[edk2-devel] VariablePolicy: Final Changes Thread 2 - ECC & UnitTest
Andrew Fish via groups.io
afish=apple.com at groups.io
Wed Oct 7 14:27:47 UTC 2020
For case 1 I thought the size had to be > 8 bytes, not just a struct? Maybe that is compiler specific?
> On Oct 7, 2020, at 6:43 AM, Laszlo Ersek <lersek at redhat.com> wrote:
>
> On 10/07/20 03:46, Michael D Kinney wrote:
>>
>> Bret,
>>
>> Initializing variable in declaration for structures and arrays
>> introduces use of intrinsics. Since it is possible for unit test
>> sources to be used for both host and target tests, I recommend we
>> continue to follow the EDK II coding style for unit tests to support
>> maximum compatibility and code reuse.
>>
>> Using a module global variable with initializers instead of
>> initializing a local declaration is the same amount of work, so I do
>> not believe that will result in fewer tests.
>>
>> I agree it is useful to have the test data next to the test code. This
>> can be accomplished by breaking up into more files so the test data is
>> immediately above the test function the test data is used. Does ECC
>> raise an error if a module global is placed between 2 functions? A
>> 2nd approach to put the module global immediately above the test
>> function the test data is used.
>
> Consider the following example structure type, for the sake of
> discussion:
>
> typedef struct {
> UINT32 Value;
> } TEST_DATA;
>
>
> * Case#1: block scope, automatic storage duration
>
> EFI_STATUS
> FoobarTest (
> VOID
> )
> {
> TEST_DATA TestData = { 42 };
> // ...
> }
>
> Problem: uses intrinsics.
>
>
> * Case#2: file scope, static storage duration.
>
> STATIC CONST TEST_DATA mTestData = { 42 };
>
> EFI_STATUS
> FoobarTest (
> VOID
> )
> {
> // ...
> }
>
> Problem: either "mTestData" is textually far from FoobarTest(), or -- if
> we keep them close to each other -- we mix variable definitions with
> function definitions, at file scope.
>
>
> * Case #3: block scope, static storage duration.
>
> EFI_STATUS
> FoobarTest (
> VOID
> )
> {
> STATIC CONST TEST_DATA TestData = { 42 };
> // ...
> }
>
> Problem: there should be none. Does not involve intrinsics, and the
> object definition is part of the function's scope.
>
>
> If ECC does not recognize case#3 as valid, then that is an *ECC bug*.
>
> ECC has no reason to prevent case#3, as case#3 does not involve
> intrinsics, and is a generally valid and useful C language construct (it
> combines the life cycle of case#2 with the visibility of case#1).
>
> Again, if ECC rejects case#3, that's *definitely* a bug in ECC, and we
> should fix it first. Given that ECC includes a full-blown C language
> parser, the fix should not be too difficult -- check if the declaration
> has the "static" storage-class specifier.
>
> ... In fact, I think that purely CONST-qualifying TestData might suffice
> for shutting up ECC. See the following in
> "BaseTools/Source/Python/Ecc/c.py", method
> "CheckFuncLayoutLocalVariable":
>
>> for Result in ResultSet:
>> if len(Result[1]) > 0 and 'CONST' not in Result[3]:
>> PrintErrorMsg(ERROR_C_FUNCTION_LAYOUT_CHECK_NO_INIT_OF_VARIABLE, 'Variable Name: %s' % Result[0], FileTable, Result[2])
>
> So case#3 should work through that avenue already, because case#3 has
> CONST *too*.
>
> Now, in case#3, if "TestData" needs to undergo modifications, and so
> CONST is not immediately desirable, that's solvable:
>
> EFI_STATUS
> FoobarTest (
> VOID
> )
> {
> STATIC CONST TEST_DATA TestDataTemplate = { 42 };
> TEST_DATA TestData;
>
> CopyMem (&TestData, TestDataTemplate, sizeof (TEST_DATA));
> // ...
> }
>
> Thanks
> Laszlo
>
>>
>> Best regards,
>>
>> Mike
>>
>> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Bret Barkelew via groups.io
>> Sent: Tuesday, October 6, 2020 5:28 PM
>> To: devel at edk2.groups.io
>> Subject: [edk2-devel] VariablePolicy: Final Changes Thread 2 - ECC & UnitTest
>>
>> Ive worked through all the ECC issues with Variable Policy (AND the UnitTests) on this branch:
>> Commits · corthon/edk2 (github.com)<https://github.com/corthon/edk2/commits/var_policy_dev_submission_v8>
>>
>> I even wrote the Main() entry point lib that Laszlo suggested (it works rather nicely):
>> TEMP: Staging for HostTest entry point · corthon/edk2 at 4ce5210 (github.com)<https://github.com/corthon/edk2/commit/4ce52108b3e1bcb2ba78995be94c3949fe647eda>
>>
>> However, theres one that I just cant get past and I would like to take it up with the community. I dont think that UnitTests should have to deal with the
cant initialize variables in declaration
check. Almost none of the solutions that I tested worked, and the ones that did were too cumbersome. They failed on two key points that are important for test writing:
>>
>> * They were annoying to write ===> fewer tests.
>> * They moved even more of the test case data away from the test ===> harder to read tests.
>>
>> I would like to move for an exception for unit tests (or at least host-based unit tests), but I dont know how to accomplish that from a technical standpoint.
>>
>> Thoughts?
>>
>> - Bret
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
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