Support default_toolchain override in mbed_app.json

[cyliangtw]

@sg-

Description

On-line IDE compiler will build the code by the default_toolchain in target.json.
For some purpose, some application will prefer to use another one in supported_toolchains.
So, to override the default tool chain by mbed_app.josn is a better way.

Status

READY

Migrations

This PR is to add one more item default_toolchain in CUMULATIVE_ATTRIBUTES.
Also to modify config python file for non-list type of overrides.

Steps to test or reproduce

1. Prepare mbed_app.json like as:

    "target_overrides": {
        "*": {
            "target.default_toolchain": "uARM",
            "platform.stdio-flush-at-exit": false
        }

2. $ mbed compile -m NUMAKER_PFM_NUC472
3. Got debug log as:

Before: ConfigCumulativeOverride: update_target default_toolchain --> Attr: ARM
After: ConfigCumulativeOverride: update_target default_toolchain --> Attr: uARM

[theotherjimmy]

@cyliangtw This seems to confuse the issue of being able to override something with having a cumulative override. You do not have to have a cumulative override to override an attribute.

[sg-]

@theotherjimmy what is the suggested patch? In the online IDE I tried to apply the following to mbed_app.json:

{
    "target_overrides": {
        "*": {
            "target.default_toolchain": "uARM",
            "platform.stdio-flush-at-exit": false
        }
    }
}

and got

Error: Attempt to override undefined parameter 'target.default_toolchain' in 'application[*]'

[theotherjimmy]

diff --git a/tools/config/__init__.py b/tools/config/__init__.py
index 3f265f05a..76b2b92d6 100644
--- a/tools/config/__init__.py
+++ b/tools/config/__init__.py
@@ -642,6 +642,9 @@ class Config(object):
                     if full_name in params:
                         params[full_name].set_value(val, unit_name, unit_kind,
                                                     label)
+                    elif name.startswith("target.") and unit_kind is "application":
+                        _, attribute = name.split(".")
+                        self.target.setattr(attribute, val)
                     elif name in self.__unused_overrides:
                         pass
                     else:

[theotherjimmy]

That [patch ^] would get you the flexibility to override GCC_ARM's default_lib too.

[theotherjimmy]

@sg- I don't think I was trying to say that it would currently work, just that calling an attribute which does not support adds and removes cumulative is going to be confusing to someone eons (months) from now.

[cyliangtw]

Thanks of theotherjimmy mentioned patch, it seems not work at self.target.setattr(), after revise as below, it could work well to override default_toolchain by mbed_app.json.

                    elif name.startswith("target.") and unit_kind is "application":
                        _, attribute = name.split(".")
                        setattr(self.target, attribute, val)                                             

When will you apply this patch into mbed master ?

[adbridge]

@theotherjimmy What needs to happen with this ?

[theotherjimmy]

@cyliangtw Whoops, wrong patch. It should be:

diff --git a/tools/config/__init__.py b/tools/config/__init__.py
index 3f265f05a..76b2b92d6 100644
--- a/tools/config/__init__.py
+++ b/tools/config/__init__.py
@@ -642,6 +642,9 @@ class Config(object):
                     if full_name in params:
                         params[full_name].set_value(val, unit_name, unit_kind,
                                                     label)
+                    elif name.startswith("target.") and unit_kind is "application":
+                        _, attribute = name.split(".")
+                        setattr(self.target, attribute, val)
                     elif name in self.__unused_overrides:
                         pass
                     else:

[theotherjimmy]

@adbridge I would like to see overwriting non-cumulative overrides untangled from the ConfigCumulativeOverride class

[theotherjimmy]

@cyliangtw I think that we could apply that to master soon. There is a big catch though: even though you can override the target.default_toolchain feild, you still won't get the behavior that you want: that the smaller libraries are linked. We would need to add some support code in the online compiler and in the tools to ensure that the right flags get picked up from the build profile.

[cyliangtw]

@theotherjimmy Your patch could work well on off-line compiler by CI command. After finish the support code in the online compiler or arrange the plan schedule, please notify me to evaluate. Thanks a lot.