Rust: exclude extraction of code excluded by cfg

Author: Paolo Tranquilli

rust/ast-generator/src/main.rs

@@ -4,6 +4,7 @@ use std::{fs, path::PathBuf};
 pub mod codegen;
 mod flags;
 use codegen::grammar::ast_src::{AstNodeSrc, AstSrc, Field};
+use itertools::Itertools;
 use std::collections::{BTreeMap, BTreeSet};
 use std::env;
 use ungrammar::Grammar;
@@ -475,10 +476,10 @@ use ra_ap_syntax::ast::{{
 use ra_ap_syntax::{{ast, AstNode}};
 
 impl Translator<'_> {{
-    fn emit_else_branch(&mut self, node: ast::ElseBranch) -> Label<generated::Expr> {{
+    fn emit_else_branch(&mut self, node: ast::ElseBranch) -> Option<Label<generated::Expr>> {{
         match node {{
-            ast::ElseBranch::IfExpr(inner) => self.emit_if_expr(inner).into(),
-            ast::ElseBranch::Block(inner) => self.emit_block_expr(inner).into(),
+            ast::ElseBranch::IfExpr(inner) => self.emit_if_expr(inner).map(Into::into),
+            ast::ElseBranch::Block(inner) => self.emit_block_expr(inner).map(Into::into),
         }}
     }}\n"
     )?;
@@ -488,7 +489,7 @@ impl Translator<'_> {{
 
         writeln!(
             buf,
-            "    pub(crate) fn emit_{}(&mut self, node: ast::{}) -> Label<generated::{}> {{",
+            "    pub(crate) fn emit_{}(&mut self, node: ast::{}) -> Option<Label<generated::{}>> {{",
             to_lower_snake_case(type_name),
             type_name,
             class_name
@@ -497,7 +498,7 @@ impl Translator<'_> {{
         for variant in &node.variants {
             writeln!(
                 buf,
-                "            ast::{}::{}(inner) => self.emit_{}(inner).into(),",
+                "            ast::{}::{}(inner) => self.emit_{}(inner).map(Into::into),",
                 type_name,
                 variant,
                 to_lower_snake_case(variant)
@@ -513,7 +514,7 @@ impl Translator<'_> {{
 
         writeln!(
             buf,
-            "    pub(crate) fn emit_{}(&mut self, node: ast::{}) -> Label<generated::{}> {{",
+            "    pub(crate) fn emit_{}(&mut self, node: ast::{}) -> Option<Label<generated::{}>> {{",
             to_lower_snake_case(type_name),
             type_name,
             class_name
@@ -523,6 +524,15 @@ impl Translator<'_> {{
                 continue;
             }
 
+            if field.name == "attrs" {
+                // special case: this means the node type implements `HasAttrs`, and we want to
+                // check whether it was not excluded by a `cfg` attribute
+                writeln!(
+                    buf,
+                    "        if self.should_be_excluded(&node) {{ return None; }}"
+                )?;
+            }
+
             let type_name = &field.tp;
             let struct_field_name = &field.name;
             let class_field_name = property_name(&node.name, &field.name);
@@ -542,15 +552,15 @@ impl Translator<'_> {{
             } else if field.is_many {
                 writeln!(
                     buf,
-                    "        let {} = node.{}().map(|x| self.emit_{}(x)).collect();",
+                    "        let {} = node.{}().filter_map(|x| self.emit_{}(x)).collect();",
                     class_field_name,
                     struct_field_name,
                     to_lower_snake_case(type_name)
                 )?;
             } else {
                 writeln!(
                     buf,
-                    "        let {} = node.{}().map(|x| self.emit_{}(x));",
+                    "        let {} = node.{}().and_then(|x| self.emit_{}(x));",
                     class_field_name,
                     struct_field_name,
                     to_lower_snake_case(type_name)
@@ -582,7 +592,7 @@ impl Translator<'_> {{
             buf,
             "        self.emit_tokens(&node, label.into(), node.syntax().children_with_tokens());"
         )?;
-        writeln!(buf, "        label")?;
+        writeln!(buf, "        Some(label)")?;
 
         writeln!(buf, "    }}\n")?;
     }

rust/extractor/src/translate/base.rs

@@ -1,5 +1,4 @@
 use super::mappings::{AddressableAst, AddressableHir, PathAst};
-use crate::generated::MacroCall;
 use crate::generated::{self};
 use crate::rust_analyzer::FileSemanticInformation;
 use crate::trap::{DiagnosticSeverity, TrapFile, TrapId};
@@ -267,22 +266,22 @@ impl<'a> Translator<'a> {
         expanded: SyntaxNode,
     ) -> Option<Label<generated::AstNode>> {
         match expand_to {
-            ra_ap_hir_expand::ExpandTo::Statements => {
-                ast::MacroStmts::cast(expanded).map(|x| self.emit_macro_stmts(x).into())
-            }
-            ra_ap_hir_expand::ExpandTo::Items => {
-                ast::MacroItems::cast(expanded).map(|x| self.emit_macro_items(x).into())
-            }
+            ra_ap_hir_expand::ExpandTo::Statements => ast::MacroStmts::cast(expanded)
+                .and_then(|x| self.emit_macro_stmts(x))
+                .map(Into::into),
+            ra_ap_hir_expand::ExpandTo::Items => ast::MacroItems::cast(expanded)
+                .and_then(|x| self.emit_macro_items(x))
+                .map(Into::into),
 
-            ra_ap_hir_expand::ExpandTo::Pattern => {
-                ast::Pat::cast(expanded).map(|x| self.emit_pat(x).into())
-            }
-            ra_ap_hir_expand::ExpandTo::Type => {
-                ast::Type::cast(expanded).map(|x| self.emit_type(x).into())
-            }
-            ra_ap_hir_expand::ExpandTo::Expr => {
-                ast::Expr::cast(expanded).map(|x| self.emit_expr(x).into())
-            }
+            ra_ap_hir_expand::ExpandTo::Pattern => ast::Pat::cast(expanded)
+                .and_then(|x| self.emit_pat(x))
+                .map(Into::into),
+            ra_ap_hir_expand::ExpandTo::Type => ast::Type::cast(expanded)
+                .and_then(|x| self.emit_type(x))
+                .map(Into::into),
+            ra_ap_hir_expand::ExpandTo::Expr => ast::Expr::cast(expanded)
+                .and_then(|x| self.emit_expr(x))
+                .map(Into::into),
         }
     }
     pub(crate) fn extract_macro_call_expanded(
@@ -295,7 +294,7 @@ impl<'a> Translator<'a> {
             let expand_to = ra_ap_hir_expand::ExpandTo::from_call_site(mcall);
             let kind = expanded.kind();
             if let Some(value) = self.emit_expanded_as(expand_to, expanded) {
-                MacroCall::emit_expanded(label, value, &mut self.trap.writer);
+                generated::MacroCall::emit_expanded(label, value, &mut self.trap.writer);
             } else {
                 let range = self.text_range_for_node(mcall);
                 self.emit_parse_error(mcall, &SyntaxError::new(
@@ -559,4 +558,18 @@ impl<'a> Translator<'a> {
             Some(())
         })();
     }
+
+    pub(crate) fn should_be_excluded(&self, item: &impl ast::HasAttrs) -> bool {
+        let Some(sema) = self.semantics else {
+            return false;
+        };
+        for attr in item.attrs() {
+            if let Some((name, tokens)) = attr.as_simple_call() {
+                if name == "cfg" && sema.check_cfg_attr(&tokens) == Some(false) {
+                    return true;
+                }
+            }
+        }
+        false
+    }
 }