cmake: make the repo consumable via add_subdirectory / FetchContent

.github/workflows/ci.yml

@@ -40,3 +40,15 @@ jobs:
 
       - name: Test
         run: ctest --test-dir build --output-on-failure --parallel
+
+      # Prove the repo still works as an embedded dependency (the path
+      # the kicad plugin repos use): the consumer project
+      # add_subdirectory()s this checkout with apps, tests and mpkit
+      # widgets defaulted OFF.
+      - name: Consumer smoke (embedded use)
+        run: |
+          cmake -S tests/consumer -B build-consumer -G Ninja \
+            -DCMAKE_BUILD_TYPE=Release -DCIRCUITCORE_DIR=$PWD
+          cmake --build build-consumer --parallel
+          ./build-consumer/consumer_smoke pdnkit/tests/fixtures/tiny_pdn.kicad_pcb
+          test ! -e build-consumer/circuitcore/pdnkit/pdnkit

CMakeLists.txt

@@ -1,6 +1,15 @@
 cmake_minimum_required(VERSION 3.20)
 project(circuitcore LANGUAGES CXX VERSION 0.1.0)
 
+# Standalone build vs embedded (add_subdirectory / FetchContent from a
+# parent project). Apps, tests and the VTK-heavy mpkit widgets default
+# OFF when embedded so a consumer gets just the libraries.
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+    set(CIRCUITCORE_TOP_LEVEL ON)
+else()
+    set(CIRCUITCORE_TOP_LEVEL OFF)
+endif()
+
 set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
@@ -75,21 +84,30 @@ if(MSVC)
     )
 endif()
 
-if(NOT CMAKE_BUILD_TYPE)
+# Only steer the build type when this is our own build; never clobber
+# a parent project's cache.
+if(CIRCUITCORE_TOP_LEVEL AND NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Release CACHE STRING "" FORCE)
 endif()
 
 option(CIRCUITCORE_BUILD_MPKIT_WIDGETS
        "Build mpkit::widgets (pulls in VTK via FetchContent, adds ~20 min)"
-       ON)
+       ${CIRCUITCORE_TOP_LEVEL})
 
-option(CIRCUITCORE_BUILD_TESTS "Build all test suites" ON)
+option(CIRCUITCORE_BUILD_TESTS "Build all test suites"
+       ${CIRCUITCORE_TOP_LEVEL})
+
+option(CIRCUITCORE_BUILD_APPS
+       "Build the GUI/CLI executables (pdnkit, sikit, emikit, studio)"
+       ${CIRCUITCORE_TOP_LEVEL})
 
 # --- Shared dependencies ---
 find_package(Qt6 REQUIRED COMPONENTS Widgets OpenGL OpenGLWidgets)
 find_package(Eigen3 REQUIRED NO_MODULE)
 find_package(spdlog REQUIRED)
-find_package(CLI11 REQUIRED)
+if(CIRCUITCORE_BUILD_APPS)
+    find_package(CLI11 REQUIRED)  # only the executables parse arguments
+endif()
 
 # Cross-compiler warning preset. GCC/Clang get the full -Wall -Wextra
 # -Wpedantic trio; MSVC gets /W4 (its /Wall is famously too noisy for
@@ -140,8 +158,9 @@ add_subdirectory(pdnkit)
 add_subdirectory(sikit)
 add_subdirectory(emikit)
 add_subdirectory(mpkit)
-add_subdirectory(studio)   # circuitcore_studio -- unified browser-tab GUI
-                            # (see sikit/MIGRATION.md)
+if(CIRCUITCORE_BUILD_APPS)
+    add_subdirectory(studio)   # circuitcore_studio -- unified browser-tab GUI
+endif()
 
 # --- Test discovery for the core libs ---
 if(CIRCUITCORE_BUILD_TESTS)

README.md

@@ -155,6 +155,26 @@ Binaries land in `build/pdnkit/pdnkit`, `build/sikit/sikit`,
 - Sikit FDTD validated against analytic stripline + planar-waveguide
   cases.
 
+## Using circuitcore as a dependency
+
+Consumable via add_subdirectory or FetchContent; apps, tests and the
+VTK-backed mpkit widgets switch OFF automatically when circuitcore is
+not the top-level project.
+
+```cmake
+include(FetchContent)
+FetchContent_Declare(circuitcore
+    GIT_REPOSITORY https://github.com/UnsignedChad/circuitcore.git
+    GIT_TAG        v0.1.0-alpha.4)
+FetchContent_MakeAvailable(circuitcore)
+
+target_link_libraries(myplugin PRIVATE pdnkit::widgets circuitcore::kicad)
+```
+
+Library targets: `circuitcore::{board,sexpr,netlist,kicad,field,ui}`,
+`pdnkit::{pi,widgets}`, `sikit::{si,widgets}`, `emikit::emi`,
+`mpkit::{mp,widgets}`. See `tests/consumer/` for a minimal consumer.
+
 ## Contributing
 
 See `CONTRIBUTING.md`. CI runs gcc-13 on Ubuntu 24.04. CODEOWNERS gates

emikit/CMakeLists.txt

@@ -8,19 +8,24 @@ add_library(emikit_emi STATIC
     emi/Masks.cpp
     emi/BoardAnalysis.cpp
 )
-target_include_directories(emikit_emi PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+add_library(emikit::emi ALIAS emikit_emi)
+target_include_directories(emikit_emi PUBLIC
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+)
 target_link_libraries(emikit_emi PUBLIC circuitcore::board)
 circuitcore_warnings(emikit_emi)
 
-add_executable(emikit
-    main.cpp
-)
-target_link_libraries(emikit PRIVATE
-    emikit_emi
-    circuitcore::kicad
-    CLI11::CLI11
-)
-circuitcore_warnings(emikit)
+if(CIRCUITCORE_BUILD_APPS)
+    add_executable(emikit
+        main.cpp
+    )
+    target_link_libraries(emikit PRIVATE
+        emikit_emi
+        circuitcore::kicad
+        CLI11::CLI11
+    )
+    circuitcore_warnings(emikit)
+endif()
 
 # emikit_validate_ti reconstructs a vendor reference dataset (TI
 # ADS8686SEVM-PDK) and compares emikits FAR-field prediction. Useful

field/CMakeLists.txt

@@ -16,7 +16,7 @@ add_library(circuitcore_field STATIC
 add_library(circuitcore::field ALIAS circuitcore_field)
 
 target_include_directories(circuitcore_field PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
 )
 
 circuitcore_warnings(circuitcore_field)

mpkit/CMakeLists.txt

@@ -40,7 +40,7 @@ add_library(mpkit_mp STATIC
 add_library(mpkit::mp ALIAS mpkit_mp)
 
 target_include_directories(mpkit_mp PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
 )
 
 target_link_libraries(mpkit_mp PUBLIC

mpkit/widgets/CMakeLists.txt

@@ -97,8 +97,8 @@ else()
     # MSVC removed that type outright; patch the branch out so the
     # diy2 fmt compiles on VS 17.10+ / VS 18 Insiders. no-op on linux
     # / older MSVC where the branch was harmless anyway.
-    include("${CMAKE_SOURCE_DIR}/cmake/patches/patch_vtk_diy2_fmt.cmake")
-    include("${CMAKE_SOURCE_DIR}/cmake/patches/patch_vtk_smp_sequential.cmake")
+    include("${circuitcore_SOURCE_DIR}/cmake/patches/patch_vtk_diy2_fmt.cmake")
+    include("${circuitcore_SOURCE_DIR}/cmake/patches/patch_vtk_smp_sequential.cmake")
 endif()  # MPKIT_USE_SYSTEM_VTK
 
 add_library(mpkit_widgets STATIC
@@ -108,7 +108,7 @@ add_library(mpkit_widgets STATIC
 add_library(mpkit::widgets ALIAS mpkit_widgets)
 
 target_include_directories(mpkit_widgets PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
 )
 
 set_target_properties(mpkit_widgets PROPERTIES

pdnkit/CMakeLists.txt

@@ -23,9 +23,10 @@ add_library(pdnkit_pi STATIC
     StackupWriter.cpp
     render/IrResultMesh.cpp
 )
+add_library(pdnkit::pi ALIAS pdnkit_pi)
 target_include_directories(pdnkit_pi PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_SOURCE_DIR}/third_party
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+    $<BUILD_INTERFACE:${circuitcore_SOURCE_DIR}/third_party>
 )
 target_link_libraries(pdnkit_pi PUBLIC
     circuitcore::board
@@ -70,8 +71,9 @@ add_library(pdnkit_widgets STATIC
 add_library(pdnkit::widgets ALIAS pdnkit_widgets)
 set_target_properties(pdnkit_widgets PROPERTIES AUTOMOC ON)
 target_include_directories(pdnkit_widgets PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_SOURCE_DIR}    # so studio can use "pdnkit/PcbCanvas.h" etc.
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+    # repo root, so studio + downstream apps can use "pdnkit/PcbCanvas.h"
+    $<BUILD_INTERFACE:${circuitcore_SOURCE_DIR}>
 )
 target_link_libraries(pdnkit_widgets PUBLIC
     circuitcore::ui
@@ -83,25 +85,27 @@ target_link_libraries(pdnkit_widgets PUBLIC
 circuitcore_warnings(pdnkit_widgets)
 
 # GUI binary. Needs the KiCad adapter to open files, plus Qt.
-add_executable(pdnkit
-    main.cpp
-    MainWindow.cpp
-)
-set_target_properties(pdnkit PROPERTIES
-    AUTOMOC ON
-    AUTOUIC ON
-    AUTORCC ON
-)
-target_link_libraries(pdnkit PRIVATE
-    pdnkit::widgets
-    pdnkit_pi
-    circuitcore::kicad
-    Qt6::Widgets
-    Qt6::OpenGLWidgets
-    Qt6::OpenGL
-    CLI11::CLI11
-)
-circuitcore_warnings(pdnkit)
+if(CIRCUITCORE_BUILD_APPS)
+    add_executable(pdnkit
+        main.cpp
+        MainWindow.cpp
+    )
+    set_target_properties(pdnkit PROPERTIES
+        AUTOMOC ON
+        AUTOUIC ON
+        AUTORCC ON
+    )
+    target_link_libraries(pdnkit PRIVATE
+        pdnkit::widgets
+        pdnkit_pi
+        circuitcore::kicad
+        Qt6::Widgets
+        Qt6::OpenGLWidgets
+        Qt6::OpenGL
+        CLI11::CLI11
+    )
+    circuitcore_warnings(pdnkit)
+endif()
 
 if(CIRCUITCORE_BUILD_TESTS)
     add_subdirectory(tests)

sikit/CMakeLists.txt

@@ -56,9 +56,10 @@ add_library(sikit_si STATIC
     render/Mesher3D.cpp
     render/GlbLoader.cpp
 )
+add_library(sikit::si ALIAS sikit_si)
 target_include_directories(sikit_si PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_SOURCE_DIR}/third_party
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+    $<BUILD_INTERFACE:${circuitcore_SOURCE_DIR}/third_party>
 )
 target_link_libraries(sikit_si
     PUBLIC
@@ -89,8 +90,9 @@ add_library(sikit_widgets STATIC
 add_library(sikit::widgets ALIAS sikit_widgets)
 set_target_properties(sikit_widgets PROPERTIES AUTOMOC ON)
 target_include_directories(sikit_widgets PUBLIC
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_SOURCE_DIR}    # so studio can use "sikit/EyeWindow.h" etc.
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+    # repo root, so studio + downstream apps can use "sikit/EyeWindow.h"
+    $<BUILD_INTERFACE:${circuitcore_SOURCE_DIR}>
 )
 target_link_libraries(sikit_widgets PUBLIC
     sikit_si
@@ -102,26 +104,28 @@ target_link_libraries(sikit_widgets PUBLIC
 circuitcore_warnings(sikit_widgets)
 
 # GUI binary. Needs the KiCad adapter to open files, plus Qt.
-add_executable(sikit
-    main.cpp
-    MainWindow.cpp
-)
-set_target_properties(sikit PROPERTIES
-    AUTOMOC ON
-    AUTOUIC ON
-    AUTORCC ON
-)
-target_link_libraries(sikit PRIVATE
-    sikit_si
-    sikit::widgets
-    circuitcore::ui      # PcbCanvas now subclasses circuitcore::ui::PcbCanvas
-    circuitcore::kicad
-    Qt6::Widgets
-    Qt6::OpenGLWidgets
-    Qt6::OpenGL
-    CLI11::CLI11
-)
-circuitcore_warnings(sikit)
+if(CIRCUITCORE_BUILD_APPS)
+    add_executable(sikit
+        main.cpp
+        MainWindow.cpp
+    )
+    set_target_properties(sikit PROPERTIES
+        AUTOMOC ON
+        AUTOUIC ON
+        AUTORCC ON
+    )
+    target_link_libraries(sikit PRIVATE
+        sikit_si
+        sikit::widgets
+        circuitcore::ui      # PcbCanvas subclasses circuitcore::ui::PcbCanvas
+        circuitcore::kicad
+        Qt6::Widgets
+        Qt6::OpenGLWidgets
+        Qt6::OpenGL
+        CLI11::CLI11
+    )
+    circuitcore_warnings(sikit)
+endif()
 
 if(CIRCUITCORE_BUILD_TESTS)
     add_subdirectory(tests)

tests/consumer/CMakeLists.txt

@@ -0,0 +1,28 @@
+# Standalone smoke test that circuitcore works as an embedded dependency
+# (add_subdirectory / FetchContent), which is how the kicad plugin repos
+# consume it. NOT part of the circuitcore build -- CI configures this
+# directory as its own project:
+#
+#   cmake -S tests/consumer -B build-consumer -DCIRCUITCORE_DIR=$PWD
+#   cmake --build build-consumer
+#   ./build-consumer/consumer_smoke pdnkit/tests/fixtures/tiny_pdn.kicad_pcb
+cmake_minimum_required(VERSION 3.20)
+project(circuitcore_consumer LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 23)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+if(NOT CIRCUITCORE_DIR)
+    message(FATAL_ERROR "pass -DCIRCUITCORE_DIR=<circuitcore checkout>")
+endif()
+
+# Embedded: CIRCUITCORE_BUILD_{APPS,TESTS,MPKIT_WIDGETS} all default OFF,
+# so this configure must not require CLI11, Catch2 or VTK.
+add_subdirectory(${CIRCUITCORE_DIR} circuitcore)
+
+add_executable(consumer_smoke main.cpp)
+target_link_libraries(consumer_smoke PRIVATE
+    circuitcore::kicad
+    pdnkit::widgets   # widest closure: pi engine + ui + Qt
+    emikit::emi
+)

tests/consumer/main.cpp

@@ -0,0 +1,36 @@
+// Embedded-consumption smoke test. Exercises every include style a
+// plugin repo will use: prefixed core headers, bare kit-engine headers,
+// and the repo-root widgets headers (compile-only -- no QApplication).
+#include <cmath>
+#include <cstdio>
+
+#include "circuitcore/board/Board.h"
+#include "circuitcore/formats/kicad/PcbParser.h"
+#include "emi/Masks.h"
+#include "pdnkit/AnalysisPanel.h"
+#include "pi/TargetZ.h"
+
+int main(int argc, char** argv) {
+    if (argc < 2) {
+        std::fprintf(stderr, "usage: consumer_smoke <board.kicad_pcb>\n");
+        return 2;
+    }
+
+    auto board =
+        circuitcore::formats::kicad::PcbParser::parse_file(argv[1]);
+    if (!board) {
+        std::fprintf(stderr, "parse failed\n");
+        return 1;
+    }
+    std::printf("parsed: %zu nets, %zu zones\n", board->nets.size(),
+                board->zones.size());
+    if (board->nets.empty()) return 1;
+
+    const pdnkit::pi::TargetZSpec spec{3.3, 0.05, 1.0};
+    const double z = pdnkit::pi::target_impedance_flat(spec);
+    std::printf("target z: %.4f ohm\n", z);
+    if (std::abs(z - 0.165) > 1e-9) return 1;
+
+    std::printf("consumer smoke ok\n");
+    return 0;
+}

ui/CMakeLists.txt

@@ -33,7 +33,7 @@ target_include_directories(circuitcore_ui PUBLIC
 )
 # earcut.hpp lives under third_party/ at the repo root (header-only).
 target_include_directories(circuitcore_ui PRIVATE
-    ${CMAKE_SOURCE_DIR}/third_party
+    ${circuitcore_SOURCE_DIR}/third_party
 )
 
 target_link_libraries(circuitcore_ui