Add target_env = "p1" to the wasm32-wasip1 target

This commit sets the `target_env` key for the
`wasm32-wasi{,p1,p1-threads}` targets to the string `"p1"`. This mirrors
how the `wasm32-wasip2` target has `target_env = "p2"`. The intention of
this is to more easily detect each target in downstream crates to enable
adding custom code per-target.

cc #125803

compiler/rustc_target/src/spec/targets/wasm32_wasip1.rs

@@ -18,6 +18,7 @@ pub fn target() -> Target {
     let mut options = base::wasm::options();
 
     options.os = "wasi".into();
+    options.env = "p1".into();
     options.add_pre_link_args(LinkerFlavor::WasmLld(Cc::Yes), &["--target=wasm32-wasi"]);
 
     options.pre_link_objects_self_contained = crt_objects::pre_wasi_self_contained();

compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs

@@ -13,6 +13,7 @@ pub fn target() -> Target {
     let mut options = base::wasm::options();
 
     options.os = "wasi".into();
+    options.env = "p1".into();
 
     options.add_pre_link_args(
         LinkerFlavor::WasmLld(Cc::No),

src/doc/rustc/src/platform-support/wasm32-wasip1-threads.md

@@ -150,3 +150,15 @@ or another engine that supports `wasi-threads` is installed and can be found in
 5. Apply such [a change](https://github.com/g0djan/rust/compare/godjan/wasi-threads...g0djan:rust:godjan/wasi-run-ui-tests?expand=1) with an engine from the step 1.
 6. Run `./x.py test --target wasm32-wasip1-threads tests/ui` and save the list of failed tests.
 7. For both lists of failed tests run `cat list | sort > sorted_list` and compare it with `diff sorted_list1 sorted_list2`.
+
+## Conditionally compiling code
+
+It's recommended to conditionally compile code for this target with:
+
+```
+#[cfg(all(target_os = "wasi", target_env = "p1", target_feature = "atomics"))]
+```
+
+Prior to Rust 1.80 the `target_env = "p1"` key was not set. Currently the
+`target_feature = "atomics"` is Nightly-only. Note that the precise `#[cfg]`
+necessary to detect this target may change as the target becomes more stable.

src/doc/rustc/src/platform-support/wasm32-wasip1.md

@@ -121,3 +121,14 @@ can be tested locally, for example, with:
 ```text
 ./x.py test --target wasm32-wasip1 tests/ui
 ```
+
+## Conditionally compiling code
+
+It's recommended to conditionally compile code for this target with:
+
+```
+#[cfg(all(target_os = "wasi", target_env = "p1"))]
+```
+
+Note that the `target_env = "p1"` condition first appeared in Rust 1.80. Prior
+to Rust 1.80 the `target_env` condition was not set.

src/doc/rustc/src/platform-support/wasm32-wasip2.md

@@ -53,3 +53,11 @@ This target is not tested in CI at this time. Locally it can be tested with a
 ```text
 ./x.py test --target wasm32-wasip2 tests/ui
 ```
+
+## Conditionally compiling code
+
+It's recommended to conditionally compile code for this target with:
+
+```
+#[cfg(all(target_os = "wasi", target_env = "p2"))]
+```