Re: Using unsafe blocks in let expressions

[Mark Wielaard <mark@klomp.org>]

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On Wed, Jul 21, 2021 at 11:09:38PM +0200, Mark Wielaard wrote:
> +  Location locus;
> +  if (!pratt_parse)
> +    {
> +      Location locus = lexer.peek_token ()->get_locus ();

Oops, shadowed locus.  Fixed patch attached, and also at
https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=let-unsafe



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From a7329b7fc0190920a9cf8bec77e34f2866b8af94 Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Wed, 21 Jul 2021 22:41:04 +0200
Subject: [PATCH] unsafe blocks can be used in expressions

To use an unsafe block expression handle it in null_denotation for the
pratt parser. Adjust parse_unsafe_block_expr to take a pratt_parse
bool that defaults to false.
---
 gcc/rust/parse/rust-parse-impl.h | 15 ++++++++++++---
 gcc/rust/parse/rust-parse.h      |  5 +++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index eedc76db43e..bdf1e09a029 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -8704,10 +8704,17 @@ Parser<ManagedTokenSource>::parse_async_block_expr (AST::AttrVec outer_attrs)
 // Parses an unsafe block expression.
 template <typename ManagedTokenSource>
 std::unique_ptr<AST::UnsafeBlockExpr>
-Parser<ManagedTokenSource>::parse_unsafe_block_expr (AST::AttrVec outer_attrs)
+Parser<ManagedTokenSource>::parse_unsafe_block_expr (AST::AttrVec outer_attrs,
+						     bool pratt_parse)
 {
-  Location locus = lexer.peek_token ()->get_locus ();
-  skip_token (UNSAFE);
+  Location locus;
+  if (!pratt_parse)
+    {
+      locus = lexer.peek_token ()->get_locus ();
+      skip_token (UNSAFE);
+    }
+  else
+    locus = lexer.peek_token ()->get_locus () - 1;
 
   // parse block expression (required)
   std::unique_ptr<AST::BlockExpr> block_expr = parse_block_expr ();
@@ -12823,6 +12830,8 @@ Parser<ManagedTokenSource>::null_denotation (const_TokenPtr tok,
     case LEFT_SQUARE:
       // array definition expr (not indexing)
       return parse_array_expr (std::move (outer_attrs), true);
+    case UNSAFE:
+      return parse_unsafe_block_expr (std::move (outer_attrs), true);
     default:
       if (!restrictions.expr_can_be_null)
 	add_error (Error (tok->get_locus (),
diff --git a/gcc/rust/parse/rust-parse.h b/gcc/rust/parse/rust-parse.h
index 1cd85eae8c2..1c7bd781b3f 100644
--- a/gcc/rust/parse/rust-parse.h
+++ b/gcc/rust/parse/rust-parse.h
@@ -504,8 +504,6 @@ private:
   AST::LoopLabel parse_loop_label ();
   std::unique_ptr<AST::AsyncBlockExpr>
   parse_async_block_expr (AST::AttrVec outer_attrs = AST::AttrVec ());
-  std::unique_ptr<AST::UnsafeBlockExpr>
-  parse_unsafe_block_expr (AST::AttrVec outer_attrs = AST::AttrVec ());
   std::unique_ptr<AST::GroupedExpr> parse_grouped_expr (AST::AttrVec outer_attrs
 							= AST::AttrVec ());
   std::unique_ptr<AST::ClosureExpr> parse_closure_expr (AST::AttrVec outer_attrs
@@ -522,6 +520,9 @@ private:
   std::unique_ptr<AST::ContinueExpr>
   parse_continue_expr (AST::AttrVec outer_attrs = AST::AttrVec (),
 		       bool pratt_parse = false);
+  std::unique_ptr<AST::UnsafeBlockExpr>
+  parse_unsafe_block_expr (AST::AttrVec outer_attrs = AST::AttrVec (),
+			   bool pratt_parse = false);
   std::unique_ptr<AST::ArrayExpr> parse_array_expr (AST::AttrVec outer_attrs
 						    = AST::AttrVec (),
 						    bool pratt_parse = false);
-- 
2.32.0