build: extract CMake plugin/harness modules and add platform build scripts

Split CMakeLists.txt into cmake/Plugin.cmake (production formats and
MinGW link flags) and cmake/Harness.cmake (console test harness with
CTest registration). Add SERUMALT_BUILD_PLUGIN and SERUMALT_BUILD_TESTS
options so production and harness builds are mutually exclusive and
each omits the other's targets.

Add build_linux.sh, build_macos.sh, and build_harness.sh with host
validation, env-overridable build dirs, and explicit option flags.
Rewrite build_windows.sh to use the checked-in mingw64-toolchain.cmake
instead of regenerating it, validate all required tools, and stage
with cmake -E copy_directory.

Broaden .gitignore to cover all build_*/ directories.

.gitignore

@@ -1,6 +1,6 @@
 # CMake build directories
 /build/
-/build_windows/
+/build_*/
 /cmake-build-*/
 
 # Windows output staging

CMakeLists.txt

@@ -9,43 +9,20 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+option(SERUMALT_BUILD_PLUGIN "Build production plugin and standalone formats" ON)
+option(SERUMALT_BUILD_TESTS "Build the headless QA harness" OFF)
+
+if(NOT SERUMALT_BUILD_PLUGIN AND NOT SERUMALT_BUILD_TESTS)
+    message(FATAL_ERROR "Enable SERUMALT_BUILD_PLUGIN or SERUMALT_BUILD_TESTS")
+endif()
+
 # ---------------------------------------------------------------------------
 # JUCE
 # ---------------------------------------------------------------------------
 if(NOT DEFINED JUCE_ROOT)
     set(JUCE_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/third_party/JUCE")
 endif()
-add_subdirectory("${JUCE_ROOT}")
+add_subdirectory("${JUCE_ROOT}" "${CMAKE_CURRENT_BINARY_DIR}/third_party/JUCE")
-
-# ---------------------------------------------------------------------------
-# Plugin target
-# ---------------------------------------------------------------------------
-# JUCE 7.0.12 builds its VST3 manifest helper (juce_vst3_helper) with the same
-# toolchain as the plugin itself. When cross-compiling, that produces a Windows
-# .exe which cannot run on the Linux build host, so we disable the automatic
-# manifest step and inject a platform-independent moduleinfo.json afterwards
-# (see build_windows.sh). Native builds keep the automatic step.
-set(SERUMALT_VST3_AUTO_MANIFEST TRUE)
-if(CMAKE_CROSSCOMPILING)
-    set(SERUMALT_VST3_AUTO_MANIFEST FALSE)
-endif()
-
-juce_add_plugin(SerumAlt
-    VERSION 1.0.0
-    COMPANY_NAME "SerumAlt Audio"
-    IS_SYNTH TRUE
-    NEEDS_MIDI_INPUT TRUE
-    NEEDS_MIDI_OUTPUT FALSE
-    IS_MIDI_EFFECT FALSE
-    EDITOR_WANTS_KEYBOARD_FOCUS FALSE
-    PLUGIN_MANUFACTURER_CODE Salt
-    PLUGIN_CODE Sera
-    BUNDLE_ID com.serumalt.SerumAlt
-    FORMATS VST3 AU Standalone
-    PRODUCT_NAME "SerumAlt"
-    VST3_AUTO_MANIFEST ${SERUMALT_VST3_AUTO_MANIFEST})
-
-juce_generate_juce_header(SerumAlt)
 
 set(SERUMALT_SOURCES
     Source/PluginProcessor.cpp
@@ -86,46 +63,33 @@ set(SERUMALT_SOURCES
     Source/GUI/Panel.cpp
     Source/Presets/FactoryPresets.cpp)
 
-target_sources(SerumAlt PRIVATE ${SERUMALT_SOURCES})
+function(serumalt_configure_target target)
-
+    juce_generate_juce_header(${target})
-target_compile_definitions(SerumAlt
+    target_sources(${target} PRIVATE ${SERUMALT_SOURCES})
+    target_compile_definitions(${target}
         PUBLIC
             JUCE_WEB_BROWSER=0
             JUCE_USE_CURL=0
             JUCE_VST3_CAN_REPLACE_VST2=0)
-
+    target_link_libraries(${target}
-target_link_libraries(SerumAlt
         PRIVATE
             juce::juce_audio_utils
             juce::juce_dsp
         PUBLIC
             juce::juce_recommended_config_flags
             juce::juce_recommended_warning_flags)
+    if(MSVC)
+        target_compile_options(${target} PRIVATE /W4)
+    else()
+        target_compile_options(${target} PRIVATE -Wall -Wextra)
+    endif()
+endfunction()
 
-# ---------------------------------------------------------------------------
+if(SERUMALT_BUILD_PLUGIN)
-# Headless QA harness (console app that drives the processor and checks output)
+    include(cmake/Plugin.cmake)
-# ---------------------------------------------------------------------------
+endif()
-option(SERUMALT_BUILD_TESTS "Build the headless QA harness" ON)
 
 if(SERUMALT_BUILD_TESTS)
-    juce_add_console_app(SerumAltTest)
+    enable_testing()
-    juce_generate_juce_header(SerumAltTest)
+    include(cmake/Harness.cmake)
-    target_sources(SerumAltTest PRIVATE ${SERUMALT_SOURCES} Source/Tests/TestMain.cpp)
-    target_compile_definitions(SerumAltTest
-        PUBLIC
-            JUCE_WEB_BROWSER=0
-            JUCE_USE_CURL=0)
-    target_link_libraries(SerumAltTest
-        PRIVATE
-            juce::juce_audio_utils
-            juce::juce_dsp
-        PUBLIC
-            juce::juce_recommended_config_flags
-            juce::juce_recommended_warning_flags)
-endif()
-
-if(MSVC)
-    target_compile_options(SerumAlt PRIVATE /W4)
-else()
-    target_compile_options(SerumAlt PRIVATE -Wall -Wextra)
 endif()

build_harness.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+BUILD_DIR="${BUILD_DIR:-$SCRIPT_DIR/build_harness}"
+BUILD_TYPE="${BUILD_TYPE:-Release}"
+export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL:-2}"
+
+if [[ $# -gt 1 || ( $# -eq 1 && "$1" != --run ) ]]; then
+    echo "Usage: $0 [--run]" >&2
+    exit 1
+fi
+
+TOOLS=(cmake ninja "${CC:-cc}" "${CXX:-c++}")
+case "$(uname -s)" in
+    Linux) TOOLS+=(pkg-config) ;;
+    Darwin) TOOLS+=(xcrun) ;;
+    *) echo "ERROR: build_harness.sh requires a native Linux or macOS host." >&2; exit 1 ;;
+esac
+if [[ $# -eq 1 ]]; then
+    TOOLS+=(ctest)
+fi
+for tool in "${TOOLS[@]}"; do
+    if ! command -v "$tool" >/dev/null 2>&1; then
+        echo "ERROR: $tool not found. See README.md prerequisites." >&2
+        exit 1
+    fi
+done
+
+if [[ "$(uname -s)" == Darwin ]]; then
+    xcrun --sdk macosx --show-sdk-path
+fi
+
+echo "Configuring the native QA harness only in $BUILD_DIR ($BUILD_TYPE)..."
+cmake -S "$SCRIPT_DIR" -B "$BUILD_DIR" -G Ninja \
+    -DCMAKE_BUILD_TYPE="$BUILD_TYPE" \
+    -DSERUMALT_BUILD_PLUGIN=OFF \
+    -DSERUMALT_BUILD_TESTS=ON
+
+echo "Building SerumAltTest..."
+cmake --build "$BUILD_DIR" --config "$BUILD_TYPE" --target SerumAltTest
+
+if [[ $# -eq 1 ]]; then
+    echo "Running the QA harness with CTest..."
+    ctest --test-dir "$BUILD_DIR" --build-config "$BUILD_TYPE" --output-on-failure --no-tests=error
+fi
+
+echo "Done. QA harness: $BUILD_DIR/SerumAltTest_artefacts/$BUILD_TYPE/SerumAltTest"

build_linux.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+BUILD_DIR="${BUILD_DIR:-$SCRIPT_DIR/build_linux}"
+BUILD_TYPE="${BUILD_TYPE:-Release}"
+export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL:-2}"
+
+if [[ "$(uname -s)" != Linux ]]; then
+    echo "ERROR: build_linux.sh requires a Linux host." >&2
+    exit 1
+fi
+
+for tool in cmake ninja pkg-config "${CC:-cc}" "${CXX:-c++}"; do
+    if ! command -v "$tool" >/dev/null 2>&1; then
+        echo "ERROR: $tool not found. See README.md prerequisites." >&2
+        exit 1
+    fi
+done
+
+echo "Configuring Linux production targets in $BUILD_DIR ($BUILD_TYPE)..."
+cmake -S "$SCRIPT_DIR" -B "$BUILD_DIR" -G Ninja \
+    -DCMAKE_BUILD_TYPE="$BUILD_TYPE" \
+    -DSERUMALT_BUILD_PLUGIN=ON \
+    -DSERUMALT_BUILD_TESTS=OFF
+
+echo "Building Linux VST3 and standalone..."
+cmake --build "$BUILD_DIR" --config "$BUILD_TYPE" --target SerumAlt_VST3 SerumAlt_Standalone
+
+echo "Done. Linux artifacts: $BUILD_DIR/SerumAlt_artefacts/$BUILD_TYPE"

build_macos.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+BUILD_DIR="${BUILD_DIR:-$SCRIPT_DIR/build_macos}"
+BUILD_TYPE="${BUILD_TYPE:-Release}"
+export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL:-2}"
+
+if [[ "$(uname -s)" != Darwin ]]; then
+    echo "ERROR: build_macos.sh requires macOS and the Apple SDK." >&2
+    exit 1
+fi
+
+for tool in cmake ninja xcrun "${CC:-clang}" "${CXX:-clang++}"; do
+    if ! command -v "$tool" >/dev/null 2>&1; then
+        echo "ERROR: $tool not found. See README.md prerequisites." >&2
+        exit 1
+    fi
+done
+xcrun --sdk macosx --show-sdk-path
+
+OSX_OPTIONS=("-DCMAKE_BUILD_TYPE=$BUILD_TYPE")
+if [[ -n "${CMAKE_OSX_ARCHITECTURES:-}" ]]; then
+    OSX_OPTIONS+=("-DCMAKE_OSX_ARCHITECTURES=$CMAKE_OSX_ARCHITECTURES")
+fi
+if [[ -n "${CMAKE_OSX_DEPLOYMENT_TARGET:-}" ]]; then
+    OSX_OPTIONS+=("-DCMAKE_OSX_DEPLOYMENT_TARGET=$CMAKE_OSX_DEPLOYMENT_TARGET")
+fi
+
+echo "Configuring macOS production targets in $BUILD_DIR ($BUILD_TYPE)..."
+cmake -S "$SCRIPT_DIR" -B "$BUILD_DIR" -G Ninja \
+    "${OSX_OPTIONS[@]}" \
+    -DSERUMALT_BUILD_PLUGIN=ON \
+    -DSERUMALT_BUILD_TESTS=OFF
+
+echo "Building macOS VST3, AU, and standalone..."
+cmake --build "$BUILD_DIR" --config "$BUILD_TYPE" --target SerumAlt_VST3 SerumAlt_AU SerumAlt_Standalone
+
+echo "Done. macOS artifacts: $BUILD_DIR/SerumAlt_artefacts/$BUILD_TYPE"

build_windows.sh

@@ -7,60 +7,60 @@ set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$SCRIPT_DIR"
 
-TOOLCHAIN_FILE="mingw64-toolchain.cmake"
+TOOLCHAIN_FILE="$SCRIPT_DIR/mingw64-toolchain.cmake"
-BUILD_DIR="build_windows"
+BUILD_DIR="${BUILD_DIR:-$SCRIPT_DIR/build_windows}"
-OUTPUT_DIR="SerumAlt_Windows"
+BUILD_TYPE="${BUILD_TYPE:-Release}"
+OUTPUT_DIR="${OUTPUT_DIR:-$SCRIPT_DIR/SerumAlt_Windows}"
 PLUGIN_NAME="SerumAlt"
+export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL:-2}"
 
-# 1. Check for the MinGW-w64 cross-compiler and exit if it is not found.
+if [[ "$(uname -s)" != Linux ]]; then
-if ! command -v x86_64-w64-mingw32-g++ >/dev/null 2>&1; then
+    echo "ERROR: build_windows.sh cross-compiles from Linux using MinGW-w64." >&2
-    echo "ERROR: x86_64-w64-mingw32-g++ not found." >&2
-    echo "Please install the MinGW-w64 cross-compiler first, e.g.:" >&2
-    echo "    sudo pacman -S mingw-w64-gcc" >&2
     exit 1
 fi
 
+# 1. Check for the host tools and MinGW-w64 cross-compiler.
+for tool in cmake ninja pkg-config "${CC:-cc}" "${CXX:-c++}" \
+    x86_64-w64-mingw32-gcc x86_64-w64-mingw32-g++ \
+    x86_64-w64-mingw32-windres x86_64-w64-mingw32-ar \
+    x86_64-w64-mingw32-ranlib x86_64-w64-mingw32-strip; do
+    if ! command -v "$tool" >/dev/null 2>&1; then
+        echo "ERROR: $tool not found. See README.md prerequisites." >&2
+        exit 1
+    fi
+done
+
 echo "Found: $(command -v x86_64-w64-mingw32-g++)"
 
-# 2. Generate the CMake toolchain file.
+# 2. Use the checked-in CMake toolchain file without overwriting it.
-cat > "$TOOLCHAIN_FILE" <<'EOF'
+if [[ ! -f "$TOOLCHAIN_FILE" ]]; then
-set(CMAKE_SYSTEM_NAME Windows)
+    echo "ERROR: Toolchain file not found: $TOOLCHAIN_FILE" >&2
-set(CMAKE_SYSTEM_PROCESSOR x86_64)
+    exit 1
-
+fi
-set(CMAKE_C_COMPILER x86_64-w64-mingw32-gcc)
+echo "Using toolchain file: $TOOLCHAIN_FILE"
-set(CMAKE_CXX_COMPILER x86_64-w64-mingw32-g++)
-set(CMAKE_RC_COMPILER x86_64-w64-mingw32-windres)
-set(CMAKE_AR x86_64-w64-mingw32-ar)
-set(CMAKE_RANLIB x86_64-w64-mingw32-ranlib)
-set(CMAKE_STRIP x86_64-w64-mingw32-strip)
-
-set(CMAKE_FIND_ROOT_PATH /usr/x86_64-w64-mingw32)
-set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
-set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
-set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
-set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
-EOF
-
-echo "Wrote toolchain file: $TOOLCHAIN_FILE"
 
 # 3. Configure with CMake + Ninja (VST3-only cross build, no test harness).
-cmake -S . -B "$BUILD_DIR" -G Ninja \
+echo "Configuring Windows VST3 in $BUILD_DIR ($BUILD_TYPE)..."
-    -DCMAKE_BUILD_TYPE=Release \
+cmake -S "$SCRIPT_DIR" -B "$BUILD_DIR" -G Ninja \
+    -DCMAKE_BUILD_TYPE="$BUILD_TYPE" \
     -DCMAKE_TOOLCHAIN_FILE="$TOOLCHAIN_FILE" \
+    -DSERUMALT_BUILD_PLUGIN=ON \
     -DSERUMALT_BUILD_TESTS=OFF
 
 # 4. Build the VST3 target.
-cmake --build "$BUILD_DIR" --target SerumAlt_VST3
+echo "Building Windows VST3..."
+cmake --build "$BUILD_DIR" --config "$BUILD_TYPE" --target SerumAlt_VST3
 
 # 5. Inject the VST3 moduleinfo.json.
 #    The automatic manifest step is disabled when cross-compiling (see
-#    CMakeLists.txt), because JUCE's manifest helper is a host tool that would
+#    cmake/Plugin.cmake), because JUCE's manifest helper is a host tool that would
 #    otherwise be built as a Windows executable. The moduleinfo content is
-#    deterministic and platform-independent: it depends only on the plugin's
+#    deterministic for this Windows plugin: it depends on the plugin's
-#    name, manufacturer/plugin codes, and version, so we write the identical
+#    name, manufacturer/plugin codes, and version, so we write the same metadata
-#    file that the native helper generates. Keep it in sync with the metadata
+#    that the native Windows helper generates. Keep it in sync with the metadata
-#    in CMakeLists.txt (PLUGIN_CODE, PLUGIN_MANUFACTURER_CODE, VERSION).
+#    in CMakeLists.txt and cmake/Plugin.cmake, including the vendored VST3 SDK version.
-VST3_BUNDLE="$BUILD_DIR/${PLUGIN_NAME}_artefacts/Release/VST3/$PLUGIN_NAME.vst3"
+VST3_BUNDLE="$BUILD_DIR/${PLUGIN_NAME}_artefacts/$BUILD_TYPE/VST3/$PLUGIN_NAME.vst3"
+echo "Writing Windows VST3 manifest..."
 mkdir -p "$VST3_BUNDLE/Contents/Resources"
 cat > "$VST3_BUNDLE/Contents/Resources/moduleinfo.json" <<'EOF'
 {
@@ -73,8 +73,8 @@ cat > "$VST3_BUNDLE/Contents/Resources/moduleinfo.json" <<'EOF'
     "Flags": {
       "Unicode": true,
       "Classes Discardable": false,
-      "Component Non Discardable": false,
+      "Component Non Discardable": false
-    },
+    }
   },
   "Classes": [
     {
@@ -86,12 +86,11 @@ cat > "$VST3_BUNDLE/Contents/Resources/moduleinfo.json" <<'EOF'
       "SDKVersion": "VST 3.7.8",
       "Sub Categories": [
         "Instrument",
-        "Synth",
+        "Synth"
       ],
       "Class Flags": 2,
       "Cardinality": 2147483647,
-      "Snapshots": [
+      "Snapshots": []
-      ],
     },
     {
       "CID": "ABCDEF011234ABCD53616C7453657261",
@@ -102,12 +101,11 @@ cat > "$VST3_BUNDLE/Contents/Resources/moduleinfo.json" <<'EOF'
       "SDKVersion": "VST 3.7.8",
       "Sub Categories": [
         "Instrument",
-        "Synth",
+        "Synth"
       ],
       "Class Flags": 2,
       "Cardinality": 2147483647,
-      "Snapshots": [
+      "Snapshots": []
-      ],
     },
     {
       "CID": "ABCDEF01C0DEF00D53616C7453657261",
@@ -118,17 +116,15 @@ cat > "$VST3_BUNDLE/Contents/Resources/moduleinfo.json" <<'EOF'
       "SDKVersion": "VST 3.7.8",
       "Class Flags": 0,
       "Cardinality": 2147483647,
-      "Snapshots": [
+      "Snapshots": []
-      ],
+    }
-    },
+  ]
-  ],
 }
 EOF
 
-# 6. Copy the resulting .vst3 bundle to SerumAlt_Windows/.
+# 6. Copy the resulting .vst3 bundle to SerumAlt_Windows/ without deleting files.
-mkdir -p "$OUTPUT_DIR"
+echo "Staging Windows VST3 in $OUTPUT_DIR..."
-rm -rf "$OUTPUT_DIR/$PLUGIN_NAME.vst3"
+cmake -E copy_directory "$VST3_BUNDLE" "$OUTPUT_DIR/$PLUGIN_NAME.vst3"
-cp -R "$BUILD_DIR/${PLUGIN_NAME}_artefacts/Release/VST3/$PLUGIN_NAME.vst3" "$OUTPUT_DIR/"
 
 echo
-echo "Done. Windows VST3 plugin at: $SCRIPT_DIR/$OUTPUT_DIR/$PLUGIN_NAME.vst3"
+echo "Done. Windows VST3 plugin at: $OUTPUT_DIR/$PLUGIN_NAME.vst3"

cmake/Harness.cmake

@@ -0,0 +1,7 @@
+# ---------------------------------------------------------------------------
+# Headless QA harness (console app that drives the processor and checks output)
+# ---------------------------------------------------------------------------
+juce_add_console_app(SerumAltTest)
+serumalt_configure_target(SerumAltTest)
+target_sources(SerumAltTest PRIVATE Source/Tests/TestMain.cpp)
+add_test(NAME SerumAltTest COMMAND SerumAltTest)

cmake/Plugin.cmake

@@ -0,0 +1,52 @@
+# ---------------------------------------------------------------------------
+# Plugin target
+# ---------------------------------------------------------------------------
+# JUCE 7.0.12 builds its VST3 manifest helper (juce_vst3_helper) with the same
+# toolchain as the plugin itself. When cross-compiling, that produces a Windows
+# .exe which cannot run on the Linux build host, so we disable the automatic
+# manifest step and inject a Windows moduleinfo.json afterwards
+# (see build_windows.sh). Native builds keep the automatic step.
+set(SERUMALT_VST3_AUTO_MANIFEST TRUE)
+if(CMAKE_CROSSCOMPILING)
+    set(SERUMALT_VST3_AUTO_MANIFEST FALSE)
+endif()
+
+set(SERUMALT_FORMATS VST3)
+if(NOT WIN32)
+    list(APPEND SERUMALT_FORMATS Standalone)
+endif()
+if(APPLE)
+    list(APPEND SERUMALT_FORMATS AU)
+endif()
+
+juce_add_plugin(SerumAlt
+    VERSION ${PROJECT_VERSION}
+    COMPANY_NAME "SerumAlt Audio"
+    IS_SYNTH TRUE
+    NEEDS_MIDI_INPUT TRUE
+    NEEDS_MIDI_OUTPUT FALSE
+    IS_MIDI_EFFECT FALSE
+    EDITOR_WANTS_KEYBOARD_FOCUS FALSE
+    PLUGIN_MANUFACTURER_CODE Salt
+    PLUGIN_CODE Sera
+    BUNDLE_ID com.serumalt.SerumAlt
+    FORMATS ${SERUMALT_FORMATS}
+    PRODUCT_NAME "SerumAlt"
+    VST3_AUTO_MANIFEST ${SERUMALT_VST3_AUTO_MANIFEST})
+
+serumalt_configure_target(SerumAlt)
+
+# ---------------------------------------------------------------------------
+# MinGW cross-build: static C++/threading runtime
+# ---------------------------------------------------------------------------
+# When cross-compiling for Windows with MinGW, link libgcc / libstdc++ /
+# winpthread statically so the VST3 DLL is self-contained. Otherwise the DLL
+# imports libgcc_s_seh-1.dll, libstdc++-6.dll and libwinpthread-1.dll, none of
+# which ship with the bundle (or exist on a stock Windows host), so the host's
+# scan would fail to load the plugin. Native (Linux) builds are unaffected.
+if(MINGW)
+    target_link_options(SerumAlt_VST3 PRIVATE
+        -static-libgcc
+        -static-libstdc++
+        -static)
+endif()