rust: track inline module scopes for module file resolution

The set of inline modules is required to find the expected location of a
module file. Track this information with an RAII object
(`InlineModuleStackScope`) and pass it down to any out-of-line modules
so that, when requested, the set of inline modules can be added to the
search path.

Signed-off-by: Ben Boeckel <[email protected]>

Author: mathstuf

gcc/rust/ast/rust-ast-full-test.cc

@@ -4069,13 +4069,21 @@ Module::process_file_path ()
   // the concept of `DirOwnernship`, which is based on whether or not the
   // current file is titled `mod.rs`.
 
+  // Handle inline module declarations adding path components.
+  for (auto const &name : module_scope)
+    {
+      current_directory_name.append (name);
+      current_directory_name.append (file_separator);
+    }
+
   // First, we search for <directory>/<module_name>.rs
-  bool file_mod_found
-    = file_exists (current_directory_name + expected_file_path);
+  std::string file_mod_path = current_directory_name + expected_file_path;
+  bool file_mod_found = file_exists (file_mod_path);
 
   // Then, search for <directory>/<module_name>/mod.rs
-  current_directory_name += module_name + file_separator;
-  bool dir_mod_found = file_exists (current_directory_name + expected_dir_path);
+  std::string dir_mod_path
+    = current_directory_name + module_name + file_separator + expected_dir_path;
+  bool dir_mod_found = file_exists (dir_mod_path);
 
   bool multiple_candidates_found = file_mod_found && dir_mod_found;
   bool no_candidates_found = !file_mod_found && !dir_mod_found;
@@ -4093,8 +4101,7 @@ Module::process_file_path ()
   if (no_candidates_found || multiple_candidates_found)
     return;
 
-  module_file = file_mod_found ? expected_file_path
-			       : current_directory_name + expected_dir_path;
+  module_file = std::move (file_mod_found ? file_mod_path : dir_mod_path);
 }
 
 void

gcc/rust/ast/rust-item.h

@@ -991,6 +991,8 @@ class Module : public VisItem
   std::vector<Attribute> inner_attrs;
   // bool has_items;
   std::vector<std::unique_ptr<Item>> items;
+  // Names of including inline modules (immediate parent is last in the list)
+  std::vector<std::string> module_scope;
 
   // Filename the module refers to. Empty string on LOADED modules or if an
   // error occured when dealing with UNLOADED modules
@@ -1013,11 +1015,12 @@ class Module : public VisItem
   // Unloaded module constructor
   Module (Identifier module_name, Visibility visibility,
 	  std::vector<Attribute> outer_attrs, Location locus,
-	  std::string outer_filename)
+	  std::string outer_filename, std::vector<std::string> module_scope)
     : VisItem (std::move (visibility), std::move (outer_attrs)),
       module_name (module_name), locus (locus), kind (ModuleKind::UNLOADED),
       outer_filename (outer_filename), inner_attrs (std::vector<Attribute> ()),
-      items (std::vector<std::unique_ptr<Item>> ())
+      items (std::vector<std::unique_ptr<Item>> ()),
+      module_scope (std::move (module_scope))
   {}
 
   // Loaded module constructor, with items
@@ -1035,7 +1038,8 @@ class Module : public VisItem
   // Copy constructor with vector clone
   Module (Module const &other)
     : VisItem (other), module_name (other.module_name), locus (other.locus),
-      kind (other.kind), inner_attrs (other.inner_attrs)
+      kind (other.kind), inner_attrs (other.inner_attrs),
+      module_scope (other.module_scope)
   {
     // We need to check whether we are copying a loaded module or an unloaded
     // one. In the second case, clear the `items` vector.
@@ -1054,6 +1058,7 @@ class Module : public VisItem
     locus = other.locus;
     kind = other.kind;
     inner_attrs = other.inner_attrs;
+    module_scope = other.module_scope;
 
     // Likewise, we need to clear the `items` vector in case the other module is
     // unloaded

gcc/rust/parse/rust-parse-impl.h

@@ -2104,11 +2104,13 @@ Parser<ManagedTokenSource>::parse_module (AST::Visibility vis,
       // Construct an external module
       return std::unique_ptr<AST::Module> (
 	new AST::Module (std::move (name), std::move (vis),
-			 std::move (outer_attrs), locus,
-			 lexer.get_filename ()));
+			 std::move (outer_attrs), locus, lexer.get_filename (),
+			 inline_module_stack));
       case LEFT_CURLY: {
 	lexer.skip_token ();
 
+	InlineModuleStackScope scope (*this, name);
+
 	// parse inner attributes
 	AST::AttrVec inner_attrs = parse_inner_attributes ();
 

gcc/rust/parse/rust-parse.h

@@ -622,6 +622,21 @@ template <typename ManagedTokenSource> class Parser
   ManagedTokenSource lexer;
   // The error list.
   std::vector<Error> error_table;
+  // The names of inline modules while parsing.
+  std::vector<std::string> inline_module_stack;
+
+  class InlineModuleStackScope
+  {
+  private:
+    Parser &parser;
+
+  public:
+    InlineModuleStackScope (Parser &parser, std::string name) : parser (parser)
+    {
+      parser.inline_module_stack.emplace_back (std::move (name));
+    }
+    ~InlineModuleStackScope () { parser.inline_module_stack.pop_back (); }
+  };
 };
 } // namespace Rust
 

gcc/testsuite/rust/compile/missing_middle/explicit.not.rs

@@ -0,0 +1 @@
+mod other;

gcc/testsuite/rust/compile/missing_middle/other.rs

@@ -0,0 +1,3 @@
+pub fn f() -> u32 {
+    2
+}

gcc/testsuite/rust/compile/missing_middle/sub/mod.rs

@@ -0,0 +1,3 @@
+pub fn f() -> u32 {
+    1
+}

gcc/testsuite/rust/compile/mod_missing_middle.rs

@@ -0,0 +1,10 @@
+// { dg-additional-options "-w" }
+
+mod missing_middle {
+    mod sub;
+}
+
+mod with_explicit_path {
+    #[path = "missing_middle/explicit.not.rs"]
+    mod explicit;
+}