Re: [PATCH for-4.14] golang/xenlight: sort cases in switch statement

[George Dunlap <George.Dunlap@xxxxxxxxxx>]

> On Jun 15, 2020, at 4:43 PM, Ian Jackson <ian.jackson@xxxxxxxxxx> wrote:
> 
> Nick Rosbrook writes ("[PATCH for-4.14] golang/xenlight: sort cases in switch 
> statement"):
>> The xenlight_golang_union_from_C function iterates over a dict to
>> construct a switch statement that marshals a C keyed union into a Go
>> type. Because python does not guarantee dict ordering across all
>> versions, this can result in the switch statement being generated in a
>> different order depending on the version of python used. For example,
>> running gengotypes.py with python2.7 and python3.6 will yield different
>> orderings.
>> 
>> Iterate over sorted(cases.items()) rather than cases.items() to fix
>> this.
>> 
>> This patch changes the ordering from what was previously checked-in, but
>> running gengotypes.py with different versions of python will now yield
>> the same result.
>> 
>> Signed-off-by: Nick Rosbrook <rosbrookn@xxxxxxxxxxxx>
>> ---
>> Andrew reported this in [1], so I intend this as a build fix for 4.14.
>> 
>> [1] 
>> https://lists.xenproject.org/archives/html/xen-devel/2020-06/msg00881.html
>> ---
>> tools/golang/xenlight/gengotypes.py  |  2 +-
>> tools/golang/xenlight/helpers.gen.go | 32 ++++++++++++++--------------
>> 2 files changed, 17 insertions(+), 17 deletions(-)
>> 
>> diff --git a/tools/golang/xenlight/gengotypes.py 
>> b/tools/golang/xenlight/gengotypes.py
>> index ecca59745f..557fecd07b 100644
>> --- a/tools/golang/xenlight/gengotypes.py
>> +++ b/tools/golang/xenlight/gengotypes.py
>> @@ -379,7 +379,7 @@ def xenlight_golang_union_from_C(ty = None, union_name = 
>> '', struct_name = ''):
>> 
>>     # Create switch statement to determine which 'union element'
>>     # to populate in the Go struct.
>> -    for case_name, case_tuple in cases.items():
>> +    for case_name, case_tuple in sorted(cases.items()):
>>         (case_val, case_type) = case_tuple
> 
> This part
> 
> Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> 
> But I don't think I have the right golang tools to verify the
> autogenerated code.  George, can you check that this patch is right,
> and/or do the commit and rerun the generation ?

I can confirm that 1) rerunning this doesn’t cause any changes 2) the resulting 
code compiles.

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>

Since I’ve got it in my tree I’ll push it.