Why operator 'pass' not implement to 'if-else' linear expression?
Construction '<func/operation> if <expression> else pass' throws SyntaxError in Python 3.9

This is not a bug, "pass" is not an operator, it is not an expression, it is a statement and is only allowed in places where statements are allowed.

The if expression requires all three operands to be expressions.

Even if "pass" was permitted, what would it do? What would be the value of x after this assignment?

    x = 1 if False else pass

If you need x to be undefined, use an if statement:


    if False:
        # this block is not run
        x = 1

    # x is undefined here

ok, but what you say for this?

x += x*2 if math.pow(x) > 386 else pass

and 

if math.pow(x) > 386:
 x += x*2

1 line vs 2 line

now i'm use this

x += x*2 if math.pow(x) > 386 else ''

it is more readable

or another example:

def my_func(x):
 something_do....


my_func(x) if x > 100 else <no call this function>

this wrong example

now i'm use this
x += x*2 if math.pow(x) > 386 else ''

wanted to say that doing this now

my_func(x) if x > 100 else ''

formaly it's not bug, this is future request ok?

Well,
x = 1 if False else pass
and
if False: x = 1

1 line vs 1 line :) It's just not needed.

If you want pass to become an expression, what should these do?

    x = pass

    print(pass)

    mydict[pass] = 1

    type(pass)

There is nothing special about the ternary if operator. It is just an 
operator like plus, minus and more. The only difference is that plus 
takes two arguments, and if...else takes three:

    expression + expression

    expression if expression else expression

If pass becomes legal in the if...else ternary operatory, it must be an 
expression, so it must have a value. What is that value?

What about this?

if x > 2: my_func(x)

ok this code at 1 line, this code work, but...

PEP 8: E701 multiple statements on one line (colon)


Well f//k it with a pass
Why not add an empty action operator? What is the problem? Such an instruction has existed since the days of assembler - nop

Evgeniy, please leave this closed and take the proposal to the python-ideas mailing list.   There is no further progress that can be made in this tracker issue.  We can’t discern any part of your proposal that would make sense for improving the language.