Add getTarget method to CompilerCommandLine

Add getTarget method to CompilerCommandLine

The method is used to create an instance of a backend target class.
CompilerCommandLine already has the necessary information for this ("target"
name string and "strongMode" flag).  Additionally, a backed target instance is
now not created in fasta.dart/parseScriptInFileSystem, but should be passed at
the call site.

R=ahe@google.com, scheglov@google.com

Committed: https://github.com/dart-lang/sdk/commit/aa8ca9244a3cc5fa7c3816a9340558e7d2f37ae1

[Dmitry Stefantsov, 2017-06-08 13:27:56]

dmitryas@google.com changed reviewers:
+ ahe@google.com, scheglov@google.com

[ahe, 2017-06-08 14:49:37]

LGTM with comments!

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
File pkg/front_end/lib/src/fasta/compiler_command_line.dart (right):

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:66: }
Suggestion:

backend_targets.Target target = backend_targets.getTarget(
    targetName, new backend_targets.TargetFlags(strongMode: strongMode));
if (target == null) {
  return argumentError(usage, "Target '${targetName} not recognized. Valid
targets are:\n  ${backend_targets.targets.join("\n  ")}");
}
options["target"] = target;

And then below:

backend_targets.Target get target => options["target"];

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:97: String get target {
Rename this to targetName.

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:101:
backend_targets.Target getTarget() {
Change this to:

backend_targets.Target get target {

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:105: return cachedTarget
= backend_targets.getTarget(
Use ??=

[scheglov, 2017-06-08 18:47:24]

lgtm

[Dmitry Stefantsov, 2017-06-09 08:24:40]

Thanks for the comments, Peter! I agree with them and applied the changes.

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
File pkg/front_end/lib/src/fasta/compiler_command_line.dart (right):

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:66: }
On 2017/06/08 14:49:37, ahe wrote:
> Suggestion:
> 
> backend_targets.Target target = backend_targets.getTarget(
>     targetName, new backend_targets.TargetFlags(strongMode: strongMode));
> if (target == null) {
>   return argumentError(usage, "Target '${targetName} not recognized. Valid
> targets are:\n  ${backend_targets.targets.join("\n  ")}");
> }
> options["target"] = target;
> 
> And then below:
> 
> backend_targets.Target get target => options["target"];

Thanks for the suggestion! I agree. This way we may show the error message at
the appropriate time. Done.

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:97: String get target {
On 2017/06/08 14:49:37, ahe wrote:
> Rename this to targetName.

Done.

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:101:
backend_targets.Target getTarget() {
On 2017/06/08 14:49:37, ahe wrote:
> Change this to:
> 
> backend_targets.Target get target {

Done.

https://codereview.chromium.org/2932513003/diff/1/pkg/front_end/lib/src/fasta...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:105: return cachedTarget
= backend_targets.getTarget(
On 2017/06/08 14:49:37, ahe wrote:
> Use ??=

Thanks for the suggestion! It looks way better than if-return-than-return.

Also, now that we use eager caching during parameters validation, we don't need
this method body. But I'll keep the trick for when I need to lazily cache
things.

[ahe, 2017-06-09 08:29:18]

lgtm

One small typo below.

https://codereview.chromium.org/2932513003/diff/20001/pkg/front_end/lib/src/f...
File pkg/front_end/lib/src/fasta/compiler_command_line.dart (right):

https://codereview.chromium.org/2932513003/diff/20001/pkg/front_end/lib/src/f...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:72: "Target
'${targetName} not recognized. "
Add single quote after }.

[Dmitry Stefantsov, 2017-06-09 08:37:04]

https://codereview.chromium.org/2932513003/diff/20001/pkg/front_end/lib/src/f...
File pkg/front_end/lib/src/fasta/compiler_command_line.dart (right):

https://codereview.chromium.org/2932513003/diff/20001/pkg/front_end/lib/src/f...
pkg/front_end/lib/src/fasta/compiler_command_line.dart:72: "Target
'${targetName} not recognized. "
On 2017/06/09 08:29:18, ahe wrote:
> Add single quote after }.

Good catch! Thanks! Fixed.

[Dmitry Stefantsov, 2017-06-09 09:04:53]

Description was changed from

==========
Add getTarget method to CompilerCommandLine

The method is used to create an instance of a backend target class.
CompilerCommandLine already has the necessary information for this ("target"
name string and "strongMode" flag).  Additionally, a backed target instance is
now not created in fasta.dart/parseScriptInFileSystem, but should be passed at
the call site.
==========

to

==========
Add getTarget method to CompilerCommandLine

The method is used to create an instance of a backend target class.
CompilerCommandLine already has the necessary information for this ("target"
name string and "strongMode" flag).  Additionally, a backed target instance is
now not created in fasta.dart/parseScriptInFileSystem, but should be passed at
the call site.

R=ahe@google.com, scheglov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/aa8ca9244a3cc5fa7c3816a9340558e7d2f37ae1
==========

[Dmitry Stefantsov, 2017-06-09 09:04:54]

Committed patchset #4 (id:60001) manually as
aa8ca9244a3cc5fa7c3816a9340558e7d2f37ae1 (presubmit successful).