refactor(travis): Add minimal build configuration

Uses none of the optional dependencies. This ensures that polybar can
build without any of the supposedly optional dependencies. This would
have detected the cause of the xrm build failure before it was merged

.travis.yml

@@ -69,6 +69,12 @@ matrix:
       env: BUILD_TYPE=Debug
       addons: {apt: {sources: *sources, packages: [*gcc, *base_deps, *optional_deps]}}
 
+      # Minimal build, contains no optional dependencies. This makes sure that
+      # we properly remove files from compilation that depend on libraries that
+      # are not installed
+    - compiler: gcc
+      env: BUILD_TYPE=Release POLYBAR_BUILD_TYPE=minimal
+      addons: {apt: {sources: *sources, packages: [*gcc, *base_deps]}}
 
 cache:
   ccache: true

common/travis/configure.sh

@@ -1,9 +1,32 @@
 #!/bin/bash
 mkdir -p "${TRAVIS_BUILD_DIR}/build"
 cd "${TRAVIS_BUILD_DIR}/build" || false
+
+FLAGS=""
+
+# Disable all extra modules and X extensions for minimal builds
+# Most of these should already be turned off because their libraries are not
+# installed, but some may not be
+if [ "$POLYBAR_BUILD_TYPE" == "minimal" ]; then
+  FLAGS=(
+  "-DENABLE_PULSEAUDIO=OFF"
+  "-DENABLE_NETWORK=OFF"
+  "-DENABLE_MPD=OFF"
+  "-DENABLE_CURL=OFF"
+  "-DENABLE_ALSA=OFF"
+  "-DENABLE_I3=OFF"
+  "-DWITH_XRM=OFF"
+  "-DWITH_XKB=OFF"
+  "-DWITH_XRANDR_MONITORS=OFF"
+  "-DWITH_XCURSOR=OFF"
+  "-DWITH_XRANDR=ON"
+  )
+fi
+
 cmake \
   -DCMAKE_C_COMPILER="${CC}" \
   -DCMAKE_CXX_COMPILER="${CXX}" \
   -DCMAKE_CXX_FLAGS="${CXXFLAGS}" \
   -DCMAKE_BUILD_TYPE="${BUILD_TYPE}" \
-  -DBUILD_TESTS:BOOL="${BUILD_TESTS:-OFF}" ..
+  -DBUILD_TESTS:BOOL="${BUILD_TESTS:-OFF}" \
+  "${FLAGS[@]}" ..

common/travis/install_xcb_xrm.sh

@@ -1,5 +1,11 @@
 #!/bin/bash
 
+# Don't install xrm on minimal builds because it is an optional dependency
+if [ "$POLYBAR_BUILD_TYPE" == "minimal" ]; then
+  echo "Not installing xcb-xrm on minimal build"
+  return 0
+fi
+
 # Fail on error
 set -e