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* [binutils-gdb] Reimplement Rust slice printing
@ 2022-04-15 17:35 Tom Tromey
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From: Tom Tromey @ 2022-04-15 17:35 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=506ec52e8805d8edd538d6bd11750489a8c8bbee
commit 506ec52e8805d8edd538d6bd11750489a8c8bbee
Author: Tom Tromey <tom@tromey.com>
Date: Fri Mar 25 13:36:53 2022 -0600
Reimplement Rust slice printing
The current nightly Rust compiler (aka 1.61) added better DWARF
representation for unsized types. Fixing this is PR rust/21466; but
the code is actually the same as what is required to make slice
printing more useful, which is PR rust/23871. This patch implements
this. I tested this against various Rust compilers: 1.48, current
stable, current beta, and current nightly.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=21466
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23871
Diff:
---
gdb/rust-lang.c | 85 ++++++++++++++++++++++++++------------
gdb/testsuite/gdb.rust/simple.exp | 3 +-
gdb/testsuite/gdb.rust/unsized.exp | 8 ++++
gdb/testsuite/gdb.rust/unsized.rs | 2 +
4 files changed, 71 insertions(+), 27 deletions(-)
diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index fdd6e3fbdbb..d4a221abb08 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -159,10 +159,19 @@ rust_tuple_struct_type_p (struct type *type)
static bool
rust_slice_type_p (struct type *type)
{
- return (type->code () == TYPE_CODE_STRUCT
- && type->name () != NULL
- && (strncmp (type->name (), "&[", 2) == 0
- || strcmp (type->name (), "&str") == 0));
+ if (type->code () == TYPE_CODE_STRUCT
+ && type->name () != NULL
+ && type->num_fields () == 2)
+ {
+ /* The order of fields doesn't matter. While it would be nice
+ to check for artificiality here, the Rust compiler doesn't
+ emit this information. */
+ const char *n1 = type->field (0).name ();
+ const char *n2 = type->field (1).name ();
+ return ((streq (n1, "data_ptr") && streq (n2, "length"))
+ || (streq (n2, "data_ptr") && streq (n1, "length")));
+ }
+ return false;
}
/* Return true if TYPE is a range type, otherwise false. */
@@ -296,19 +305,57 @@ rust_language::printstr (struct ui_file *stream, struct type *type,
\f
-/* Helper function to print a string slice. */
+static const struct generic_val_print_decorations rust_decorations =
+{
+ /* Complex isn't used in Rust, but we provide C-ish values just in
+ case. */
+ "",
+ " + ",
+ " * I",
+ "true",
+ "false",
+ "()",
+ "[",
+ "]"
+};
+
+/* Helper function to print a slice. */
static void
-rust_val_print_str (struct ui_file *stream, struct value *val,
- const struct value_print_options *options)
+rust_val_print_slice (struct value *val, struct ui_file *stream, int recurse,
+ const struct value_print_options *options)
{
struct value *base = value_struct_elt (&val, {}, "data_ptr", NULL,
"slice");
struct value *len = value_struct_elt (&val, {}, "length", NULL, "slice");
- val_print_string (TYPE_TARGET_TYPE (value_type (base)), "UTF-8",
- value_as_address (base), value_as_long (len), stream,
- options);
+ struct type *type = check_typedef (value_type (val));
+ if (strcmp (type->name (), "&str") == 0)
+ val_print_string (TYPE_TARGET_TYPE (value_type (base)), "UTF-8",
+ value_as_address (base), value_as_long (len), stream,
+ options);
+ else
+ {
+ LONGEST llen = value_as_long (len);
+
+ type_print (value_type (val), "", stream, -1);
+ gdb_printf (stream, " ");
+
+ if (llen == 0)
+ gdb_printf (stream, "[]");
+ else
+ {
+ struct type *elt_type = TYPE_TARGET_TYPE (value_type (base));
+ struct type *array_type = lookup_array_range_type (elt_type, 0,
+ llen - 1);
+ struct value *array = allocate_value_lazy (array_type);
+ VALUE_LVAL (array) = lval_memory;
+ set_value_address (array, value_as_address (base));
+ value_fetch_lazy (array);
+ generic_value_print (array, stream, recurse, options,
+ &rust_decorations);
+ }
+ }
}
/* See rust-lang.h. */
@@ -322,9 +369,9 @@ rust_language::val_print_struct
int first_field;
struct type *type = check_typedef (value_type (val));
- if (rust_slice_type_p (type) && strcmp (type->name (), "&str") == 0)
+ if (rust_slice_type_p (type))
{
- rust_val_print_str (stream, val, options);
+ rust_val_print_slice (val, stream, recurse, options);
return;
}
@@ -468,20 +515,6 @@ rust_language::print_enum (struct value *val, struct ui_file *stream,
gdb_puts ("}", stream);
}
-static const struct generic_val_print_decorations rust_decorations =
-{
- /* Complex isn't used in Rust, but we provide C-ish values just in
- case. */
- "",
- " + ",
- " * I",
- "true",
- "false",
- "()",
- "[",
- "]"
-};
-
/* See language.h. */
void
diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
index b6f2993c381..246aff634d3 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -314,7 +314,8 @@ proc test_one_slice {svar length base range} {
with_test_prefix $range {
global hex
- set result " = &\\\[.*\\\] \\{data_ptr: $hex, length: $length\\}"
+ # Just accept any array here.
+ set result " = &\\\[.*\\\] \\\[.*\\\]"
gdb_test "print $svar" $result
gdb_test "print &${base}\[${range}\]" $result
diff --git a/gdb/testsuite/gdb.rust/unsized.exp b/gdb/testsuite/gdb.rust/unsized.exp
index 76d0bbb739b..67ee49d0935 100644
--- a/gdb/testsuite/gdb.rust/unsized.exp
+++ b/gdb/testsuite/gdb.rust/unsized.exp
@@ -32,3 +32,11 @@ if {![runto ${srcfile}:$line]} {
}
gdb_test "ptype us" " = .*V<\\\[u8\\\]>.*"
+
+set v [split [rust_compiler_version] .]
+# The necessary debuginfo generation landed in 1.60, but had a bug
+# that was fixed in 1.61.
+if {[lindex $v 0] > 1 || [lindex $v 1] >= 61} {
+ gdb_test "print us2" " = .*Box<.*> \\\[1, 2, 3\\\]"
+ gdb_test "ptype us2" "type = .*"
+}
diff --git a/gdb/testsuite/gdb.rust/unsized.rs b/gdb/testsuite/gdb.rust/unsized.rs
index f4897d6b8f8..af3192e8407 100644
--- a/gdb/testsuite/gdb.rust/unsized.rs
+++ b/gdb/testsuite/gdb.rust/unsized.rs
@@ -28,6 +28,8 @@ fn ignore<T>(x: T) { }
fn main() {
let v: Box<V<[u8; 3]>> = Box::new(V { data: [1, 2, 3] });
let us: Box<Unsized> = v;
+ let v2 : Box<[u8; 3]> = Box::new([1, 2, 3]);
+ let us2 : Box<[u8]> = v2;
ignore(us); // set breakpoint here
}
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