dl: add a complete tested shared library generation/usage example

.github/workflows/ci.yml

@@ -516,22 +516,13 @@ jobs:
   windows-tcc:
     runs-on: windows-2019
     timeout-minutes: 30
-    # We are simulating a user with no cc installed.
-    # This way, v's cc detection on Windows is also tested.
-    # env:
-    #   VFLAGS: -cc tcc
+    env:
+         VFLAGS: -cc tcc
     steps:
     - uses: actions/checkout@v2
-    #- uses: actions/setup-node@v1
-    #  with:
-    #    node-version: 12.x
-    - name: Build
-      # We need to move gcc and msvc, so that V can't find an existing C compiler and downloads tcc
+    - name: Build with make.bat -tcc
       run: |
-        'for /f "usebackq tokens=*" %i in (`where gcc.exe`) do move /Y "%i" "%i.old"'     | cmd
-        'for /f "usebackq tokens=*" %i in (`where vswhere.exe`) do move /Y "%i" "%i.old"' | cmd
-        move "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe.old"
-        .\make.bat
+        .\make.bat -tcc
     - name: Test new v.c
       run: .\v.exe -o v.c cmd/v && .\thirdparty\tcc\tcc.exe -Werror -w -ladvapi32 -bt10 v.c
     - name: Install dependencies

vlib/dl/dl_nix.c.v

@@ -1,11 +1,10 @@
 module dl
 
 #include <dlfcn.h>
-
 pub const (
 	rtld_now  = C.RTLD_NOW
 	rtld_lazy = C.RTLD_LAZY
-	dl_ext = '.so'
+	dl_ext    = get_shared_library_extension()
 )
 
 fn C.dlopen(filename charptr, flags int) voidptr
@@ -28,3 +27,14 @@ pub fn close(handle voidptr) bool {
 pub fn sym(handle voidptr, symbol string) voidptr {
 	return C.dlsym(handle, symbol.str)
 }
+
+pub fn get_shared_library_extension() string {
+	mut res := '.so'
+	$if macos {
+		res = '.dylib'
+	}
+	$if windows {
+		res = '.dll'
+	}
+	return res
+}

vlib/dl/example/library.v

@@ -0,0 +1,10 @@
+module library
+
+[export: 'add_1']
+pub fn add_1(x int, y int) int {
+	return my_private_function(x + y)
+}
+
+fn my_private_function(x int) int {
+	return 1 + x
+}

vlib/dl/example/use.v

@@ -0,0 +1,17 @@
+module main
+
+import os
+import dl
+
+type FNAdder = fn (int, int) int
+
+fn main() {
+	library_file_path := os.join_path(os.getwd(), 'library${dl.dl_ext}')
+	handle := dl.open(library_file_path, dl.rtld_lazy)
+	eprintln('handle: ${ptr_str(handle)}')
+	mut f := &FNAdder(0)
+	f = dl.sym(handle, 'add_1')
+	eprintln('f: ${ptr_str(f)}')
+	res := f(1, 2)
+	eprintln('res: $res')
+}

vlib/dl/example/use_test.v

@@ -0,0 +1,52 @@
+module main
+
+import os
+import dl
+
+const (
+	vexe              = os.real_path(os.getenv('VEXE'))
+	cfolder           = os.dir(@FILE)
+	so_ext            = dl.dl_ext
+	library_file_name = os.join_path(cfolder, 'library$so_ext')
+)
+
+fn test_vexe() {
+	eprintln('vexe: $vexe')
+	assert vexe != ''
+	eprintln('os.executable: ' + os.executable())
+	eprintln('@FILE: ' + @FILE)
+	eprintln('cfolder: $cfolder')
+	eprintln('so_ext: $so_ext')
+	eprintln('library_file_name: $library_file_name')
+}
+
+fn test_can_compile_library() {
+	os.chdir(cfolder)
+	os.rm(library_file_name)
+	res := v_compile('-d no_backtrace -o library -shared library.v')
+	eprintln('res: $res')
+	assert os.is_file(library_file_name)
+}
+
+fn test_can_compile_main_program() {
+	os.chdir(cfolder)
+	assert os.is_file(library_file_name)
+	result := v_compile('run use.v')
+	eprintln('result: $result')
+	assert result.output.contains('res: 4')
+	os.rm(library_file_name)
+}
+
+fn v_compile(vopts string) os.Result {
+	cmd := '"$vexe" -showcc $vopts'
+	eprintln('>>> v_compile cmd: $cmd')
+	res := os.exec(cmd) or { panic(err) }
+	eprintln('>>> v_compile res: $res')
+	// assert res.exit_code == 0
+	$if !windows {
+		os.system('dir $cfolder -a -l')
+	} $else {
+		os.system('dir $cfolder /a')
+	}
+	return res
+}

vlib/v/builder/cc.v

@@ -267,15 +267,17 @@ fn (mut v Builder) cc() {
 		// linux_host := os.user_os() == 'linux'
 		v.log('cc() isprod=$v.pref.is_prod outname=$v.pref.out_name')
 		if v.pref.is_shared {
+			mut shared_postfix := '.so'
+			$if macos {
+				shared_postfix = '.dylib'
+			} $else $if windows {
+				shared_postfix = '.dll'
+			}
+			if !v.pref.out_name.ends_with(shared_postfix) {
+				v.pref.out_name += shared_postfix
+			}
 			linker_flags << '-shared'
 			args << '-fPIC' // -Wl,-z,defs'
-			$if macos {
-				v.pref.out_name += '.dylib'
-			} $else $if windows {
-				v.pref.out_name += '.dll'
-			} $else {
-				v.pref.out_name += '.so'
-			}
 		}
 		if v.pref.is_bare {
 			args << '-fno-stack-protector'