4 files changed, 73 insertions, 0 deletions

diff --git a/gcc/rust/expand/rust-macro-builtins.cc b/gcc/rust/expand/rust-macro-builtins.cc
index 8c68a7d..fb30241 100644
--- a/gcc/rust/expand/rust-macro-builtins.cc
+++ b/gcc/rust/expand/rust-macro-builtins.cc
@@ -412,4 +412,60 @@ MacroBuiltin::cfg (Location invoc_locus, AST::MacroInvocData &invoc)
   return AST::ASTFragment ({literal_exp});
 }
 
+/* Expand builtin macro include!(), which includes a source file at the current
+ scope compile time. */
+
+AST::ASTFragment
+MacroBuiltin::include (Location invoc_locus, AST::MacroInvocData &invoc)
+{
+  /* Get target filename from the macro invocation, which is treated as a path
+     relative to the include!-ing file (currently being compiled).  */
+  auto lit_expr
+    = parse_single_string_literal (invoc.get_delim_tok_tree (), invoc_locus);
+  if (lit_expr == nullptr)
+    return AST::ASTFragment::create_error ();
+
+  std::string filename
+    = source_relative_path (lit_expr->as_string (), invoc_locus);
+  auto target_filename
+    = Rust::Session::get_instance ().include_extra_file (std::move (filename));
+
+  RAIIFile target_file (target_filename);
+  Linemap *linemap = Session::get_instance ().linemap;
+
+  if (target_file.get_raw () == nullptr)
+    {
+      rust_error_at (lit_expr->get_locus (),
+		     "cannot open included file %qs: %m", target_filename);
+      return AST::ASTFragment::create_error ();
+    }
+
+  rust_debug ("Attempting to parse included file %s", target_filename);
+
+  Lexer lex (target_filename, std::move (target_file), linemap);
+  Parser<Lexer> parser (std::move (lex));
+
+  auto parsed_items = parser.parse_items ();
+  bool has_error = !parser.get_errors ().empty ();
+
+  for (const auto &error : parser.get_errors ())
+    error.emit_error ();
+
+  if (has_error)
+    {
+      // inform the user that the errors above are from a included file
+      rust_inform (invoc_locus, "included from here");
+      return AST::ASTFragment::create_error ();
+    }
+
+  std::vector<AST::SingleASTNode> nodes{};
+  for (auto &item : parsed_items)
+    {
+      AST::SingleASTNode node (std::move (item));
+      nodes.push_back (node);
+    }
+
+  return AST::ASTFragment (nodes);
+}
+
 } // namespace Rust
diff --git a/gcc/rust/expand/rust-macro-builtins.h b/gcc/rust/expand/rust-macro-builtins.h
index e284c03..f1d10df 100644
--- a/gcc/rust/expand/rust-macro-builtins.h
+++ b/gcc/rust/expand/rust-macro-builtins.h
@@ -95,6 +95,9 @@ public:
 
   static AST::ASTFragment cfg (Location invoc_locus,
 			       AST::MacroInvocData &invoc);
+
+  static AST::ASTFragment include (Location invoc_locus,
+				   AST::MacroInvocData &invoc);
 };
 } // namespace Rust
 
diff --git a/gcc/rust/rust-session-manager.h b/gcc/rust/rust-session-manager.h
index 6fa83d9..0c15711 100644
--- a/gcc/rust/rust-session-manager.h
+++ b/gcc/rust/rust-session-manager.h
@@ -235,6 +235,10 @@ struct Session
    * every file so eh. */
   std::string injected_crate_name;
 
+  /* extra files get included during late stages of compilation (e.g. macro
+   * expansion) */
+  std::vector<std::string> extra_files;
+
   // backend wrapper to GCC GENERIC
   Backend *backend;
 
@@ -267,6 +271,15 @@ public:
   void parse_files (int num_files, const char **files);
   void init_options ();
 
+  /* This function saves the filename data into the session manager using the
+   * `move` semantics, and returns a C-style string referencing the input
+   * std::string */
+  inline const char *include_extra_file (std::string filename)
+  {
+    extra_files.push_back (std::move (filename));
+    return extra_files.back ().c_str ();
+  }
+
 private:
   Session () = default;
   void parse_file (const char *filename);
diff --git a/gcc/rust/util/rust-hir-map.cc b/gcc/rust/util/rust-hir-map.cc
index e9ad87c..b08258c 100644
--- a/gcc/rust/util/rust-hir-map.cc
+++ b/gcc/rust/util/rust-hir-map.cc
@@ -757,6 +757,7 @@ Mappings::insert_macro_def (AST::MacroRulesDefinition *macro)
       {"concat", MacroBuiltin::concat},
       {"env", MacroBuiltin::env},
       {"cfg", MacroBuiltin::cfg},
+      {"include", MacroBuiltin::include},
     };
 
   auto builtin = builtin_macros.find (macro->get_rule_name ());