Remove almost all special casing for ccache

Apparently we don't need this anymore?  Perhaps because of our CROSSTOOL
specifying absolute paths, perhaps because action_env=PATH is the default
now.  For unsupported_crosstool, we can use an action_env setting to nerf
ccache entirely.

drake/doc/bazel.rst

@@ -29,9 +29,6 @@ The one-time platform setup is the same as for a CMake build:
  - Continue with the *"Mandatory platform specific instructions"* on the same
    page.
 
-When using Bazel, be sure that **ccache is not on your default $PATH**, e.g.,
-``env | grep ccache`` is empty.
-
 .. _using_bazel:
 
 Developing Drake using Bazel
@@ -230,12 +227,3 @@ view it, browse to ``drake-distro/bazel-kcov/index.html``.
    :hidden:
 
    building_kcov
-
-FAQ
-===
-
-Q: What does ``ccache: error: Could not find compiler "gcc" in PATH`` mean?
-
-   A: Your ``$PATH`` still has the magic ``ccache`` directory on it somewhere.
-      Update your dotfiles so that something like ``/usr/lib/ccache`` is not on
-      your ``$PATH``.

drake/doc/clion.rst

@@ -157,10 +157,7 @@ with the environment you actually want!
 
 **Ubuntu users** will generally get good behavior by default, because ``apt``
 installs binaries in reasonable, standard paths, and because most CLion launch
-mechanisms will have already sourced the ``.bashrc``. Do be careful that
-``ccache`` is not on your ``PATH``, though.  If you launch CLion with ``ccache``
-on your ``PATH``, and then CLion launches a Bazel server, you'll need to quit
-CLion, kill the Bazel server, and run ``bazel clean`` to recover.
+mechanisms will have already sourced the ``.bashrc``.
 
 **OS X users** will get broken behavior by default.  When you run an OS X app
 graphically, the parent process is `launchd` (PID 1), which provides its own

setup/ubuntu/16.04/install_prereqs.sh

@@ -60,11 +60,9 @@ fi
 apt update -y
 apt install --no-install-recommends $(tr '\n' ' ' <<EOF
 
-alien
 bash-completion
 binutils
 doxygen
-fakeroot
 g++
 g++-5
 g++-5-multilib
@@ -121,10 +119,10 @@ fi
 
 rm /tmp/bazel_0.5.2-linux-x86_64.deb
 
-# Repair a bad Bazel/ccache interaction.
-# See https://github.com/RobotLocomotion/drake/issues/4464.
-# See https://github.com/bazelbuild/bazel/issues/1322.
-$(dirname $0)/ccache-bazel-wrapper-mkdeb.sh --install
+# Remove deb that we used to generate and install, but no longer need.
+if [ -L /usr/lib/ccache/bazel ]; then
+  apt purge ccache-bazel-wrapper
+fi
 
 # TODO(david-german-tri): Do we need to munge the MATLAB C++ libraries?
 # http://drake.mit.edu/ubuntu.html#matlab

tools/BUILD

@@ -207,20 +207,6 @@ cc_toolchain_suite(
     },
 )
 
-sh_binary(
-    name = "complain_about_ccache",
-    srcs = ["complain_about_ccache.sh"],
-    visibility = ["//visibility:private"],
-)
-
-load("//tools:ccache.bzl", "ccache_is_bad")
-
-# This rule will fail loudly if ccache is on the path.
-ccache_is_bad(
-    name = "ccache_is_bad",
-    visibility = ["//visibility:private"],
-)
-
 filegroup(
     name = "empty",
     srcs = [],
@@ -229,10 +215,10 @@ filegroup(
 
 # This filegroup contains the files on which every toolchain component should
 # always depend, regardless of platform. It is a useful place for the outputs
-# of rules that check preconditions for the entire build.
+# of rules that check preconditions for the entire build.  (At the moment, we
+# do not have any such files, although we once did.)
 filegroup(
     name = "universal_toolchain_deps",
-    srcs = ["ccache.txt"],  # ccache.txt is an output of :ccache_is_bad
     visibility = ["//visibility:private"],
 )
 

tools/bazel.rc

@@ -71,6 +71,7 @@ build:everything --define=WITH_SNOPT=ON
 # Use the default Bazel-generated CROSSTOOL.
 # This may be useful for developers with unsupported workstation configurations.
 build:unsupported_crosstool --crosstool_top=//external:cc_toolchain
+build:unsupported_crosstool --action_env=CCACHE_DISABLE=1
 
 ### git submodules
 # If a CMake build is performed from the same source tree, it will checkout git

tools/ipopt_build_with_autotools.sh

@@ -28,6 +28,11 @@ configure="$PWD"/external/ipopt/configure
 # totally bog down the machine, while still achieving some parallelism.
 half_the_cores="$[($(getconf _NPROCESSORS_ONLN)+1)/2]"
 
+# Within the Bazel sandbox, ccache does not work, so we should turn it off.
+# (The IPOPT build sniffs the path to find a compiler; it neither knows about
+# nor obeys the Bazel --compiler flag.)
+export CCACHE_DISABLE=1
+
 # Set these to match --with-pic below.
 export ADD_CFLAGS=-fPIC
 export ADD_CXXFLAGS=-fPIC