Factor out common library flags to a function.

I assume I'll want to make more "global" changes at some point, so
rather than copying the same add_compile_options into every project,
create add_app_library() as a wrapper around add_library() which handles
the common stuff.

audio-echo/app/src/main/cpp/CMakeLists.txt

@@ -1,9 +1,9 @@
 cmake_minimum_required(VERSION 3.22.1)
 project(echo LANGUAGES C CXX)
 
-add_compile_options(-Wall -Wextra -Werror)
+include(AppLibrary)
 
-add_library(echo
+add_app_library(echo
     SHARED
     audio_main.cpp
     audio_player.cpp

base/src/main/cpp/CMakeLists.txt

@@ -1,9 +1,9 @@
 cmake_minimum_required(VERSION 3.22.1)
 project(Base LANGUAGES CXX)
 
-add_compile_options(-Wall -Werror -Wextra)
+include(AppLibrary)
 
-add_library(base
+add_app_library(base
     STATIC
     logging.cpp
 )

bitmap-plasma/app/src/main/cpp/CMakeLists.txt

@@ -1,9 +1,9 @@
 cmake_minimum_required(VERSION 3.22.1)
 project(BitmapPlasma LANGUAGES CXX)
 
-add_compile_options(-Wall -Wextra -Werror)
+include(AppLibrary)
 
-add_library(plasma SHARED plasma.cpp)
+add_app_library(plasma SHARED plasma.cpp)
 
 # Include libraries needed for plasma lib
 target_link_libraries(plasma

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidApplicationConventionPlugin.kt

@@ -30,6 +30,7 @@ class AndroidApplicationConventionPlugin : Plugin<Project> {
                     externalNativeBuild {
                         cmake {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
+                            arguments.add("-DCMAKE_MODULE_PATH=${rootDir.resolve("cmake")}")
                         }
                     }
 

build-logic/src/main/java/com/android/ndk/samples/buildlogic/AndroidLibraryConventionPlugin.kt

@@ -33,6 +33,7 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
                     externalNativeBuild {
                         cmake {
                             arguments.add("-DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON")
+                            arguments.add("-DCMAKE_MODULE_PATH=${rootDir.resolve("cmake")}")
                         }
                     }
                     ndk {

cmake/AppLibrary.cmake

@@ -0,0 +1,15 @@
+include_guard()
+
+# Wrapper for add_library which enables common options we want for all
+# libraries.
+function(add_app_library name)
+    cmake_parse_arguments(PARSE_ARGV 1 arg "" "" "")
+    add_library(${name} ${arg_UNPARSED_ARGUMENTS})
+
+    target_compile_options(${name}
+        PRIVATE
+        -Wall
+        -Wextra
+        -Werror
+    )
+endfunction()

vectorization/src/main/cpp/CMakeLists.txt

@@ -1,11 +1,10 @@
 cmake_minimum_required(VERSION 3.22.1)
 project(Vectorization LANGUAGES CXX)
 
-add_compile_options(-Wall -Wextra -Werror)
-
+include(AppLibrary)
 find_package(base REQUIRED CONFIG)
 
-add_library(app
+add_app_library(app
     SHARED
     benchmark.cpp
     jni.cpp