Print type name when printing Rust slice
Checks
| Context |
Check |
Description |
| linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 |
success
|
Testing passed
|
| linaro-tcwg-bot/tcwg_gdb_build--master-arm |
success
|
Testing passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-arm |
success
|
Testing passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 |
success
|
Testing passed
|
Commit Message
The recent change to how unsized Rust values are printed included a
small regression from past behavior. Previously, a slice's type would
be printed, like:
(gdb) print slice
$80 = &[i32] [3]
The patch changed this to just
(gdb) print slice
$80 = [3]
This patch restores the previous behavior.
---
gdb/rust-lang.c | 11 +++++++++++
gdb/testsuite/gdb.rust/simple.exp | 2 +-
gdb/testsuite/gdb.rust/unsized.exp | 2 +-
3 files changed, 13 insertions(+), 2 deletions(-)
Comments
On 3/11/24 11:14, Tom Tromey wrote:
> The recent change to how unsized Rust values are printed included a
> small regression from past behavior. Previously, a slice's type would
> be printed, like:
>
> (gdb) print slice
> $80 = &[i32] [3]
>
> The patch changed this to just
>
> (gdb) print slice
> $80 = [3]
>
> This patch restores the previous behavior.
> ---
> gdb/rust-lang.c | 11 +++++++++++
> gdb/testsuite/gdb.rust/simple.exp | 2 +-
> gdb/testsuite/gdb.rust/unsized.exp | 2 +-
> 3 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
> index ab537cc9752..d7265f72770 100644
> --- a/gdb/rust-lang.c
> +++ b/gdb/rust-lang.c
> @@ -476,6 +476,17 @@ rust_language::val_print_slice
> }
> }
>
> + /* Print the slice type here. This was gdb's historical behavior
> + (from before unsized types were generically handled) and helps
> + make it clear that the user is seeing a slice, not an array.
> + Only arrays must be handled as the other cases are handled by
> + value_print_inner. */
> + if (type->code () == TYPE_CODE_ARRAY)
> + {
> + type_print (orig_type, "", stream, -1);
> + gdb_printf (stream, " ");
> + }
Just for me education, how are slices represented in the GDB type
system, as opposed to arrays? What are the value types that
rust_language::val_print_slice expects to receive, other than
TYPE_CODE_ARRAY?
You can add my:
Reviewed-By: Simon Marchi <simon.marchi@efficios.com>
... although it's not worth much because I don't know this area.
Simon
>>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:
Simon> Just for me education, how are slices represented in the GDB type
Simon> system, as opposed to arrays? What are the value types that
Simon> rust_language::val_print_slice expects to receive, other than
Simon> TYPE_CODE_ARRAY?
Under the hood a slice is a structure holding a pointer and a length.
However to the Rust programmer these look somewhat like arrays. For
example, you can index into them like arrays.
rust_slice_type_p determines if something is "slice-like".
An "unsized" type is basically the same thing, but where the payload is
some object with an array at the end, like the C struct hack.
rust-lang.c calls these both "slice" at some spots, mainly because I
didn't understand this when I first wrote the code.
FWIW Ada has a similar concept but it is more general, because Ada has
multi-dimensional arrays and range types.
Tom
>>>>> "Tom" == Tom Tromey <tromey@adacore.com> writes:
Tom> The recent change to how unsized Rust values are printed included a
Tom> small regression from past behavior. Previously, a slice's type would
Tom> be printed, like:
Tom> (gdb) print slice
Tom> $80 = &[i32] [3]
Tom> The patch changed this to just
Tom> (gdb) print slice
Tom> $80 = [3]
Tom> This patch restores the previous behavior.
Oops, I almost forgot about this one.
I'm checking it in now.
Tom
@@ -476,6 +476,17 @@ rust_language::val_print_slice
}
}
+ /* Print the slice type here. This was gdb's historical behavior
+ (from before unsized types were generically handled) and helps
+ make it clear that the user is seeing a slice, not an array.
+ Only arrays must be handled as the other cases are handled by
+ value_print_inner. */
+ if (type->code () == TYPE_CODE_ARRAY)
+ {
+ type_print (orig_type, "", stream, -1);
+ gdb_printf (stream, " ");
+ }
+
value_print_inner (val, stream, recurse, options);
}
@@ -317,7 +317,7 @@ proc test_one_slice {svar length base range} {
global hex
# Just accept any array here.
- set result " = \\\[.*\\\]"
+ set result " = &\\\[.*\\\] \\\[.*\\\]"
gdb_test "print $svar" $result
gdb_test "print &${base}\[${range}\]" $result
@@ -33,6 +33,6 @@ if {![runto ${srcfile}:$line]} {
gdb_test "ptype us" " = .*V<\\\[u8\\\]>.*"
if {[rust_at_least 1.61]} {
- gdb_test "print us2" " = \\\[1, 2, 3\\\]"
+ gdb_test "print us2" " = .*u8.* \\\[1, 2, 3\\\]"
gdb_test "ptype us2" "type = .*"
}