gccrs: Add lowering for if-let expressions

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-expr.cc
	(TypeCheckExpr::visit): Add implementation for IfLetExprConseqElse.
	* typecheck/rust-hir-type-check-expr.h:
	(TypeCheckExpr::visit): Remove stub implementation for IfLetExprConseqElse.
	* hir/rust-ast-lower-expr.cc
	(ASTLoweringExpr::visit): Lower IfLetExpr{,ConseqElse}.
	* hir/rust-ast-lower-expr.h:
	(ASTLoweringExpr::visit): Likewise.
	* hir/rust-ast-lower-block.h
	(ASTLoweringIfLetBlock::visit): Lower IfLetExprConseqElse.
	(ASTLoweringExprWithBlock::visit): Likewise.
	* hir/rust-ast-lower.cc
	(ASTLoweringIfLetBlock::visit): Lower IfLetExprConseqElse.
	* hir/tree/rust-hir-expr.h
	(IfLetExprConseqElse::IfLetExprConseqElse): Make constructor more general.
	(IfLetExprConseqElse::vis_else_block): Add.
	(IfLetExprConseqElse::get_else_block): Add.
	* resolve/rust-ast-resolve-expr.cc
	(ResolveExpr::visit): Add IfLetExprConseqElse visitor.
	* resolve/rust-ast-resolve-expr.h
	(ResolveExpr::visit): Add IfLetExprConseqElse visitor.

gcc/testsuite/ChangeLog:

	* rust/compile/if_let_expr.rs: Increase test coverage.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

10 files changed, 130 insertions, 5 deletions

diff --git a/gcc/rust/hir/rust-ast-lower-block.h b/gcc/rust/hir/rust-ast-lower-block.h
index a12fd87..a4d6069 100644
--- a/gcc/rust/hir/rust-ast-lower-block.h
+++ b/gcc/rust/hir/rust-ast-lower-block.h
@@ -130,6 +130,8 @@ public:
 
   void visit (AST::IfLetExpr &expr) override;
 
+  void visit (AST::IfLetExprConseqElse &expr) override;
+
 private:
   ASTLoweringIfLetBlock () : ASTLoweringBase (), translated (nullptr) {}
 
@@ -172,6 +174,11 @@ public:
     translated = ASTLoweringIfLetBlock::translate (&expr);
   }
 
+  void visit (AST::IfLetExprConseqElse &expr) override
+  {
+    translated = ASTLoweringIfLetBlock::translate (&expr);
+  }
+
   void visit (AST::BlockExpr &expr) override
   {
     translated = ASTLoweringBlock::translate (&expr, &terminated);
diff --git a/gcc/rust/hir/rust-ast-lower-expr.cc b/gcc/rust/hir/rust-ast-lower-expr.cc
index c65b08e..31b7f0f 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.cc
+++ b/gcc/rust/hir/rust-ast-lower-expr.cc
@@ -104,6 +104,18 @@ ASTLoweringExpr::visit (AST::IfExprConseqElse &expr)
 }
 
 void
+ASTLoweringExpr::visit (AST::IfLetExpr &expr)
+{
+  translated = ASTLoweringIfLetBlock::translate (&expr);
+}
+
+void
+ASTLoweringExpr::visit (AST::IfLetExprConseqElse &expr)
+{
+  translated = ASTLoweringIfLetBlock::translate (&expr);
+}
+
+void
 ASTLoweringExpr::visit (AST::BlockExpr &expr)
 {
   translated = ASTLoweringBlock::translate (&expr, &terminated);
diff --git a/gcc/rust/hir/rust-ast-lower-expr.h b/gcc/rust/hir/rust-ast-lower-expr.h
index d3e9532414..5b86ea2 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.h
+++ b/gcc/rust/hir/rust-ast-lower-expr.h
@@ -78,6 +78,8 @@ public:
   void visit (AST::TupleExpr &expr) override;
   void visit (AST::IfExpr &expr) override;
   void visit (AST::IfExprConseqElse &expr) override;
+  void visit (AST::IfLetExpr &expr) override;
+  void visit (AST::IfLetExprConseqElse &expr) override;
   void visit (AST::BlockExpr &expr) override;
   void visit (AST::UnsafeBlockExpr &expr) override;
   void visit (AST::PathInExpression &expr) override;
diff --git a/gcc/rust/hir/rust-ast-lower.cc b/gcc/rust/hir/rust-ast-lower.cc
index c9d5d01..cf5b75a 100644
--- a/gcc/rust/hir/rust-ast-lower.cc
+++ b/gcc/rust/hir/rust-ast-lower.cc
@@ -227,6 +227,40 @@ ASTLoweringIfLetBlock::visit (AST::IfLetExpr &expr)
 				   expr.get_locus ());
 }
 
+void
+ASTLoweringIfLetBlock::visit (AST::IfLetExprConseqElse &expr)
+{
+  std::vector<std::unique_ptr<HIR::Pattern>> patterns;
+  for (auto &pattern : expr.get_patterns ())
+    {
+      HIR::Pattern *ptrn = ASTLoweringPattern::translate (pattern.get ());
+      patterns.push_back (std::unique_ptr<HIR::Pattern> (ptrn));
+    }
+  HIR::Expr *value_ptr
+    = ASTLoweringExpr::translate (expr.get_value_expr ().get ());
+
+  bool ignored_terminated = false;
+  HIR::BlockExpr *block
+    = ASTLoweringBlock::translate (expr.get_if_block ().get (),
+				   &ignored_terminated);
+
+  HIR::ExprWithBlock *else_block
+    = ASTLoweringExprWithBlock::translate (expr.get_else_block ().get (),
+					   &ignored_terminated);
+
+  rust_assert (else_block);
+
+  auto crate_num = mappings->get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				 mappings->get_next_hir_id (crate_num),
+				 UNKNOWN_LOCAL_DEFID);
+
+  translated = new HIR::IfLetExprConseqElse (
+    mapping, std::move (patterns), std::unique_ptr<HIR::Expr> (value_ptr),
+    std::unique_ptr<HIR::BlockExpr> (block),
+    std::unique_ptr<HIR::ExprWithBlock> (else_block), expr.get_locus ());
+}
+
 // rust-ast-lower-struct-field-expr.h
 
 void
diff --git a/gcc/rust/hir/tree/rust-hir-expr.h b/gcc/rust/hir/tree/rust-hir-expr.h
index 3c9db9f..47b9897 100644
--- a/gcc/rust/hir/tree/rust-hir-expr.h
+++ b/gcc/rust/hir/tree/rust-hir-expr.h
@@ -3457,7 +3457,7 @@ public:
     Analysis::NodeMapping mappings,
     std::vector<std::unique_ptr<Pattern> > match_arm_patterns,
     std::unique_ptr<Expr> value, std::unique_ptr<BlockExpr> if_block,
-    std::unique_ptr<BlockExpr> else_block, Location locus)
+    std::unique_ptr<ExprWithBlock> else_block, Location locus)
     : IfLetExpr (std::move (mappings), std::move (match_arm_patterns),
 		 std::move (value), std::move (if_block), locus),
       else_block (std::move (else_block))
@@ -3489,6 +3489,10 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
+  void vis_else_block (HIRFullVisitor &vis) { else_block->accept_vis (vis); }
+
+  ExprWithBlock *get_else_block () { return else_block.get (); }
+
 protected:
   /* Use covariance to implement clone function as returning this object rather
    * than base */
diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.cc b/gcc/rust/resolve/rust-ast-resolve-expr.cc
index 339fd8a..41ce9c9 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.cc
@@ -217,6 +217,37 @@ ResolveExpr::visit (AST::IfLetExpr &expr)
 }
 
 void
+ResolveExpr::visit (AST::IfLetExprConseqElse &expr)
+{
+  ResolveExpr::go (expr.get_value_expr ().get (), prefix, canonical_prefix);
+
+  NodeId scope_node_id = expr.get_node_id ();
+  resolver->get_name_scope ().push (scope_node_id);
+  resolver->get_type_scope ().push (scope_node_id);
+  resolver->get_label_scope ().push (scope_node_id);
+  resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
+  resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
+  resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
+
+  // We know expr.get_patterns () has one pattern at most
+  // so there's no reason to handle it like an AltPattern.
+  std::vector<PatternBinding> bindings
+    = {PatternBinding (PatternBoundCtx::Product, std::set<Identifier> ())};
+
+  for (auto &pattern : expr.get_patterns ())
+    {
+      PatternDeclaration::go (pattern.get (), Rib::ItemType::Var, bindings);
+    }
+
+  ResolveExpr::go (expr.get_if_block ().get (), prefix, canonical_prefix);
+  ResolveExpr::go (expr.get_else_block ().get (), prefix, canonical_prefix);
+
+  resolver->get_name_scope ().pop ();
+  resolver->get_type_scope ().pop ();
+  resolver->get_label_scope ().pop ();
+}
+
+void
 ResolveExpr::visit (AST::BlockExpr &expr)
 {
   NodeId scope_node_id = expr.get_node_id ();
diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.h b/gcc/rust/resolve/rust-ast-resolve-expr.h
index 7b0beaf..896617cc 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.h
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.h
@@ -51,6 +51,7 @@ public:
   void visit (AST::IfExpr &expr) override;
   void visit (AST::IfExprConseqElse &expr) override;
   void visit (AST::IfLetExpr &expr) override;
+  void visit (AST::IfLetExprConseqElse &expr) override;
   void visit (AST::BlockExpr &expr) override;
   void visit (AST::UnsafeBlockExpr &expr) override;
   void visit (AST::ArrayElemsValues &elems) override;
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.cc b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
index 4352dc9..6594068 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
@@ -494,6 +494,42 @@ TypeCheckExpr::visit (HIR::IfLetExpr &expr)
 }
 
 void
+TypeCheckExpr::visit (HIR::IfLetExprConseqElse &expr)
+{
+  TyTy::BaseType *scrutinee_tyty
+    = TypeCheckExpr::Resolve (expr.get_scrutinee_expr ().get ());
+
+  for (auto &pattern : expr.get_patterns ())
+    {
+      TyTy::BaseType *kase_arm_ty
+	= TypeCheckPattern::Resolve (pattern.get (), scrutinee_tyty);
+
+      unify_site (expr.get_mappings ().get_hirid (),
+		  TyTy::TyWithLocation (scrutinee_tyty),
+		  TyTy::TyWithLocation (kase_arm_ty, pattern->get_locus ()),
+		  expr.get_locus ());
+    }
+
+  auto if_blk_resolved = TypeCheckExpr::Resolve (expr.get_if_block ());
+  auto else_blk_resolved = TypeCheckExpr::Resolve (expr.get_else_block ());
+
+  if (if_blk_resolved->get_kind () == TyTy::NEVER)
+    infered = else_blk_resolved;
+  else if (else_blk_resolved->get_kind () == TyTy::NEVER)
+    infered = if_blk_resolved;
+  else
+    {
+      infered = unify_site (
+	expr.get_mappings ().get_hirid (),
+	TyTy::TyWithLocation (if_blk_resolved,
+			      expr.get_if_block ()->get_locus ()),
+	TyTy::TyWithLocation (else_blk_resolved,
+			      expr.get_else_block ()->get_locus ()),
+	expr.get_locus ());
+    }
+}
+
+void
 TypeCheckExpr::visit (HIR::UnsafeBlockExpr &expr)
 {
   infered = TypeCheckExpr::Resolve (expr.get_block_expr ().get ());
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index 68c09c7..2ff320d 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -45,6 +45,7 @@ public:
   void visit (HIR::IfExpr &expr) override;
   void visit (HIR::IfExprConseqElse &expr) override;
   void visit (HIR::IfLetExpr &expr) override;
+  void visit (HIR::IfLetExprConseqElse &) override;
   void visit (HIR::BlockExpr &expr) override;
   void visit (HIR::UnsafeBlockExpr &expr) override;
   void visit (HIR::ArrayIndexExpr &expr) override;
@@ -75,7 +76,6 @@ public:
   void visit (HIR::RangeToInclExpr &) override {}
   void visit (HIR::WhileLetLoopExpr &) override {}
   void visit (HIR::ForLoopExpr &) override {}
-  void visit (HIR::IfLetExprConseqElse &) override {}
   void visit (HIR::AwaitExpr &) override {}
   void visit (HIR::AsyncBlockExpr &) override {}
 
diff --git a/gcc/testsuite/rust/compile/if_let_expr.rs b/gcc/testsuite/rust/compile/if_let_expr.rs
index 31e301f..ffa367b 100644
--- a/gcc/testsuite/rust/compile/if_let_expr.rs
+++ b/gcc/testsuite/rust/compile/if_let_expr.rs
@@ -1,12 +1,10 @@
-// { dg-options "-fsyntax-only" }
-
 pub enum Option<T> {
     None,
     Some(T),
 }
 
 fn main() {
-    let x = Option::Some(3);
+    let x = Option::Some(3); // { dg-warning "unused name" }
     let a = if let Option::Some(1) = x {
         1
     } else if x == Option::Some(2) {