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[PATCH] Add support for the sizeof function in Rust
- From: Manish Goregaokar <manish at mozilla dot com>
- To: gdb-patches at sourceware dot org
- Cc: Tom Tromey <tom at tromey dot com>
- Date: Sat, 29 Oct 2016 06:10:11 -0700
- Subject: [PATCH] Add support for the sizeof function in Rust
- Authentication-results: sourceware.org; auth=none
`sizeof` isn't currently a thing in Rust (there is `mem::size_of()`,
but it's an intrinsic and can't be called via debugging even if it
were used by the program). `sizeof` is a keyword so Rust functions by
that name cannot exist. This parses `sizeof(thing)` as a
`UNOP_SIZEOF`, which automatically is handled by the C expression
handler.
We already support indexing of pointers the C way to make it easier to
debug vectors, even though Rust doesn't have an Index implementation
on pointers. This is in the same spirit; sizeof is needed whilst
debugging and we should avoid making the user `set language c` in this
process.
The expression could be `sizeof foo` instead of `sizeof(foo)`. I feel
the latter is better because it's closer to how `mem::size_of` works.
Not bent on keeping it that way, the former approach has the benefit
of not introducing ambiguities in the syntax and not removing the
ability to call non-rust functions named "sizeof".
From: Manish Goregaokar <manish@mozilla.com>
Date: Sat, 29 Oct 2016 05:55:58 -0700
Subject: [PATCH] Add support for the sizeof function in Rust
2016-10-29 Manish Goregaokar <manish@mozilla.com>
gdb/ChangeLog:
* rust-exp.y: Parse `sizeof(exp)` as `UNOP_SIZEOF`
gdb/testsuite/ChangeLog:
* gdb.rust/simple.exp: Add tests for `sizeof(expr)`
---
gdb/rust-exp.y | 8 ++++++--
gdb/testsuite/gdb.rust/simple.exp | 4 +++-
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/gdb/rust-exp.y b/gdb/rust-exp.y
index 6dc4704..dffccd0 100644
--- a/gdb/rust-exp.y
+++ b/gdb/rust-exp.y
@@ -276,6 +276,7 @@ struct rust_op
%token <voidval> KW_EXTERN
%token <voidval> KW_CONST
%token <voidval> KW_FN
+%token <voidval> KW_SIZEOF
/* Operator tokens. */
%token <voidval> DOTDOT
@@ -371,7 +372,7 @@ expr:
| array_expr
| idx_expr
| range_expr
-| unop_expr
+| unop_expr /* Must precede call_expr because of ambiguity with sizeof. */
| binop_expr
| paren_expr
| call_expr
@@ -577,7 +578,8 @@ unop_expr:
| '&' KW_MUT expr %prec UNARY
{ $$ = ast_unary (UNOP_ADDR, $3); }
-
+| KW_SIZEOF '(' expr ')' %prec UNARY
+ { $$ = ast_unary (UNOP_SIZEOF, $3); }
;
binop_expr:
@@ -872,6 +874,7 @@ static const struct token_info identifier_tokens[] =
{ "true", KW_TRUE, OP_NULL },
{ "extern", KW_EXTERN, OP_NULL },
{ "fn", KW_FN, OP_NULL },
+ { "sizeof", KW_SIZEOF, OP_NULL },
};
/* Operator tokens, sorted longest first. */
@@ -2194,6 +2197,7 @@ convert_ast_to_expression (struct parser_state *state,
case UNOP_COMPLEMENT:
case UNOP_IND:
case UNOP_ADDR:
+ case UNOP_SIZEOF:
convert_ast_to_expression (state, operation->left.op, top);
write_exp_elt_opcode (state, operation->opcode);
break;
diff --git a/gdb/testsuite/gdb.rust/simple.exp
b/gdb/testsuite/gdb.rust/simple.exp
index 075bff7..9ab4b70 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -33,6 +33,7 @@ if {![runto ${srcfile}:$line]} {
gdb_test "print a" " = \\(\\)"
gdb_test "ptype a" " = \\(\\)"
+gdb_test "print sizeof(a)" " = 0"
gdb_test "print b" " = \\\[\\\]"
gdb_test "ptype b" " = \\\[i32; 0\\\]"
@@ -41,6 +42,7 @@ gdb_test "print *(&b as *const \[i32; 0_0\])" " = \\\[\\\]"
gdb_test "print c" " = 99"
gdb_test "ptype c" " = i32"
+gdb_test "print sizeof(c)" " = 4"
gdb_test "print c = 87" " = \\(\\)"
gdb_test "print c" " = 87"
@@ -124,7 +126,7 @@ gdb_test "print nosuchsymbol" \
gdb_test "print e" " = simple::MoreComplicated::Two\\(73\\)"
gdb_test "print e2" \
" = simple::MoreComplicated::Four\\{this: true, is: 8, a: 109
'm', struct_: 100, variant: 10\\}"
-
+gdb_test "print sizeof(e)" " = 24"
gdb_test_sequence "ptype e" "" {
" = enum simple::MoreComplicated \\{"
" One,"
--
2.10.1