Support linking against external libraries with Chapel's CMake support

doc/rst/usingchapel/compiling.rst

@@ -203,3 +203,41 @@ will build a release version of the program:
    mkdir build && cd build
    cmake .. -DCMAKE_BUILD_TYPE=release
    cmake --build .
+
+
+Additional compilation flags for compiling the Chapel code can be added using
+``target_link_options``. For example, this snippet limits the amount of
+optimization done by the backend compiler to speed up compilation times.
+
+.. code-block:: cmake
+
+   target_link_options(myProgram PRIVATE --ccflags -O1)
+
+This also means that projects using a mix of C and Chapel code may need to
+specify arguments twice. For example, this snippet shows a project that uses
+both Chapel and C code:
+
+.. code-block:: cmake
+
+   add_executable(main)
+   target_sources(main PRIVATE myChapelProgram.chpl src/c_source_file.c)
+   set_target_properties(main PROPERTIES LINKER_LANGUAGE CHPL)
+
+   # used by C compiler
+   target_include_directories(main PRIVATE include)
+   # used by Chapel compiler
+   target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
+
+
+In larger projects, it may be useful to compile the C code separately. This can
+be done by creating a library target for the C code and linking it to the Chapel
+code:
+
+.. code-block:: cmake
+
+   add_library(myCCode src/c_source_file.c)
+   target_include_directories(myCCode PRIVATE include)
+
+   add_executable(myChapelProgram main.chpl)
+   target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
+   target_link_libraries(myChapelProgram PRIVATE myCCode)

test/cmake/linkWithC/CMakeLists.txt

@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.21.1)
+
+find_package(chpl REQUIRED)
+
+project(linkWithC LANGUAGES CHPL C)
+message(STATUS "Using chpl: ${CMAKE_CHPL_COMPILER}")
+
+
+add_executable(main)
+target_sources(main PRIVATE main.chpl src/adder.c)
+set_target_properties(main PROPERTIES LINKER_LANGUAGE CHPL)
+
+# used by C compiler
+target_include_directories(main PRIVATE include)
+# used by Chapel compiler
+target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
+
+install(TARGETS main DESTINATION ".")

test/cmake/linkWithC/include/adder.h

@@ -0,0 +1,6 @@
+#ifndef MY_ADDER_H
+#define MY_ADDER_H
+
+int add(int a, int b);
+
+#endif

test/cmake/linkWithC/main.chpl

@@ -0,0 +1,7 @@
+use CTypes;
+require "adder.h";
+extern proc add(a: c_int, b: c_int): c_int;
+proc main() {
+  writeln("Hello, world!");
+  writeln("1 + 2 = ", add(1, 2));
+}

test/cmake/linkWithC/src/adder.c

@@ -0,0 +1,5 @@
+#include <adder.h>
+
+int add(int a, int b) {
+  return a + b;
+}

test/cmake/sharedLib/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.21.1)
+
+find_package(chpl REQUIRED)
+
+project(sharedLib LANGUAGES CHPL C)
+message(STATUS "Using chpl: ${CMAKE_CHPL_COMPILER}")
+
+
+add_library(adder SHARED)
+target_sources(adder PRIVATE src/adder.c)
+target_include_directories(adder PUBLIC include)
+install(TARGETS adder DESTINATION "lib")
+
+
+add_executable(main)
+target_sources(main PRIVATE main.chpl)
+target_link_libraries(main adder)
+target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
+install(TARGETS main DESTINATION "bin")

test/cmake/sharedLib/include/adder.h

@@ -0,0 +1,6 @@
+#ifndef MY_ADDER_H
+#define MY_ADDER_H
+
+int add(int a, int b);
+
+#endif

test/cmake/sharedLib/main.c

@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include "adder.h"
+int main() {
+    int a = 1;
+    int b = 2;
+    int c = add(a, b);
+    printf("a + b = %d\n", c);
+}

test/cmake/sharedLib/main.chpl

@@ -0,0 +1,7 @@
+use CTypes;
+require "adder.h";
+extern proc add(a: c_int, b: c_int): c_int;
+proc main() {
+  writeln("Hello, world!");
+  writeln("1 + 2 = ", add(1, 2));
+}

test/cmake/sharedLib/src/adder.c

@@ -0,0 +1,5 @@
+#include <adder.h>
+
+int add(int a, int b) {
+  return a + b;
+}

test/cmake/staticLib/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.21.1)
+
+find_package(chpl REQUIRED)
+
+project(staticLib LANGUAGES CHPL C)
+message(STATUS "Using chpl: ${CMAKE_CHPL_COMPILER}")
+
+
+add_library(adder STATIC)
+target_sources(adder PRIVATE src/adder.c)
+target_include_directories(adder PUBLIC include)
+install(TARGETS adder DESTINATION "lib")
+
+
+add_executable(main)
+target_sources(main PRIVATE main.chpl)
+target_link_libraries(main adder)
+target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
+install(TARGETS main DESTINATION "bin")

test/cmake/staticLib/include/adder.h

@@ -0,0 +1,6 @@
+#ifndef MY_ADDER_H
+#define MY_ADDER_H
+
+int add(int a, int b);
+
+#endif

test/cmake/staticLib/main.chpl

@@ -0,0 +1,7 @@
+use CTypes;
+require "adder.h";
+extern proc add(a: c_int, b: c_int): c_int;
+proc main() {
+  writeln("Hello, world!");
+  writeln("1 + 2 = ", add(1, 2));
+}

test/cmake/staticLib/src/adder.c

@@ -0,0 +1,5 @@
+#include <adder.h>
+
+int add(int a, int b) {
+  return a + b;
+}

test/cmake/sub_test

@@ -119,6 +119,8 @@ def run_builds(d):
             continue
         run_build(subdir, "Debug")
         run_build(subdir, "Release")
+        run_build(subdir, "RelWithDebInfo")
+        run_build(subdir, "MinSizeRel")
 
 
 def main():

util/cmake/CMakeCHPLInformation.cmake

@@ -17,11 +17,12 @@
 
 
 # TODO: this is a hack, how do we tell cmake that we can't compile to object files?
+# TODO: how do we respect <DEFINES> and <INCLUDES>, CMake will only fill that in for CMAKE_*_COMPILER_OBJECT
 set(CMAKE_CHPL_COMPILE_OBJECT "test -f <OBJECT> || ln -s <SOURCE> <OBJECT>")
-set(CMAKE_CHPL_LINK_EXECUTABLE "<CMAKE_CHPL_COMPILER> -o <TARGET> <OBJECTS> <FLAGS> <LINK_FLAGS>")
-# <COMPILE_FLAGS> doesn't work on link step
+set(CMAKE_CHPL_LINK_EXECUTABLE "<CMAKE_CHPL_COMPILER> -o <TARGET> <OBJECTS> <FLAGS> <LINK_FLAGS> <LINK_LIBRARIES>")
 
 # TODO: support --library directly to build Chapel shared libs for interoperability
+# CMAKE_*_CREATE_SHARED_LIBRARY
 
 set(CMAKE_CHPL_SOURCE_FILE_EXTENSIONS chpl)