error: invalid operands to binary expression ('drake::symbolic::Expression' and 'drake::symbolic::Expression')

[tarquasso]

./drake/examples/DoublePendulum/gen/double_pendulum_state_vector.h:81:16: error: invalid operands to binary expression ('drake::symbolic::Expression' and 'drake::symbolic::Expression')
  decltype(T() < T()) IsValid() const 

Having troubles compiling a new plant using the auto-generated state vector file:
gen/double_pendulum_state_vector.h file (It was generated with: double_pendulum_gen.sh)

A comparision T() < T() fails for two drake::symbolic::Expression.

The example is called "DoublePendulum", a duplicate of Acrobot example, but fully actuated. See the other source files here: Github DoublePendulum Example (branched of master sha b6a35cece18a34f06ece2fdc24b15096a474ee9a as of 8/11/17 10am)

Here the full compiler error message:

ERROR: /home/rkk/drake-distro/drake/examples/DoublePendulum/BUILD:64:1: C++ compilation of rule '//drake/examples/DoublePendulum:double_pendulum_plant' failed: Process exited with status 1 [sandboxed].
In file included from drake/examples/DoublePendulum/double_pendulum_plant.cc:1:
In file included from ./drake/examples/DoublePendulum/double_pendulum_plant.h:5:
./drake/examples/DoublePendulum/gen/double_pendulum_state_vector.h:81:16: error: invalid operands to binary expression ('drake::symbolic::Expression' and 'drake::symbolic::Expression')
  decltype(T() < T()) IsValid() const {
           ~~~ ^ ~~~
drake/examples/DoublePendulum/double_pendulum_plant.cc:40:33: note: in instantiation of template class 'drake::examples::double_pendulum::DoublePendulumStateVector<drake::symbolic::Expression>' requested here
  this->DeclareVectorOutputPort(DoublePendulumStateVector<T>());
                                ^
drake/examples/DoublePendulum/double_pendulum_plant.cc:160:14: note: in instantiation of member function 'drake::examples::double_pendulum::DoublePendulumPlant<drake::symbolic::Expression>::DoublePendulumPlant' requested here
  return new DoublePendulumPlant<symbolic::Expression>();
             ^
./drake/common/symbolic_expression.h:63:6: note: candidate function not viable: no known conversion from 'drake::symbolic::Expression' to 'drake::symbolic::ExpressionKind' for 1st argument
bool operator<(ExpressionKind k1, ExpressionKind k2);
     ^
1 error generated.

Any tips on how to understand this / fix it are highly appreciated!

[soonho-tri]

Could you test the following patch?

--- a/drake/examples/DoublePendulum/double_pendulum_plant.h
+++ b/drake/examples/DoublePendulum/double_pendulum_plant.h
@@ -7,6 +7,7 @@
 #include "drake/systems/framework/diagram.h"
 #include "drake/systems/framework/leaf_system.h"
 #include "drake/systems/primitives/affine_system.h"
+#include "drake/common/symbolic_formula.h"

[soonho-tri]

I think a better solution is to rebase your branch against the latest master branch of RobotLocomotion/drake repository and to include the following in double_pendulum_plant.h if needed:

#include "drake/common/symbolic.h"

[tarquasso]

I performed the rebase to current master, now I can't build anymore:

~/drake-distro/drake/examples/DoublePendulum$ bazel build ...
ERROR: /home/rkk/.cache/bazel/_bazel_rkk/cc1738dde3d5a7f5de70cb525c89ee8a/external/drake/tools/install.bzl:278:9: name 'DefaultInfo' is not defined.
ERROR: error loading package 'tools': Extension 'tools/install.bzl' has errors.
INFO: Elapsed time: 0.305s

and my externals folder is filled with nested roots:

git status
On branch double_pendulum
Your branch is up-to-date with 'origin/double_pendulum'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   externals/bullet (new commits)

Untracked files:
  (use "git add <file>..." to include in what will be committed)

    drake/examples/LittleDog/
    externals/avl/
    externals/ccd/
    externals/fcl/
    externals/gurobi/
    externals/iris/
    externals/meshconverters/
    externals/mosek/
    externals/octomap/
    externals/sedumi/
    externals/signalscope/
    externals/snopt/
    externals/spotless/
    externals/vtk/
    externals/xfoil/
    externals/yalmip/

Shall I clean my workspace according to: Clean Workspace Instruction for make or is there a better way since I am using bazel?

[jwnimmer-tri]

There is a bazel clean command, but I don't think that's your problem. In http://drake.mit.edu/developers.html, the Bazel version we use is 0.5.2 (and I believe 0.5.3 also works); is that what you're trying to use?

[tarquasso]

updating bazel and rebasing from master fixed the issue.