add rewrite_struct proc-macro and test case

Author: J-ZhengLi

tests/ui/auxiliary/proc_macro_attr.rs

@@ -12,7 +12,7 @@ use syn::spanned::Spanned;
 use syn::token::Star;
 use syn::{
     parse_macro_input, parse_quote, FnArg, ImplItem, ItemFn, ItemImpl, ItemTrait, Lifetime, Pat, PatIdent, PatType,
-    Signature, TraitItem, Type,
+    Signature, TraitItem, Type, ItemStruct, Visibility,
 };
 
 #[proc_macro_attribute]
@@ -101,9 +101,7 @@ pub fn fake_main(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let mut item = parse_macro_input!(item as ItemFn);
     let span = item.block.brace_token.span;
 
-    if item.sig.asyncness.is_some() {
-        item.sig.asyncness = None;
-    }
+    item.sig.asyncness = None;
 
     let crate_name = quote! { fake_crate };
     let block = item.block;
@@ -128,7 +126,7 @@ pub fn fake_main(_attr: TokenStream, item: TokenStream) -> TokenStream {
 
 #[proc_macro_attribute]
 pub fn fake_desugar_await(_args: TokenStream, input: TokenStream) -> TokenStream {
-    let mut async_fn = syn::parse_macro_input!(input as syn::ItemFn);
+    let mut async_fn = parse_macro_input!(input as syn::ItemFn);
 
     for stmt in &mut async_fn.block.stmts {
         if let syn::Stmt::Expr(syn::Expr::Match(syn::ExprMatch { expr: scrutinee, .. }), _) = stmt {
@@ -145,3 +143,23 @@ pub fn fake_desugar_await(_args: TokenStream, input: TokenStream) -> TokenStream
 
     quote!(#async_fn).into()
 }
+
+#[proc_macro_attribute]
+pub fn rewrite_struct(_args: TokenStream, input: TokenStream) -> TokenStream {
+    let mut item_struct = parse_macro_input!(input as syn::ItemStruct);
+    // remove struct attributes including doc comments.
+    item_struct.attrs = vec![];
+    if let Visibility::Public(token) = item_struct.vis {
+        // set vis to `pub(crate)` to trigger `missing_docs_in_private_items` lint.
+        let new_vis: Visibility = syn::parse_quote_spanned!(token.span() => pub(crate));
+        item_struct.vis = new_vis;
+    }
+    if let syn::Fields::Named(fields) = &mut item_struct.fields {
+        for field in &mut fields.named {
+            // remove all attributes from fields as well.
+            field.attrs = vec![];
+        }
+    }
+
+    quote!(#item_struct).into()
+}

tests/ui/missing_doc.rs

@@ -1,5 +1,6 @@
 //@needs-asm-support
 //@aux-build: proc_macros.rs
+//@aux-build: proc_macro_attr.rs
 
 #![warn(clippy::missing_docs_in_private_items)]
 // When denying at the crate level, be sure to not get random warnings from the
@@ -8,6 +9,8 @@
 //! Some garbage docs for the crate here
 #![doc = "More garbage"]
 
+#[macro_use]
+extern crate proc_macro_attr;
 extern crate proc_macros;
 
 use proc_macros::with_span;
@@ -112,3 +115,12 @@ with_span!(span pub enum FooPm3 { A, B(u32), C { field: u32 }});
 with_span!(span pub fn foo_pm() {});
 with_span!(span pub static FOO_PM: u32 = 0;);
 with_span!(span pub const FOO2_PM: u32 = 0;);
+
+// issue #12197
+// Undocumented field originated inside of spanned proc-macro attribute
+/// Some dox for struct.
+#[rewrite_struct]
+pub struct Test {
+    /// Dox
+    a: u8,
+}

tests/ui/missing_doc.stderr

@@ -1,5 +1,5 @@
 error: missing documentation for a type alias
-  --> tests/ui/missing_doc.rs:16:1
+  --> tests/ui/missing_doc.rs:19:1
    |
 LL | type Typedef = String;
    | ^^^^^^^^^^^^^^^^^^^^^^
@@ -8,19 +8,19 @@ LL | type Typedef = String;
    = help: to override `-D warnings` add `#[allow(clippy::missing_docs_in_private_items)]`
 
 error: missing documentation for a module
-  --> tests/ui/missing_doc.rs:19:1
+  --> tests/ui/missing_doc.rs:22:1
    |
 LL | mod module_no_dox {}
    | ^^^^^^^^^^^^^^^^^^^^
 
 error: missing documentation for a function
-  --> tests/ui/missing_doc.rs:25:1
+  --> tests/ui/missing_doc.rs:28:1
    |
 LL | fn foo3() {}
    | ^^^^^^^^^^^^
 
 error: missing documentation for an enum
-  --> tests/ui/missing_doc.rs:39:1
+  --> tests/ui/missing_doc.rs:42:1
    |
 LL | / enum Baz {
 LL | |     BazA { a: isize, b: isize },
@@ -29,43 +29,43 @@ LL | | }
    | |_^
 
 error: missing documentation for a variant
-  --> tests/ui/missing_doc.rs:40:5
+  --> tests/ui/missing_doc.rs:43:5
    |
 LL |     BazA { a: isize, b: isize },
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: missing documentation for a struct field
-  --> tests/ui/missing_doc.rs:40:12
+  --> tests/ui/missing_doc.rs:43:12
    |
 LL |     BazA { a: isize, b: isize },
    |            ^^^^^^^^
 
 error: missing documentation for a struct field
-  --> tests/ui/missing_doc.rs:40:22
+  --> tests/ui/missing_doc.rs:43:22
    |
 LL |     BazA { a: isize, b: isize },
    |                      ^^^^^^^^
 
 error: missing documentation for a variant
-  --> tests/ui/missing_doc.rs:41:5
+  --> tests/ui/missing_doc.rs:44:5
    |
 LL |     BarB,
    |     ^^^^
 
 error: missing documentation for a constant
-  --> tests/ui/missing_doc.rs:65:1
+  --> tests/ui/missing_doc.rs:68:1
    |
 LL | const FOO: u32 = 0;
    | ^^^^^^^^^^^^^^^^^^^
 
 error: missing documentation for a static
-  --> tests/ui/missing_doc.rs:74:1
+  --> tests/ui/missing_doc.rs:77:1
    |
 LL | static BAR: u32 = 0;
    | ^^^^^^^^^^^^^^^^^^^^
 
 error: missing documentation for a module
-  --> tests/ui/missing_doc.rs:83:1
+  --> tests/ui/missing_doc.rs:86:1
    |
 LL | / mod internal_impl {
 LL | |     /// dox
@@ -77,16 +77,31 @@ LL | | }
    | |_^
 
 error: missing documentation for a function
-  --> tests/ui/missing_doc.rs:88:5
+  --> tests/ui/missing_doc.rs:91:5
    |
 LL |     fn undocumented3() {}
    |     ^^^^^^^^^^^^^^^^^^^^^
 
 error: missing documentation for a function
-  --> tests/ui/missing_doc.rs:94:9
+  --> tests/ui/missing_doc.rs:97:9
    |
 LL |         fn also_undocumented2() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 13 previous errors
+error: missing documentation for a struct
+  --> tests/ui/missing_doc.rs:123:1
+   |
+LL | / pub struct Test {
+LL | |     /// Dox
+LL | |     a: u8,
+LL | | }
+   | |_^
+
+error: missing documentation for a struct field
+  --> tests/ui/missing_doc.rs:125:5
+   |
+LL |     a: u8,
+   |     ^^^^^
+
+error: aborting due to 15 previous errors