build(meson): use system deps when avalable

When building tests, Meson will now look for system dependencies and use
them if found. Otherwise, it will check if the submodules are cloned and
create a dependency object wrapping the include path of each external
dependency (this breaks Meson's sandbox, but the previous approach did
too). This also allows passing actual dependencies to the various build
targets instead of include paths (a bit more idiomatic).

I've also made it possible to skip the tl-optional tests when the lib is
not found, so that it is still possible to run tests even from a
tarball (i.e. no git checkout)

.gitignore

@@ -367,3 +367,6 @@ $RECYCLE.BIN/
 *.msm
 *.msp
 *.lnk
+
+# Clangd cache
+/.cache/clangd

examples/meson.build

@@ -1,4 +1,5 @@
 example_args = []
+example_args += universal_args
 example_args += devel_args
 example_overrides = []
 example_overrides += overrides

meson.build

@@ -4,6 +4,7 @@ project(
 	version: '3.0.1',
 	meson_version: '>=0.54.0',
 	license: 'MIT',
+	subproject_dir: 'external',
 	default_options: [ # https://mesonbuild.com/Builtin-options.html
 		# core options
 		'buildtype=release',
@@ -42,7 +43,7 @@ is_windows = host_machine.system() == 'windows'
 is_x64 = host_machine.cpu_family() == 'x86_64'
 is_subproject = meson.is_subproject()
 has_exceptions = get_option('cpp_eh') != 'none'
-include_dirs = include_directories('include', 'external')
+include_dir = include_directories('include')
 overrides = []
 universal_args = [] # args used in tests, examples, lib, everything
 devel_args = [] # args used in everything *but* the lib
@@ -446,8 +447,6 @@ endif
 # subdirectories
 #######################################################################################################################
 
-include_dir = include_directories('include')
-
 # Empty dependency that will be filled either in src/ or include/
 tomlplusplus_dep = dependency('', required: false)
 
@@ -459,8 +458,6 @@ endif
 
 build_tests = get_option('build_tests') and not is_subproject
 if build_tests
-	run_command('git', 'submodule', 'update', '--init', '--depth', '1', 'external/Catch2')
-	run_command('git', 'submodule', 'update', '--init', '--depth', '1', 'external/tloptional')
 	subdir('tests')
 endif
 

tests/lib_catch2.h

@@ -24,6 +24,8 @@
 
 #if __has_include(<Catch2/single_include/catch2/catch.hpp>)
 #include <Catch2/single_include/catch2/catch.hpp>
+#elif __has_include(<catch2/catch.hpp>)
+#include <catch2/catch.hpp>
 #else
 #error Catch2 is missing! You probably need to fetch submodules ("git submodule update --init --depth 1 external/Catch2")
 #endif

tests/lib_tloptional.h

@@ -17,6 +17,8 @@
 
 #if __has_include(<tloptional/include/tl/optional.hpp>)
 #include <tloptional/include/tl/optional.hpp>
+#elif __has_include(<tl/optional.hpp>)
+#include <tl/optional.hpp>
 #else
 #error TartanLlama/optional is missing! You probably need to fetch submodules ("git submodule update --init --depth 1 external/tloptional")
 #endif

tests/meson.build

@@ -26,6 +26,33 @@ test_sources = [
 	'windows_compat.cpp'
 ]
 
+test_deps = [tomlplusplus_dep]
+
+fs = import('fs')
+
+catch2_dep = dependency('catch2', required: false)
+if catch2_dep.found()
+	test_deps += catch2_dep
+elif fs.exists('..'/'external'/'Catch2'/'single_include')
+	catch2_dep = declare_dependency(include_directories: '..'/'external'/'Catch2'/'single_include')
+	test_deps += catch2_dep
+else
+	error('Catch2 is missing! You probably need to fetch submodules ("git submodule update --init --depth 1 external/Catch2"')
+endif
+
+has_tl_optional = false
+tl_optional_dep = dependency('tl-optional', required: false)
+if tl_optional_dep.found()
+	test_deps += tl_optional_dep
+	has_tl_optional = true
+elif fs.exists('..'/'external'/'tloptional'/'include')
+	tl_optional_dep = declare_dependency(include_directories: '..'/'external'/'tloptional'/'include')
+	test_deps += tl_optional_dep
+	has_tl_optional = true
+else
+	warning('tl-optional not found, skipping its tests')
+endif
+
 #######################################################################################################################
 # fast math check
 #######################################################################################################################
@@ -87,7 +114,7 @@ foreach cpp20 : cpp20_modes
 				test_args += test_base_args
 
 				single_header = (counter % 2 == 1)
-				tl_optional = (counter % 4 == 2 and exceptions and not get_option('compile_library'))
+				tl_optional = (counter % 4 == 2 and exceptions and not get_option('compile_library') and has_tl_optional)
 				address_sanitizer = (is_clang and not (single_header or tl_optional or fast_math)) and get_option('asan_tests')
 
 				if cpp20
@@ -161,9 +188,8 @@ foreach cpp20 : cpp20_modes
 					executable(
 						test_name,
 						test_sources,
-						include_directories: include_dirs,
 						cpp_args: test_args,
-						dependencies: tomlplusplus_dep,
+						dependencies: test_deps,
 						override_options: test_overrides
 					)
 				]]
@@ -203,7 +229,7 @@ endforeach
 executable(
 	'odr_test',
 	[ 'odr_test_1.cpp', 'odr_test_2.cpp' ],
-	include_directories: include_dirs,
 	cpp_args: test_base_args,
+	dependencies: tomlplusplus_dep,
 	override_options: overrides
 )

toml-test/meson.build

@@ -1,9 +1,14 @@
+tt_deps = [
+	tomlplusplus_dep,
+	dependency('nlohmann_json', fallback: ['json', 'nlohmann_json_dep'])
+]
+
 if get_option('build_tt_encoder')
 	executable(
 		'tt_encoder',
 		'tt_encoder.cpp',
 		cpp_args: devel_args,
-		include_directories: include_dirs
+		dependencies: tt_deps
 	)
 endif
 
@@ -12,6 +17,6 @@ if get_option('build_tt_decoder')
 		'tt_decoder',
 		'tt_decoder.cpp',
 		cpp_args: devel_args,
-		include_directories: include_dirs
+		dependencies: tt_deps
 	)
 endif

toml-test/tt.h

@@ -17,6 +17,8 @@
 
 #if __has_include(<json/single_include/nlohmann/json.hpp>)
 #include <json/single_include/nlohmann/json.hpp>
+#elif __has_include(<nlohmann/json.hpp>)
+#include <nlohmann/json.hpp>
 #else
 #error nlohmann/json is missing! You probably need to fetch submodules ("git submodule update --init --depth 1 external/json")
 #endif