fix: extensions for static/shared libraries

By default use .a and .so for static and shared libs respectively.
On macOS/Darwin - use .dylib for shared libraries.
On Windows - use .lib for static and .dll for dynamic libs.

internal/pipe/build/build.go

@@ -212,34 +212,30 @@ func buildOptionsForTarget(ctx *context.Context, build config.Build, target stri
 }
 
 func extFor(target string, build config.BuildDetails) string {
+	if target == "js_wasm" {
+		return ".wasm"
+	}
+
+	// Configure the extensions for shared and static libraries - by default .so and .a respectively -
+	// with overrides for Windows (.dll for shared and .lib for static) and .dylib for macOS.
 	buildmode := build.Buildmode
-	if strings.Contains(target, "darwin") {
-		if buildmode == "c-shared" {
+
+	if buildmode == "c-shared" {
+		if strings.Contains(target, "darwin") {
 			return ".dylib"
 		}
-		if buildmode == "c-archive" {
-			return ".a"
-		}
-	}
-	if strings.Contains(target, "linux") {
-		if buildmode == "c-shared" {
-			return ".so"
-		}
-		if buildmode == "c-archive" {
-			return ".a"
-		}
-	}
-	if strings.Contains(target, "windows") {
-		if buildmode == "c-shared" {
+		if strings.Contains(target, "windows") {
 			return ".dll"
 		}
-		if buildmode == "c-archive" {
+		return ".so"
+	}
+
+	if buildmode == "c-archive" {
+		if strings.Contains(target, "windows") {
 			return ".lib"
 		}
-		return ".exe"
-	}
-	if target == "js_wasm" {
-		return ".wasm"
+		return ".a"
 	}
+
 	return ""
 }

internal/pipe/build/build_test.go

@@ -461,9 +461,12 @@ func TestExtWasm(t *testing.T) {
 }
 
 func TestExtOthers(t *testing.T) {
-	require.Empty(t, "", extFor("linux_amd64", config.BuildDetails{}))
-	require.Empty(t, "", extFor("linuxwin_386", config.BuildDetails{}))
-	require.Empty(t, "", extFor("winasdasd_sad", config.BuildDetails{}))
+	require.Equal(t, "", extFor("linux_amd64", config.BuildDetails{}))
+	require.Equal(t, "", extFor("linuxwin_386", config.BuildDetails{}))
+	require.Equal(t, "", extFor("winasdasd_sad", config.BuildDetails{}))
+	require.Equal(t, ".so", extFor("aix_amd64", config.BuildDetails{Buildmode: "c-shared"}))
+	require.Equal(t, ".a", extFor("android_386", config.BuildDetails{Buildmode: "c-archive"}))
+	require.Equal(t, ".so", extFor("winasdasd_sad", config.BuildDetails{Buildmode: "c-shared"}))
 }
 
 func TestTemplate(t *testing.T) {