[fasta] Create a 'constant helper' class which will throw on illegal 'constant' expressions

[fasta] Create a 'constant helper' class which will throw on illegal 'constant' expressions

Currently kernel fails a number of test because too much is allowed to be constant.

Examples includes

const x = "hello " * 4; // yielding "hello hello hello hello "
const y = "hello".leng; // crashing the VM

The idea behing the helper class is, that fasta can generate those as for instance
var c = new _ConstantHelper();
const x = c.times("hello ", 4, () => thow yadayada);

where - upon evaluating it in for instance the VMs constant evaluator - the helper will see that "hello " is neiher an integer nor null, and thus execute the given onError function.

This is only one step towards that; it will still have to be hooked up in fasta,
and constant evaluators (e.g. in the VM, I suppose there's also one in dart2js etc)
might need to be updated to be able to execute it.

R=ahe@google.com

Committed: https://github.com/dart-lang/sdk/commit/73a54a30d566cb5eaa0b0e1ed12f3b770c91c97f

[jensj, 2017-07-14 13:30:53]

Description was changed from

==========
[fasta] Create a 'constant helper' class which will throw on illegal 'constant'
expressions

Currently kernel fails a number of test because too much is allowed to be
constant.
Examples includes
const x = "hello " * 4;
const y = "hello".leng;

The idea behing the helper class is, that fasta can generate those as for
instance
var c = new _ConstantHelper();
const x = c.times("hello ", 4, () => thow yadayada);

where - upon evaluating it in for instance the VMs constant evaluator - the
helper will see
that "hello " is neiher an integer nor null, and thus execute the given onError
function.

This is only one step towards that; it will still have to be hooked up in fasta,
and constant evaluators (e.g. in the VM, I suppose there's also one in dart2js
etc)
might need to be updated to be able to execute it.
==========

to

==========
[fasta] Create a 'constant helper' class which will throw on illegal 'constant'
expressions

Currently kernel fails a number of test because too much is allowed to be
constant.

Examples includes

const x = "hello " * 4; // yielding "hello hello hello hello "
const y = "hello".leng; // crashing the VM

The idea behing the helper class is, that fasta can generate those as for
instance
var c = new _ConstantHelper();
const x = c.times("hello ", 4, () => thow yadayada);

where - upon evaluating it in for instance the VMs constant evaluator - the
helper will see that "hello " is neiher an integer nor null, and thus execute
the given onError function.

This is only one step towards that; it will still have to be hooked up in fasta,
and constant evaluators (e.g. in the VM, I suppose there's also one in dart2js
etc)
might need to be updated to be able to execute it.
==========

[jensj, 2017-07-14 13:30:53]

jensj@google.com changed reviewers:
+ ahe@google.com, kmillikin@google.com

[jensj, 2017-07-14 13:34:39]

Based on idea from Peter. PTAL.

(It should be noted that I'm going on vacation in a few minutes so even if
approved I'm probably not going to land anything anytime soon.)

Also, in the long run this should probably be replaced by something else.

[ahe, 2017-07-14 13:46:36]

LGTM, this should be safe to land before going on vacation.

[jensj, 2017-08-03 06:38:35]

Description was changed from

==========
[fasta] Create a 'constant helper' class which will throw on illegal 'constant'
expressions

Currently kernel fails a number of test because too much is allowed to be
constant.

Examples includes

const x = "hello " * 4; // yielding "hello hello hello hello "
const y = "hello".leng; // crashing the VM

The idea behing the helper class is, that fasta can generate those as for
instance
var c = new _ConstantHelper();
const x = c.times("hello ", 4, () => thow yadayada);

where - upon evaluating it in for instance the VMs constant evaluator - the
helper will see that "hello " is neiher an integer nor null, and thus execute
the given onError function.

This is only one step towards that; it will still have to be hooked up in fasta,
and constant evaluators (e.g. in the VM, I suppose there's also one in dart2js
etc)
might need to be updated to be able to execute it.
==========

to

==========
[fasta] Create a 'constant helper' class which will throw on illegal 'constant'
expressions

Currently kernel fails a number of test because too much is allowed to be
constant.

Examples includes

const x = "hello " * 4; // yielding "hello hello hello hello "
const y = "hello".leng; // crashing the VM

The idea behing the helper class is, that fasta can generate those as for
instance
var c = new _ConstantHelper();
const x = c.times("hello ", 4, () => thow yadayada);

where - upon evaluating it in for instance the VMs constant evaluator - the
helper will see that "hello " is neiher an integer nor null, and thus execute
the given onError function.

This is only one step towards that; it will still have to be hooked up in fasta,
and constant evaluators (e.g. in the VM, I suppose there's also one in dart2js
etc)
might need to be updated to be able to execute it.

R=ahe@google.com

Committed:
https://github.com/dart-lang/sdk/commit/73a54a30d566cb5eaa0b0e1ed12f3b770c91c97f
==========

[jensj, 2017-08-03 06:38:36]

Committed patchset #1 (id:1) manually as
73a54a30d566cb5eaa0b0e1ed12f3b770c91c97f (presubmit successful).

[jensj, 2017-08-03 06:49:56]

On 2017/07/14 13:46:36, ahe wrote:
> LGTM, this should be safe to land before going on vacation.

Landed now. I had already left when you wrote the above :)