VCEnd
CustomBuild:
  All outputs are up-to-date.
FinalizeBuildStatus:
  Deleting file "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\unsuccessfulbuild".
  Touching "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\ZERO_CHECK.lastbuildstate".
Done Building Project "<obscured_path>/build/ALL_BUILD.vcxproj" (default targets) -- FAILED.

Build FAILED.

"<obscured_path>/build/ALL_BUILD.vcxproj" (default target) (1) ->
"<obscured_path>/build/BinauralShifter_VST3.vcxproj" (default target) (3) ->
(Link target) ->
  juce_audio_plugin_client_VST3.obj : error LNK2019: unresolved external symbol "class juce::AudioProcessor * __cdecl createPluginFilter(void)" (?createPluginFilter@@YAPEAVAudioProcessor@juce@@XZ) referenced in function "class std::unique_ptr<class juce::AudioProcessor,struct std::default_delete<class juce::AudioProcessor> > __cdecl juce::createPluginFilterOfType(enum juce::AudioProcessor::WrapperType)" (?createPluginFilterOfType@juce@@YA?AV?$unique_ptr@VAudioProcessor@juce@@U?$default_delete@VAudioProcessor@juce@@@std@@@std@@W4WrapperType@AudioProcessor@1@@Z) [<obscured_path>/build/BinauralShifter_VST3.vcxproj]
  <obscured_path>/build/BinauralShifter_artefacts/Debug/VST3/Binaural Shifter.vst3 : fatal error LNK1120: 1 unresolved externals [<obscured_path>/build/BinauralShifter_VST3.vcxproj]

Done Building Project "<obscured_path>/build/BinauralShifter_VST3.vcxproj" (default targets) -- FAILED.

Done Building Project "<obscured_path>/build/ALL_BUILD.vcxproj" (default targets) -- FAILED.

Build FAILED

hugoderwolf · December 12, 2024, 8:14am

It doesn’t seem to compile any of your own source files, only the JUCE ones.

On a closer look, juce_add_plugin doesn’t have a SOURCES argument, which you are using to add your sources. Do this instead:

target_sources( ${PROJECT_NAME} PRIVATE
    Source/PluginProcessor.cpp
    Source/PluginProcessor.h
    Source/PluginEditor.cpp
    Source/PluginEditor.h
    Source/GranularShifter.h
    Source/Parameters.h
    Source/AudioLogger.h
    Source/PluginEntry.cpp
)

Topic		Replies	Views
Error LNK2019/LNK1120 - unresolved external symbol createPluginFilter() when compiling VST3 with JUCE + CMake Development	0	61	April 17, 2025
Why can´t i build my Juce Audio Plugin into .exe, .vst3 files? General JUCE discussion	2	588	February 15, 2022
Cmake linking errors when using clion CMake	2	1055	June 12, 2021
Class juce::AudioProcessor - external symbol unresolved reference Windows	1	1031	April 12, 2021
Error LNK2019: unresolved external symbol "public: void __cdecl juce::dsp::LookupTableTransform Audio Plugins	4	1480	January 5, 2023

Error LNK2019: unresolved external symbol "class juce::AudioProcessor

Project setup

Enable debug symbols and set build type if not specified

Include JUCE

Set C++ standard

Plugin configuration

Define source files

Plugin setup

Add required JUCE modules

Set optimization flags for Release builds

Link JUCE libraries

Generate JUCE header files

Install targets

Purchase

Discover

Learn

Support

About

Events

Error LNK2019: unresolved external symbol "class juce::AudioProcessor

Project setup

Enable debug symbols and set build type if not specified

Include JUCE

Set C++ standard

Plugin configuration

Define source files

Plugin setup

Add required JUCE modules

Set optimization flags for Release builds

Link JUCE libraries

Generate JUCE header files

Install targets

Related topics

Purchase

Discover

Learn

Support

About

Events