gccrs: Add rest pattern support for AST::SlicePattern

The main change can be found in ast/rust-pattern.h, which introduces 2 item types for
AST::SlicePattern - one without rest pattern (SlicePatternItemsNoRest) & the other with
it (SlicePatternItemsHasRest). This led to a number of cascading changes as seen in the
changelog.

gcc/rust/ChangeLog:

	* ast/rust-ast-collector.cc: Add support for the 2 new classes.
	* ast/rust-ast-collector.h: Header file update for above.
	* ast/rust-ast-full-decls.h: Add forward decls for the 2 new classes.
	* ast/rust-ast-visitor.cc: Add visit support for the 2 new classes.
	* ast/rust-ast-visitor.h: Header file update for above.
	* ast/rust-pattern.cc: Implementation of certain methods for the 2 new classes.
	* ast/rust-pattern.h: Define the 2 new classes. Update SlicePattern to be able to hold
	2 kinds of items - SlicePatternItemsNoRest or SlicePatternItemsRest.
	* expand/rust-cfg-strip.cc: Add support for the 2 new classes.
	* expand/rust-cfg-strip.h: Header file update for above.
	* expand/rust-derive.h: Add visits for the 2 new classes.
	* hir/rust-ast-lower-base.cc: Add visits for the 2 new classes.
	* hir/rust-ast-lower-base.h: Header file update for above.
	* hir/rust-ast-lower-pattern.cc: Update lowering of SlicePattern to support
	SlicePatternItemsNoRest.
	* parse/rust-parse-impl.h (parse_slice_pattern()): Add support for parsing DOT_DOT into
	respective SlicePatternItems.
	* resolve/rust-ast-resolve-base.cc: Add visits for the 2 new classes.
	* resolve/rust-ast-resolve-base.h: Header file update for above.
	* resolve/rust-ast-resolve-pattern.cc: Update SlicePattern resolution to support new
	classes.

Signed-off-by: Yap Zhi Heng <[email protected]>

Author: Polygonalr

gcc/rust/ast/rust-ast-collector.cc

@@ -2717,11 +2717,35 @@ TokenCollector::visit (GroupedPattern &pattern)
   push (Rust::Token::make (RIGHT_PAREN, UNDEF_LOCATION));
 }
 
+void
+TokenCollector::visit (SlicePatternItemsNoRest &items)
+{
+  visit_items_joined_by_separator (items.get_patterns (), COMMA);
+}
+
+void
+TokenCollector::visit (SlicePatternItemsHasRest &items)
+{
+  if (!items.get_lower_patterns ().empty ())
+    {
+      visit_items_joined_by_separator (items.get_lower_patterns (), COMMA);
+      push (Rust::Token::make (COMMA, UNDEF_LOCATION));
+    }
+
+  push (Rust::Token::make (DOT_DOT, UNDEF_LOCATION));
+
+  if (!items.get_upper_patterns ().empty ())
+    {
+      push (Rust::Token::make (COMMA, UNDEF_LOCATION));
+      visit_items_joined_by_separator (items.get_upper_patterns (), COMMA);
+    }
+}
+
 void
 TokenCollector::visit (SlicePattern &pattern)
 {
   push (Rust::Token::make (LEFT_SQUARE, pattern.get_locus ()));
-  visit_items_joined_by_separator (pattern.get_items (), COMMA);
+  visit (pattern.get_items ());
   push (Rust::Token::make (RIGHT_SQUARE, UNDEF_LOCATION));
 }
 

gcc/rust/ast/rust-ast-collector.h

@@ -378,6 +378,8 @@ class TokenCollector : public ASTVisitor
   void visit (TuplePatternItemsRanged &tuple_items);
   void visit (TuplePattern &pattern);
   void visit (GroupedPattern &pattern);
+  void visit (SlicePatternItemsNoRest &items);
+  void visit (SlicePatternItemsHasRest &items);
   void visit (SlicePattern &pattern);
   void visit (AltPattern &pattern);
 

gcc/rust/ast/rust-ast-full-decls.h

@@ -248,6 +248,8 @@ class TuplePatternItemsMultiple;
 class TuplePatternItemsRanged;
 class TuplePattern;
 class GroupedPattern;
+class SlicePatternItemsNoRest;
+class SlicePatternItemsHasRest;
 class SlicePattern;
 class AltPattern;
 

gcc/rust/ast/rust-ast-visitor.cc

@@ -1347,12 +1347,27 @@ DefaultASTVisitor::visit (AST::GroupedPattern &pattern)
 }
 
 void
-DefaultASTVisitor::visit (AST::SlicePattern &pattern)
+DefaultASTVisitor::visit (AST::SlicePatternItemsNoRest &items)
 {
-  for (auto &item : pattern.get_items ())
+  for (auto &item : items.get_patterns ())
+    visit (item);
+}
+
+void
+DefaultASTVisitor::visit (AST::SlicePatternItemsHasRest &items)
+{
+  for (auto &item : items.get_lower_patterns ())
+    visit (item);
+  for (auto &item : items.get_upper_patterns ())
     visit (item);
 }
 
+void
+DefaultASTVisitor::visit (AST::SlicePattern &pattern)
+{
+  visit (pattern.get_items ());
+}
+
 void
 DefaultASTVisitor::visit (AST::AltPattern &pattern)
 {

gcc/rust/ast/rust-ast-visitor.h

@@ -212,6 +212,8 @@ class ASTVisitor
   virtual void visit (TuplePatternItemsRanged &tuple_items) = 0;
   virtual void visit (TuplePattern &pattern) = 0;
   virtual void visit (GroupedPattern &pattern) = 0;
+  virtual void visit (SlicePatternItemsNoRest &items) = 0;
+  virtual void visit (SlicePatternItemsHasRest &items) = 0;
   virtual void visit (SlicePattern &pattern) = 0;
   virtual void visit (AltPattern &pattern) = 0;
 
@@ -386,6 +388,8 @@ class DefaultASTVisitor : public ASTVisitor
   virtual void visit (AST::TuplePatternItemsRanged &tuple_items) override;
   virtual void visit (AST::TuplePattern &pattern) override;
   virtual void visit (AST::GroupedPattern &pattern) override;
+  virtual void visit (AST::SlicePatternItemsNoRest &items) override;
+  virtual void visit (AST::SlicePatternItemsHasRest &items) override;
   virtual void visit (AST::SlicePattern &pattern) override;
   virtual void visit (AST::AltPattern &pattern) override;
   virtual void visit (AST::EmptyStmt &stmt) override;

gcc/rust/ast/rust-pattern.cc

@@ -327,16 +327,52 @@ GroupedExpr::as_string () const
 }
 
 std::string
-SlicePattern::as_string () const
+SlicePatternItemsNoRest::as_string () const
 {
-  std::string str ("SlicePattern: ");
+  std::string str;
 
-  for (const auto &pattern : items)
+  for (const auto &pattern : patterns)
     str += "\n " + pattern->as_string ();
 
   return str;
 }
 
+std::string
+SlicePatternItemsHasRest::as_string () const
+{
+  std::string str;
+
+  str += "\n Lower patterns: ";
+  if (lower_patterns.empty ())
+    {
+      str += "none";
+    }
+  else
+    {
+      for (const auto &lower : lower_patterns)
+	str += "\n  " + lower->as_string ();
+    }
+
+  str += "\n Upper patterns: ";
+  if (upper_patterns.empty ())
+    {
+      str += "none";
+    }
+  else
+    {
+      for (const auto &upper : upper_patterns)
+	str += "\n  " + upper->as_string ();
+    }
+
+  return str;
+}
+
+std::string
+SlicePattern::as_string () const
+{
+  return "SlicePattern: " + items->as_string ();
+}
+
 std::string
 AltPattern::as_string () const
 {
@@ -366,6 +402,18 @@ GroupedExpr::accept_vis (ASTVisitor &vis)
   vis.visit (*this);
 }
 
+void
+SlicePatternItemsNoRest::accept_vis (ASTVisitor &vis)
+{
+  vis.visit (*this);
+}
+
+void
+SlicePatternItemsHasRest::accept_vis (ASTVisitor &vis)
+{
+  vis.visit (*this);
+}
+
 void
 SlicePattern::accept_vis (ASTVisitor &vis)
 {