Merge pull request #1816 from xlsynth:cdleary/2024-12-30-use-feature-…

…flag PiperOrigin-RevId: 710801795
google · Dec 30, 2024 · 47bdc59 · 47bdc59
2 parents 4651f2e + c61964a
commit 47bdc59
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Showing 6 changed files with 55 additions and 9 deletions.
diff --git a/xls/dslx/fmt/ast_fmt.cc b/xls/dslx/fmt/ast_fmt.cc
@@ -2897,6 +2897,10 @@ absl::StatusOr<DocRef> Formatter::Format(const Module& n) {
           pieces.push_back(arena_.MakeText("#![type_inference_version = 2]"));
           pieces.push_back(arena_.hard_line());
           break;
+        case ModuleAnnotation::kAllowUseSyntax:
+          pieces.push_back(arena_.MakeText("#![feature(use_syntax)]"));
+          pieces.push_back(arena_.hard_line());
+          break;
       }
     }
     pieces.push_back(arena_.hard_line());

diff --git a/xls/dslx/frontend/ast_cloner_test.cc b/xls/dslx/frontend/ast_cloner_test.cc
@@ -1738,7 +1738,9 @@ fn divmod() {})*";
 
 TEST(AstClonerTest, Use) {
   constexpr std::string_view kProgram =
-      R"(use foo::bar::{baz::{bat, qux}, ipsum};)";
+      R"(#![feature(use_syntax)]
+
+use foo::bar::{baz::{bat, qux}, ipsum};)";
 
   FileTable file_table;
   XLS_ASSERT_OK_AND_ASSIGN(auto module, ParseModule(kProgram, "fake_path.x",

diff --git a/xls/dslx/frontend/module.cc b/xls/dslx/frontend/module.cc
@@ -85,6 +85,9 @@ std::string Module::ToString() const {
             case ModuleAnnotation::kTypeInferenceVersion2:
               absl::StrAppend(out, "#![type_inference_version = 2]");
               break;
+            case ModuleAnnotation::kAllowUseSyntax:
+              absl::StrAppend(out, "#![feature(use_syntax)]");
+              break;
           }
         });
     return absl::StrCat(header, "\n\n", body);

diff --git a/xls/dslx/frontend/module.h b/xls/dslx/frontend/module.h
@@ -69,6 +69,9 @@ enum class ModuleAnnotation : uint8_t {
   kAllowNonstandardMemberNaming,
 
   kTypeInferenceVersion2,
+
+  // Enable "use" syntax instead of "import" for this module.
+  kAllowUseSyntax,
 };
 
 // Represents a syntactic module in the AST.

diff --git a/xls/dslx/frontend/parser.cc b/xls/dslx/frontend/parser.cc
@@ -257,6 +257,16 @@ absl::Status Parser::ParseModuleAttribute() {
   Span identifier_span;
   XLS_ASSIGN_OR_RETURN(std::string identifier,
                        PopIdentifierOrError(&identifier_span));
+  if (identifier == "feature") {
+    XLS_RETURN_IF_ERROR(DropTokenOrError(TokenKind::kOParen));
+    XLS_ASSIGN_OR_RETURN(std::string feature, PopIdentifierOrError());
+    if (feature == "use_syntax") {
+      module_->AddAnnotation(ModuleAnnotation::kAllowUseSyntax);
+    }
+    XLS_RETURN_IF_ERROR(DropTokenOrError(TokenKind::kCParen));
+    XLS_RETURN_IF_ERROR(DropTokenOrError(TokenKind::kCBrack));
+    return absl::OkStatus();
+  }
   if (identifier == "type_inference_version") {
     XLS_RETURN_IF_ERROR(DropTokenOrError(TokenKind::kEquals));
     XLS_RETURN_IF_ERROR(ParseTypeInferenceVersionAttribute());
@@ -474,11 +484,25 @@ absl::StatusOr<std::unique_ptr<Module>> Parser::ParseModule(
         break;
       }
       case Keyword::kImport: {
+        if (module_->annotations().contains(
+                ModuleAnnotation::kAllowUseSyntax)) {
+          return ParseErrorStatus(
+              peek->span(),
+              "`import` syntax is disabled for this module via "
+              "`#![feature(use_syntax)]` at module scope; use `use` instead");
+        }
         XLS_ASSIGN_OR_RETURN(Import * import, ParseImport(*bindings));
         XLS_RETURN_IF_ERROR(module_->AddTop(import, make_collision_error));
         break;
       }
       case Keyword::kUse: {
+        if (!module_->annotations().contains(
+                ModuleAnnotation::kAllowUseSyntax)) {
+          return ParseErrorStatus(
+              peek->span(),
+              "`use` syntax is not enabled for this module; enable with "
+              "`#![feature(use_syntax)]` at module scope");
+        }
         XLS_ASSIGN_OR_RETURN(Use * use, ParseUse(*bindings));
         XLS_RETURN_IF_ERROR(module_->AddTop(use, make_collision_error));
         break;

diff --git a/xls/dslx/frontend/parser_test.cc b/xls/dslx/frontend/parser_test.cc
@@ -1666,38 +1666,48 @@ fn foo() -> bar::T<2>[3] {
 }
 
 TEST_F(ParserTest, UseOneItemFromModule) {
-  RoundTrip(R"(use foo::BAR;
+  RoundTrip(R"(#![feature(use_syntax)]
+
+use foo::BAR;
 fn main() -> u32 {
     BAR
 })");
 }
 
 TEST_F(ParserTest, UseTwoItemsFromModule) {
-  RoundTrip(R"(use foo::{BAR, BAZ};
+  RoundTrip(R"(#![feature(use_syntax)]
+
+use foo::{BAR, BAZ};
 fn main() -> u32 {
     BAR + BAZ
 })");
 }
 
 TEST_F(ParserTest, UseWithNestedLevels) {
-  RoundTrip(R"(use foo::{bar::{baz, qux}, quux};
+  RoundTrip(R"(#![feature(use_syntax)]
+
+use foo::{bar::{baz, qux}, quux};
 fn main() -> u32 {
     baz + qux + quux
 })");
 }
 
 TEST_F(ParserTest, UseCollidesWithImport) {
-  constexpr std::string_view kProgram = "use foo; import foo;";
+  constexpr std::string_view kProgram = R"(#![feature(use_syntax)]
+
+use foo; import foo;
+)";
   absl::StatusOr<std::unique_ptr<Module>> module = Parse(kProgram);
   EXPECT_THAT(
       module.status(),
-      StatusIs(
-          absl::StatusCode::kInvalidArgument,
-          HasSubstr("Import of `foo` is shadowing an existing definition")));
+      StatusIs(absl::StatusCode::kInvalidArgument,
+               HasSubstr("`import` syntax is disabled for this module via "
+                         "`#![feature(use_syntax)]` at module scope")));
 }
 
 TEST_F(ParserTest, UseWithPeersAtTopLevelNotAllowed) {
-  constexpr std::string_view kProgram = "use {foo, bar};";
+  constexpr std::string_view kProgram = R"(#![feature(use_syntax)]
+use {foo, bar};)";
   absl::StatusOr<std::unique_ptr<Module>> module = Parse(kProgram);
   EXPECT_THAT(
       module.status(),