Cannot pin version for transitive dependency

[OttoWinter]

What kind of issue is this?

• PlatformIO Core.
  If you’ve found a bug, please provide an information below.

You can erase any parts of this template not applicable to your Issue.

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Configuration

Operating system: macOS (Darwin Kernel Version 18.5.0)

PlatformIO Version (platformio --version): PlatformIO, version 3.6.4

Description of problem

Cannot pin version of dependency when another dependency uses it (general library dependency graph problem, not specific to platform).

I recently tried the [email protected] package, but that turned out to be too unstable in a couple of places. Now I want to go back to [email protected] but am hitting a problem downgrading a dependency.

I'm using the Async MQTT client library which uses the AsyncTCP library. [email protected] is only compatible with [email protected], but [email protected] is only compatible with [email protected] - so I need platformio to pin AsyncTCP to @1.0.1 for using [email protected]

However, since AsyncMQTTClient uses AsyncTCP, I cannot manually pin the version in lib_deps:

lib_deps =
    [email protected]
    [email protected]

results in:

Scanning dependencies...
Dependency Graph
|-- <AsyncMqttClient> 0.8.2
|   |-- <AsyncTCP> 1.0.3
|-- <AsyncTCP> 1.0.1

which fails because AsyncTCP is compiled twice (once with 1.0.3 and once with 1.0.1).
AsyncMqttClient does not pin the AsyncTCP version, so I would expect putting [email protected] would also override the AsyncTCP platformio uses for AsyncMqttClient (like most package managers)

Steps to Reproduce

1. New platformio project, platformio.ini (nothing in src/):

[env:nodemcu-32s]
platform = [email protected]
board = nodemcu-32s
framework = arduino
lib_deps =
    [email protected]
    [email protected]

2. Observe pio run output:

Scanning dependencies...
Dependency Graph
|-- <AsyncMqttClient> 0.8.2
|   |-- <AsyncTCP> 1.0.3
|-- <AsyncTCP> 1.0.1

AsyncTCP appears twice with two versions.

3. When compiling (touch src/main.cpp), it also appears like 1.0.3 is compiled (resulting in compile error)

Actual Results

see above

Expected Results

|-- <AsyncMqttClient> 0.8.2
|   |-- <AsyncTCP> 1.0.1
|-- <AsyncTCP> 1.0.1

(can pin transitive dependencies in lib_deps)

Additional info

[OttoWinter]

Turns out order matters for these entries:

lib_deps =
    [email protected]
    [email protected]

results in

Dependency Graph
|-- <AsyncTCP> 1.0.1
|-- <AsyncMqttClient> 0.8.2
|   |-- <AsyncTCP> 1.0.1

I'm gonna keep this issue open because order shouldn't matter for these things IMO

[ivankravets]

lib_deps =
[email protected]
[email protected]

Could you swap 2 of these lines? Please [email protected] as first.