misc fixes

pdl-compiler/src/analyzer.rs

@@ -535,13 +535,17 @@ fn scalar_max(width: usize) -> usize {
 ///      - undeclared test identifier
 ///      - invalid test identifier
 ///      - recursive declaration
-fn check_decl_identifiers(file: &File, scope: &Scope) -> Result<(), Diagnostics> {
+///
+/// Returns a copy of the file where the declarations have been
+/// reordered by topological sort to remove forward references.
+fn check_decl_identifiers(file: &File, scope: &Scope) -> Result<File, Diagnostics> {
     enum Mark {
         Temporary,
         Permanent,
     }
     #[derive(Default)]
     struct Context<'d> {
+        history: Vec<Decl>,
         visited: HashMap<&'d str, Mark>,
     }
 
@@ -669,6 +673,7 @@ fn check_decl_identifiers(file: &File, scope: &Scope) -> Result<(), Diagnostics>
         }
 
         // Done visiting current declaration.
+        context.history.push(decl.clone());
         context.visited.insert(decl_id, Mark::Permanent);
     }
 
@@ -677,10 +682,12 @@ fn check_decl_identifiers(file: &File, scope: &Scope) -> Result<(), Diagnostics>
     let mut context = Default::default();
     for decl in &file.declarations {
         match &decl.desc {
-            DeclDesc::Checksum { .. } | DeclDesc::CustomField { .. } | DeclDesc::Enum { .. } => (),
-            DeclDesc::Packet { .. } | DeclDesc::Struct { .. } | DeclDesc::Group { .. } => {
-                bfs(decl, &mut context, scope, &mut diagnostics)
-            }
+            DeclDesc::Checksum { .. }
+            | DeclDesc::CustomField { .. }
+            | DeclDesc::Enum { .. }
+            | DeclDesc::Packet { .. }
+            | DeclDesc::Struct { .. }
+            | DeclDesc::Group { .. } => bfs(decl, &mut context, scope, &mut diagnostics),
             DeclDesc::Test { type_id, .. } => match scope.typedef.get(type_id) {
                 None => diagnostics.push(
                     Diagnostic::error()
@@ -701,7 +708,14 @@ fn check_decl_identifiers(file: &File, scope: &Scope) -> Result<(), Diagnostics>
         }
     }
 
-    diagnostics.err_or(())
+    diagnostics.err_or(File {
+        version: file.version.clone(),
+        file: file.file,
+        comments: file.comments.clone(),
+        endianness: file.endianness,
+        declarations: context.history,
+        max_key: file.max_key,
+    })
 }
 
 /// Check field identifiers.
@@ -1845,18 +1859,19 @@ fn desugar_flags(file: &mut File) {
 /// from the analysis.
 pub fn analyze(file: &File) -> Result<File, Diagnostics> {
     let scope = Scope::new(file)?;
-    check_decl_identifiers(file, &scope)?;
-    check_field_identifiers(file)?;
-    check_enum_declarations(file)?;
-    check_size_fields(file)?;
-    check_fixed_fields(file, &scope)?;
-    check_payload_fields(file)?;
-    check_array_fields(file)?;
-    check_padding_fields(file)?;
-    check_checksum_fields(file, &scope)?;
-    check_optional_fields(file)?;
-    check_group_constraints(file, &scope)?;
-    let mut file = inline_groups(file)?;
+    let file = check_decl_identifiers(file, &scope)?;
+    let scope = Scope::new(&file).unwrap();
+    check_field_identifiers(&file)?;
+    check_enum_declarations(&file)?;
+    check_size_fields(&file)?;
+    check_fixed_fields(&file, &scope)?;
+    check_payload_fields(&file)?;
+    check_array_fields(&file)?;
+    check_padding_fields(&file)?;
+    check_checksum_fields(&file, &scope)?;
+    check_optional_fields(&file)?;
+    check_group_constraints(&file, &scope)?;
+    let mut file = inline_groups(&file)?;
     desugar_flags(&mut file);
     let scope = Scope::new(&file)?;
     check_decl_constraints(&file, &scope)?;
@@ -3218,6 +3233,76 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_decl_ordering() {
+        valid!(
+            r#"
+        little_endian_packets
+        packet A {
+            b: B,
+        }
+
+        enum B : 8 {
+            X = 0,
+            Y = 1,
+            Z = 127,
+        }
+        "#
+        );
+
+        valid!(
+            r#"
+        little_endian_packets
+        packet A {
+            b: B,
+        }
+
+        struct B {
+            a: 7,
+            b: 9,
+        }
+        "#
+        );
+
+        valid!(
+            r#"
+        little_endian_packets
+        packet A {
+            f: F,
+        }
+
+        custom_field F : 8 "f"
+        "#
+        );
+
+        valid!(
+            r#"
+        little_endian_packets
+        packet A {
+            G,
+        }
+
+        group G {
+            a: 8,
+        }
+        "#
+        );
+
+        valid!(
+            r#"
+        little_endian_packets
+        packet A : B {
+            b: 16,
+        }
+
+        packet B {
+            a: 8,
+            _payload_
+        }
+        "#
+        );
+    }
+
     #[test]
     fn test_enum_declaration() {
         valid!(

pdl-compiler/src/main.rs

@@ -66,8 +66,8 @@ struct Opt {
     test_file: Option<String>,
 
     #[argh(positional)]
-    /// input file.
-    input_file: String,
+    /// input files.
+    input_file: Option<String>,
 
     #[argh(option)]
     /// exclude declarations from the generated output.
@@ -104,9 +104,9 @@ fn filter_declarations(file: ast::File, exclude_declarations: &[String]) -> ast:
     }
 }
 
-fn generate_backend(opt: &Opt) -> Result<(), String> {
+fn generate_backend(opt: &Opt, input_file: &str) -> Result<(), String> {
     let mut sources = ast::SourceDatabase::new();
-    match parser::parse_file(&mut sources, &opt.input_file) {
+    match parser::parse_file(&mut sources, input_file) {
         Ok(file) => {
             let file = filter_declarations(file, &opt.exclude_declaration);
             let analyzed_file = match analyzer::analyze(&file) {
@@ -174,7 +174,7 @@ fn generate_backend(opt: &Opt) -> Result<(), String> {
     }
 }
 
-fn generate_tests(opt: &Opt, test_file: &str) -> Result<(), String> {
+fn generate_tests(opt: &Opt, test_file: &str, _input_file: &str) -> Result<(), String> {
     match opt.output_format {
         OutputFormat::Rust => {
             println!("{}", backends::rust::test::generate_tests(test_file)?);
@@ -199,7 +199,7 @@ fn generate_tests(opt: &Opt, test_file: &str) -> Result<(), String> {
                 test_file,
                 std::path::Path::new(output_dir),
                 package.clone(),
-                &opt.input_file,
+                _input_file,
                 &opt.exclude_declaration,
             )
         }
@@ -214,13 +214,19 @@ fn main() -> Result<(), String> {
     let opt: Opt = argh::from_env();
 
     if opt.version {
-        println!("Packet Description Language parser version 1.0");
+        println!("pdlc {}\nCopyright (C) 2026 Google LLC", env!("CARGO_PKG_VERSION"));
         return Ok(());
     }
 
+    let Some(input_file) = opt.input_file.as_ref() else {
+        return Err("No input file is specified".to_owned());
+    };
+
     if let Some(test_file) = opt.test_file.as_ref() {
-        generate_tests(&opt, test_file)
+        generate_tests(&opt, test_file, input_file)?
     } else {
-        generate_backend(&opt)
+        generate_backend(&opt, input_file)?
     }
+
+    Ok(())
 }