Add num_children method to some gdb pretty-printersgdb doesn't have a way to know when an object hasn't yet been initialized, and in this case, if a pretty-printer returns an absurd number of children, this can result in apparent hangs in some modes. This came up specifically with DAP, see this bug report:https://sourceware.org/bugzilla/show_bug.cgi?id=33594This patch (mostly) addresses this potential issue in the Rust pretty-printers, by adding 'num_children' methods.  In particular a method like this is added when the number of children is variable and also relatively easy to compute.  (I.e., I didn't attempt the btree printers.)Supplying num_children is good for DAP regardless of the initialization problem, because DAP requires a count of child objects and this is more efficient than enumerating the children, which is gdb's fallback approach.

Rollup of 7 pull requestsSuccessful merges: -#145656 (Stabilize s390x `vector` target feature and `is_s390x_feature_detected!` macro) -#147043 (Add default sanitizers to TargetOptions) -#147803 (Add -Zannotate-moves for profiler visibility of move/copy operations (codegen)) -#147912 ([rustdoc] Gracefully handle error in case we cannot run the compiler in doctests) -#148540 (Minor fixes to StdNonZeroNumberProvider for gdb) -#148541 (Add num_children method to some gdb pretty-printers) -#148549 (Fix broken qemu-cskyv2 link)Failed merges: -#147586 (std-detect: improve detect macro docs)r? `@ghost``@rustbot` modify labels: rollup

Add num_children method to some gdb pretty-printersgdb doesn't have a way to know when an object hasn't yet been initialized, and in this case, if a pretty-printer returns an absurd number of children, this can result in apparent hangs in some modes. This came up specifically with DAP, see this bug report:https://sourceware.org/bugzilla/show_bug.cgi?id=33594This patch (mostly) addresses this potential issue in the Rust pretty-printers, by adding 'num_children' methods.  In particular a method like this is added when the number of children is variable and also relatively easy to compute.  (I.e., I didn't attempt the btree printers.)Supplying num_children is good for DAP regardless of the initialization problem, because DAP requires a count of child objects and this is more efficient than enumerating the children, which is gdb's fallback approach.

Rollup of 7 pull requestsSuccessful merges: -#143037 (Make named asm_labels lint not trigger on hexagon register spans) -#147043 (Add default sanitizers to TargetOptions) -#147586 (std-detect: improve detect macro docs) -#147912 ([rustdoc] Gracefully handle error in case we cannot run the compiler in doctests) -#148540 (Minor fixes to StdNonZeroNumberProvider for gdb) -#148541 (Add num_children method to some gdb pretty-printers) -#148549 (Fix broken qemu-cskyv2 link)Failed merges: -#147935 (Add LLVM realtime sanitizer)r? `@ghost``@rustbot` modify labels: rollup