Partially support building and locating wasm proc-macros

compiler/rustc_driver_impl/src/lib.rs

@@ -659,6 +659,7 @@ fn print_crate_info(
                 println_info!("{}", targets.join("\n"));
             }
             HostTuple => println_info!("{}", rustc_session::config::host_tuple()),
+            WasmProcMacroTuple => println_info!("{}", sess.wasm_proc_macro_tuple),
             Sysroot => println_info!("{}", sess.opts.sysroot.path().display()),
             TargetLibdir => println_info!("{}", sess.target_tlib_path.dir.display()),
             TargetSpecJson => {

compiler/rustc_metadata/src/creader.rs

@@ -719,13 +719,21 @@ impl CStore {
             // Load the proc macro crate for the host
             proc_macro_locator.for_proc_macro(sess, path_kind);
 
-            let Some(host_result) =
+            if let Some(host_result) =
                 self.load(&mut proc_macro_locator, &mut CrateRejections::default())?
-            else {
-                return Ok(None);
-            };
+            {
+                Ok(Some((host_result, None)))
+            } else if sess.opts.unstable_opts.wasm_proc_macros {
+                // Load the proc macro crate for wasm
+                proc_macro_locator.for_wasm_proc_macro(sess, path_kind);
 
-            Ok(Some((host_result, None)))
+                match self.load(&mut proc_macro_locator, &mut CrateRejections::default())? {
+                    Some(host_result) => Ok(Some((host_result, None))),
+                    None => Ok(None),
+                }
+            } else {
+                Ok(None)
+            }
         }
     }
 

compiler/rustc_metadata/src/locator.rs

@@ -360,6 +360,14 @@ impl<'a> CrateLocator<'a> {
         self.path_kind = path_kind;
     }
 
+    pub(crate) fn for_wasm_proc_macro(&mut self, sess: &'a Session, path_kind: PathKind) {
+        self.is_proc_macro = true;
+        self.target = &sess.wasm_proc_macro_target;
+        self.tuple = sess.wasm_proc_macro_tuple.clone();
+        self.filesearch = sess.wasm_proc_macro_filesearch();
+        self.path_kind = path_kind;
+    }
+
     pub(crate) fn maybe_load_library_crate(
         &self,
         crate_rejections: &mut CrateRejections,
@@ -734,6 +742,8 @@ impl<'a> CrateLocator<'a> {
         &self,
         crate_rejections: &mut CrateRejections,
     ) -> Result<Option<Library>, CrateError> {
+        debug!("find_commandline_library {}", self.crate_name);
+
         // First, filter out all libraries that look suspicious. We only accept
         // files which actually exist that have the correct naming scheme for
         // rlibs/dylibs.

compiler/rustc_session/src/config/print_request.rs

@@ -48,6 +48,7 @@ pub enum PrintKind {
     TargetSpecJson,
     TargetSpecJsonSchema,
     TlsModels,
+    WasmProcMacroTuple,
     // tidy-alphabetical-end
 }
 
@@ -82,6 +83,7 @@ impl PrintKind {
             TargetSpecJson => "target-spec-json",
             TargetSpecJsonSchema => "target-spec-json-schema",
             TlsModels => "tls-models",
+            WasmProcMacroTuple => "wasm-proc-macro-tuple",
             // tidy-alphabetical-end
         }
     }
@@ -118,6 +120,7 @@ impl PrintKind {
             SupportedCrateTypes => false,
             TargetSpecJson => false,
             TargetSpecJsonSchema => false,
+            WasmProcMacroTuple => false,
         }
     }
 

compiler/rustc_session/src/output.rs

@@ -137,6 +137,13 @@ pub fn invalid_output_for_target(sess: &Session, crate_type: CrateType) -> bool
             return true;
         }
     }
+    if crate_type == CrateType::ProcMacro {
+        if sess.opts.target_triple == sess.wasm_proc_macro_tuple
+            && sess.opts.unstable_opts.wasm_proc_macros
+        {
+            return false;
+        }
+    }
     if let CrateType::ProcMacro | CrateType::Dylib = crate_type
         && sess.target.only_cdylib
     {

compiler/rustc_session/src/session.rs

@@ -327,6 +327,8 @@ impl PointerAuthConfig {
 pub struct Session {
     pub target: Target,
     pub host: Target,
+    pub wasm_proc_macro_tuple: TargetTuple,
+    pub wasm_proc_macro_target: Target,
     pub opts: config::Options,
     pub target_tlib_path: SearchPath,
     pub psess: ParseSess,
@@ -395,6 +397,7 @@ pub struct Session {
 
     target_filesearch: Arc<FileSearch>,
     host_filesearch: Arc<FileSearch>,
+    wasm_proc_macro_filesearch: Option<Arc<FileSearch>>,
 
     /// The names of intrinsics that the current codegen backend replaces
     /// with its own implementations.
@@ -664,6 +667,9 @@ impl Session {
     pub fn host_filesearch(&self) -> &filesearch::FileSearch {
         &self.host_filesearch
     }
+    pub fn wasm_proc_macro_filesearch(&self) -> &filesearch::FileSearch {
+        self.wasm_proc_macro_filesearch.as_ref().expect("wasm_filesearch not set")
+    }
 
     /// Returns a list of directories where target-specific tool binaries are located. Some fallback
     /// directories are also returned, for example if `--sysroot` is used but tools are missing
@@ -1295,6 +1301,19 @@ pub fn build_session(
         dcx.handle().warn(warning)
     }
 
+    let wasm_proc_macro_tuple = TargetTuple::from_tuple("wasm32-wasip2");
+    let (wasm_proc_macro_target, target_warnings) = Target::search(
+        &wasm_proc_macro_tuple,
+        sopts.sysroot.path(),
+        sopts.unstable_opts.unstable_options,
+    )
+    .unwrap_or_else(|e| {
+        dcx.handle().fatal(format!("Error loading wasm proc-macro target specification: {e}"))
+    });
+    for warning in target_warnings.warning_messages() {
+        dcx.handle().warn(warning)
+    }
+
     let self_profiler = if let SwitchWithOptPath::Enabled(ref d) = sopts.unstable_opts.self_profile
     {
         let directory = if let Some(directory) = d { directory } else { std::path::Path::new(".") };
@@ -1323,6 +1342,8 @@ pub fn build_session(
     // FIXME use host sysroot?
     let host_tlib_path = SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), host_triple);
     let target_tlib_path = SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), target_triple);
+    let wasm_proc_macro_tlib_path =
+        SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), wasm_proc_macro_tuple.tuple());
 
     let prof = SelfProfilerRef::new(
         self_profiler,
@@ -1352,6 +1373,16 @@ pub fn build_session(
             sopts.unstable_opts.implicit_sysroot_deps,
         ))
     };
+    let wasm_proc_macro_filesearch = if sopts.unstable_opts.wasm_proc_macros {
+        Some(Arc::new(FileSearch::new(
+            &sopts.search_paths,
+            &wasm_proc_macro_tlib_path,
+            &wasm_proc_macro_target,
+            sopts.unstable_opts.implicit_sysroot_deps,
+        )))
+    } else {
+        None
+    };
 
     let timings = TimingSectionHandler::new(sopts.json_timings);
 
@@ -1361,6 +1392,8 @@ pub fn build_session(
     let sess = Session {
         target,
         host,
+        wasm_proc_macro_tuple,
+        wasm_proc_macro_target,
         opts: sopts,
         target_tlib_path,
         psess,
@@ -1384,6 +1417,7 @@ pub fn build_session(
         file_depinfo: Default::default(),
         target_filesearch,
         host_filesearch,
+        wasm_proc_macro_filesearch,
         replaced_intrinsics: FxHashSet::default(), // filled by `run_compiler`
         fallback_intrinsics: FxHashSet::default(), // filled by `run_compiler`
         thin_lto_supported: true,                  // filled by `run_compiler`

src/doc/unstable-book/src/compiler-flags/print-wasm-proc-macro-tuple.md

@@ -0,0 +1,13 @@
+# `print=wasm-proc-macro-tuple`
+
+The tracking issue for this feature is: [#160389](https://github.com/rust-lang/rust/issues/160389).
+
+------------------------
+
+This option of the `--print` flag produces the target for which wasm proc-macros should be compiled.
+
+Intended to be used like this:
+
+```bash
+rustc --print=wasm-proc-macro-tuple -Zunstable-options
+```

src/tools/compiletest/src/runtest.rs

@@ -91,14 +91,16 @@ fn disable_error_reporting<F: FnOnce() -> R, R>(f: F) -> R {
 }
 
 /// The platform-specific library name
-fn get_lib_name(name: &str, aux_type: AuxType) -> Option<String> {
+fn get_lib_name(name: &str, aux_type: AuxType, wasm_proc_macros: bool) -> Option<String> {
     match aux_type {
         AuxType::Bin => None,
         // In some cases (e.g. MUSL), we build a static
         // library, rather than a dynamic library.
         // In this case, the only path we can pass
         // with '--extern-meta' is the '.rlib' file
         AuxType::Lib => Some(format!("lib{name}.rlib")),
+        // FIXME maybe use `rustc --print file-names` instead?
+        AuxType::ProcMacro if wasm_proc_macros => Some(format!("{name}.wasm")),
         AuxType::Dylib | AuxType::ProcMacro => Some(dylib_name(name)),
     }
 }
@@ -1248,7 +1250,8 @@ impl<'test> TestCx<'test> {
                           aux_name: &str,
                           aux_path: &str,
                           aux_type: AuxType| {
-            let lib_name = get_lib_name(&path_to_crate_name(aux_path), aux_type);
+            let lib_name =
+                get_lib_name(&path_to_crate_name(aux_path), aux_type, self.config.wasm_proc_macros);
             if let Some(lib_name) = lib_name {
                 let modifiers_and_name = match extern_modifiers {
                     Some(modifiers) => format!("{modifiers}:{aux_name}"),
@@ -1279,7 +1282,11 @@ impl<'test> TestCx<'test> {
         // to `-Zcodegen-backend` when compiling the test file.
         if let Some(aux_file) = &self.props.aux.codegen_backend {
             let aux_type = self.build_auxiliary(aux_file, aux_dir, None);
-            if let Some(lib_name) = get_lib_name(aux_file.trim_end_matches(".rs"), aux_type) {
+            if let Some(lib_name) = get_lib_name(
+                aux_file.trim_end_matches(".rs"),
+                aux_type,
+                self.config.wasm_proc_macros,
+            ) {
                 let lib_path = aux_dir.join(&lib_name);
                 rustc.arg(format!("-Zcodegen-backend={}", lib_path));
             }

tests/run-make/print-request-help-stable-unstable/help-diff.diff

@@ -2,6 +2,6 @@
  error: unknown print request: `xxx`
    |
 -  = help: valid print requests are: `calling-conventions`, `cfg`, `code-models`, `crate-name`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `tls-models`
-+  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`
++  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`, `wasm-proc-macro-tuple`
    = help: for more information, see the rustc book: https://doc.rust-lang.org/rustc/command-line-arguments.html#--print-print-compiler-information
 

tests/run-make/print-request-help-stable-unstable/unstable-invalid-print-request-help.err

@@ -1,5 +1,5 @@
 error: unknown print request: `xxx`
   |
-  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`
+  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`, `wasm-proc-macro-tuple`
   = help: for more information, see the rustc book: https://doc.rust-lang.org/rustc/command-line-arguments.html#--print-print-compiler-information
 

tests/run-make/rustc-help/help-v.stdout

@@ -43,7 +43,7 @@ Options:
         --print <INFO>[=<FILE>]
                         Compiler information to print on stdout (or to a file)
                         INFO may be one of
-                        <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models>.
+                        <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models|wasm-proc-macro-tuple>.
     -g                  Equivalent to -C debuginfo=2
     -O                  Equivalent to -C opt-level=3
     -o <FILENAME>       Write output to FILENAME

tests/run-make/rustc-help/help.stdout

@@ -43,7 +43,7 @@ Options:
         --print <INFO>[=<FILE>]
                         Compiler information to print on stdout (or to a file)
                         INFO may be one of
-                        <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models>.
+                        <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models|wasm-proc-macro-tuple>.
     -g                  Equivalent to -C debuginfo=2
     -O                  Equivalent to -C opt-level=3
     -o <FILENAME>       Write output to FILENAME

tests/ui/compile-flags/invalid/print-without-arg.stderr

@@ -3,5 +3,5 @@ error: Argument to option 'print' missing
            --print <INFO>[=<FILE>]
                                Compiler information to print on stdout (or to a file)
                                INFO may be one of
-                               <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models>.
+                               <all-target-specs-json|backend-has-mnemonic|backend-has-zstd|calling-conventions|cfg|check-cfg|code-models|crate-name|crate-root-lint-levels|deployment-target|file-names|host-tuple|link-args|native-static-libs|relocation-models|split-debuginfo|stack-protector-strategies|supported-crate-types|sysroot|target-cpus|target-features|target-libdir|target-list|target-spec-json|target-spec-json-schema|tls-models|wasm-proc-macro-tuple>.
 

tests/ui/compile-flags/invalid/print.stderr

@@ -1,5 +1,5 @@
 error: unknown print request: `yyyy`
   |
-  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`
+  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`, `wasm-proc-macro-tuple`
   = help: for more information, see the rustc book: https://doc.rust-lang.org/rustc/command-line-arguments.html#--print-print-compiler-information
 

tests/ui/print-request/print-lints-help.stderr

@@ -1,6 +1,6 @@
 error: unknown print request: `lints`
   |
-  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`
+  = help: valid print requests are: `all-target-specs-json`, `backend-has-mnemonic`, `backend-has-zstd`, `calling-conventions`, `cfg`, `check-cfg`, `code-models`, `crate-name`, `crate-root-lint-levels`, `deployment-target`, `file-names`, `host-tuple`, `link-args`, `native-static-libs`, `relocation-models`, `split-debuginfo`, `stack-protector-strategies`, `supported-crate-types`, `sysroot`, `target-cpus`, `target-features`, `target-libdir`, `target-list`, `target-spec-json`, `target-spec-json-schema`, `tls-models`, `wasm-proc-macro-tuple`
   = help: use `-Whelp` to print a list of lints
   = help: for more information, see the rustc book: https://doc.rust-lang.org/rustc/command-line-arguments.html#--print-print-compiler-information