Set target_family="wasm" for wasm targets

compiler/rustc_target/src/spec/mod.rs

@@ -1046,7 +1046,7 @@ pub struct TargetOptions {
     ///
     /// Common options are: "unix", "windows". Defaults to no families.
     ///
-    /// See https://doc.rust-lang.org/reference/conditional-compilation.html#target_family
+    /// See <https://doc.rust-lang.org/reference/conditional-compilation.html#target_family>.
     pub families: Vec<String>,
     /// Whether the target toolchain's ABI supports returning small structs as an integer.
     pub abi_return_struct_as_int: bool,

compiler/rustc_target/src/spec/wasm_base.rs

@@ -61,6 +61,7 @@ pub fn options() -> TargetOptions {
 
     TargetOptions {
         is_like_wasm: true,
+        families: vec!["wasm".to_string()],
 
         // we allow dynamic linking, but only cdylibs. Basically we allow a
         // final library artifact that exports some symbols (a wasm module) but

src/test/ui/cfg/cfg-family.rs

@@ -1,6 +1,6 @@
-// run-pass
+// build-pass
 // pretty-expanded FIXME #23616
-// ignore-wasm32-bare no target_family
+// ignore-wasm32-bare no bare family
 // ignore-sgx
 
 #[cfg(windows)]

src/test/ui/cfg/cfg-target-family.rs

@@ -1,5 +1,4 @@
-// run-pass
-// ignore-wasm32-bare no target_family
+// build-pass
 // ignore-sgx
 
 // pretty-expanded FIXME #23616
@@ -11,3 +10,7 @@ pub fn main() {
 #[cfg(target_family = "unix")]
 pub fn main() {
 }
+
+#[cfg(target_family="wasm")]
+pub fn main() {
+}