Use logical operators for bool converions.

[rtakacs]

The explicit boolean type conversion (introduced by #2575) desn't work
with TizenRT if custom boolean representation is used. Of course,
TizenRT gives an opportunity to use the C99 standard boolean (that works
well if that is set).

I've replaced all the explicit boolean type conversions with double
negations that helps to work JerryScript well with custom boolean types.

(Note: this patch fixes 14 tests on TizenRT.)

[akosthekiss]

@rtakacs What is the compilation error message on TizenRT? What type of x can cause (bool) x to fail but !!x to pass??

[zherczeg]

As far as I understand TizenRT has a built-in "bool emulation" layer for whatever reason. In this layer bool is defined as uint8_t, and (bool)(a & b) is the last 8 bit of the result operation. Obviously this is not the same as the logical value of (a & b).

[akosthekiss]

Here, ecma_number_is_zero returns bool and ecma_builtin_number_prototype_helper_round expects bool. I cannot think of any scenario with whatever bool redefinition where !! would be necessary. So, is this necessary?

[rtakacs]

You are right, that's indeed unnecessary change.

[akosthekiss]

@zherczeg Yikes! Thanks for the background.

[rtakacs]

@akosthekiss There is no compilation error message. The explicit conversation has runtime side effect that appears on some tests.

[zherczeg]

(I like != 0 more than !! although not a strict requirement)

Btw the TizenRT implementation:
https://github.com/Samsung/TizenRT/blob/master/os/include/stdbool.h

[galpeter]

lgtm

[akosthekiss]

I kind of tend to agree with @zherczeg. != 0 is something we use throughout the code base, but I cannot recall to have seen !! in JerryScript before. (I'll double check in some minutes.)

[akosthekiss]

• !! is only used in the definitions of JERRY_LIKELY, JERRY_UNLIKELY, and JERRY_STATIC_ASSERT_GLUE; and at a single assertion in jerry_debugger_receive.
• bool.*!= 0 is used 3 times in "real" code, always in scenarios like & CBC_CODE_FLAGS_STRICT_MODE) != 0

I think we should follow the existing pattern (!= 0).

PS: Self revision, however: 3 times is not "throughout the code base".

[LaszloLango]

@akosthekiss !! is used in the current code base in a few place (JERRY_STATIC_ASSERT, JERRY_LiKELY, JERRY_UNLIKELY, etc.). I don't have strong preferences, !! and !=0 are both good to me, although !! is shorter so it is a bit better to my eyes.

[rtakacs]

@LaszloLango @akosthekiss @zherczeg Thank you for your opinion. I've changed !! to != 0.

[zherczeg]

LGTM

[galpeter]

still lgtm ;)

[LaszloLango]

LGTM

[akosthekiss]

LGTM