fix(es/resolver): Fix handling of decorators (#4084)

crates/swc_ecma_codegen/src/typescript.rs

@@ -638,6 +638,10 @@ where
 
         self.emit_accessibility(n.accessibility)?;
 
+        for dec in &n.decorators {
+            emit!(dec);
+        }
+
         if n.is_override {
             keyword!("override");
             space!();

crates/swc_ecma_transforms_base/src/resolver/mod.rs

@@ -565,6 +565,8 @@ impl<'a> VisitMut for Resolver<'a> {
     fn visit_mut_class_decl(&mut self, n: &mut ClassDecl) {
         self.modify(&mut n.ident, None);
 
+        n.class.decorators.visit_mut_with(self);
+
         // Create a child scope. The class name is only accessible within the class.
         let child_mark = Mark::fresh(Mark::root());
 
@@ -597,6 +599,10 @@ impl<'a> VisitMut for Resolver<'a> {
     fn visit_mut_class_method(&mut self, m: &mut ClassMethod) {
         m.key.visit_mut_with(self);
 
+        for p in m.function.params.iter_mut() {
+            p.decorators.visit_mut_with(self);
+        }
+
         {
             let child_mark = Mark::fresh(Mark::root());
 
@@ -631,6 +637,17 @@ impl<'a> VisitMut for Resolver<'a> {
     fn visit_mut_constructor(&mut self, c: &mut Constructor) {
         let child_mark = Mark::fresh(Mark::root());
 
+        for p in c.params.iter_mut() {
+            match p {
+                ParamOrTsParamProp::TsParamProp(p) => {
+                    p.decorators.visit_mut_with(self);
+                }
+                ParamOrTsParamProp::Param(p) => {
+                    p.decorators.visit_mut_with(self);
+                }
+            }
+        }
+
         // Child folder
         let mut folder = Resolver::new(
             Scope::new(ScopeKind::Fn, child_mark, Some(&self.current)),
@@ -696,6 +713,8 @@ impl<'a> VisitMut for Resolver<'a> {
     fn visit_mut_fn_decl(&mut self, node: &mut FnDecl) {
         // We don't fold this as Hoister handles this.
 
+        node.function.decorators.visit_mut_with(self);
+
         {
             let child_mark = Mark::fresh(Mark::root());
 
@@ -710,6 +729,8 @@ impl<'a> VisitMut for Resolver<'a> {
     }
 
     fn visit_mut_fn_expr(&mut self, e: &mut FnExpr) {
+        e.function.decorators.visit_mut_with(self);
+
         let child_mark = Mark::fresh(Mark::root());
 
         // Child folder
@@ -789,6 +810,10 @@ impl<'a> VisitMut for Resolver<'a> {
     }
 
     fn visit_mut_ident(&mut self, i: &mut Ident) {
+        if i.span.ctxt != SyntaxContext::empty() {
+            return;
+        }
+
         match self.ident_type {
             IdentType::Binding => self.modify(i, None),
             IdentType::Ref => {

crates/swc_ecma_transforms_base/tests/fixture.rs

@@ -3,7 +3,7 @@ use std::path::{Path, PathBuf};
 use swc_common::{chain, sync::Lrc, Mark, SourceMap, SyntaxContext};
 use swc_ecma_ast::*;
 use swc_ecma_codegen::Emitter;
-use swc_ecma_parser::{lexer::Lexer, EsConfig, Parser, StringInput, Syntax};
+use swc_ecma_parser::{lexer::Lexer, EsConfig, Parser, StringInput, Syntax, TsConfig};
 use swc_ecma_transforms_base::{
     fixer::fixer,
     resolver::{resolver_with_mark, ts_resolver},
@@ -90,15 +90,22 @@ fn test_resolver(input: PathBuf) {
 
 #[fixture("tests/ts-resolver/**/input.ts")]
 fn test_ts_resolver(input: PathBuf) {
-    run(Syntax::Typescript(Default::default()), &input, || {
-        let top_level_mark = Mark::fresh(Mark::root());
+    run(
+        Syntax::Typescript(TsConfig {
+            decorators: true,
+            ..Default::default()
+        }),
+        &input,
+        || {
+            let top_level_mark = Mark::fresh(Mark::root());
 
-        chain!(
-            ts_resolver(top_level_mark),
-            as_folder(TsHygiene { top_level_mark }),
-            fixer(None)
-        )
-    });
+            chain!(
+                ts_resolver(top_level_mark),
+                as_folder(TsHygiene { top_level_mark }),
+                fixer(None)
+            )
+        },
+    );
 }
 
 struct TsHygiene {

crates/swc_ecma_transforms_base/tests/ts-resolver/issues/3960/1/input.ts

@@ -0,0 +1,7 @@
+import { field } from "../validation/decorators";
+class C {
+    constructor(
+        @field("a") readonly field: string,
+        @field("b") readonly b: string,
+    ) { }
+}

crates/swc_ecma_transforms_base/tests/ts-resolver/issues/3960/1/output.ts

@@ -0,0 +1,6 @@
+import { field } from "../validation/decorators";
+class C {
+    constructor(@field("a")
+    readonly field__2: string, @field("b")
+    readonly b__2: string){}
+}

crates/swc_ecma_transforms_base/tests/ts-resolver/issues/3960/2/input.ts

@@ -0,0 +1,7 @@
+import { field } from "../validation/decorators";
+class C {
+    method(
+        @field("a") readonly field: string,
+        @field("b") readonly b: string,
+    ) { }
+}

crates/swc_ecma_transforms_base/tests/ts-resolver/issues/3960/2/output.ts

@@ -0,0 +1,8 @@
+import { field } from "../validation/decorators";
+class C {
+    method(
+    @field("a")
+    field__2: string, 
+    @field("b")
+    b__2: string) {}
+}