diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 50bb7b2..37fae64 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -25,9 +25,12 @@
     },
 
     clang: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     cppflags: [
         "-Weverything",
-        "-Werror",
 
         // The static constructors and destructors in this library have not been noted to
         // introduce significant overheads
diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index 7b2b5c3..5bee7a4 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -153,7 +153,10 @@
     ATRACE_CALL();
 
     DisplayStatInfo stats;
-    status_t err = composerService()->getDisplayStats(NULL, &stats);
+    status_t result = composerService()->getDisplayStats(NULL, &stats);
+    if (result != NO_ERROR) {
+        return result;
+    }
 
     *outRefreshDuration = stats.vsyncPeriod;
 
diff --git a/libs/gui/tests/Android.bp b/libs/gui/tests/Android.bp
index fa87f29..908959c 100644
--- a/libs/gui/tests/Android.bp
+++ b/libs/gui/tests/Android.bp
@@ -7,6 +7,10 @@
     test_suites: ["device-tests"],
 
     clang: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 
     srcs: [
         "BufferItemConsumer_test.cpp",
diff --git a/libs/gui/tests/CpuConsumer_test.cpp b/libs/gui/tests/CpuConsumer_test.cpp
index 0982d7e..588e541 100644
--- a/libs/gui/tests/CpuConsumer_test.cpp
+++ b/libs/gui/tests/CpuConsumer_test.cpp
@@ -310,8 +310,6 @@
     uint32_t h = buf.height;
     const int blockWidth = w > 16 ? w / 16 : 1;
     const int blockHeight = h > 16 ? h / 16 : 1;
-    const int blockRows = h / blockHeight;
-    const int blockCols = w / blockWidth;
 
     // Top-left square is bright
     checkPixel(buf, 0, 0, 191);
@@ -349,8 +347,6 @@
     uint32_t h = buf.height;
     const int blockWidth = w > 16 ? w / 16 : 1;
     const int blockHeight = h > 16 ? h / 16 : 1;
-    const int blockRows = h / blockHeight;
-    const int blockCols = w / blockWidth;
 
     // Top-left square is bright red
     checkPixel(buf, 0, 0, 191, 63, 63);
@@ -392,8 +388,6 @@
     uint32_t h = buf.height;
     const int blockWidth = (w > 16 ? w / 8 : 2) & ~0x1;
     const int blockHeight = (h > 16 ? h / 8 : 2) & ~0x1;
-    const int blockRows = h / blockHeight;
-    const int blockCols = w / blockWidth;
 
     // Top-left square is red
     checkPixel(buf, 0, 0, 1000, 200, 200);
diff --git a/libs/gui/tests/SurfaceTextureGL_test.cpp b/libs/gui/tests/SurfaceTextureGL_test.cpp
index c6745d0..5639286 100644
--- a/libs/gui/tests/SurfaceTextureGL_test.cpp
+++ b/libs/gui/tests/SurfaceTextureGL_test.cpp
@@ -323,7 +323,6 @@
         for (int j = 0; j < numTestPixels; j++) {
             int x = testPixels[j].x;
             int y = testPixels[j].y;
-            uint8_t value = 0;
             if (j == (i % numTestPixels)) {
                 // We must y-invert the texture coords
                 EXPECT_TRUE(checkPixel(x, texHeight-y-1, 255, 255, 255, 255));
diff --git a/libs/gui/tests/Surface_test.cpp b/libs/gui/tests/Surface_test.cpp
index e18af17..e572e51 100644
--- a/libs/gui/tests/Surface_test.cpp
+++ b/libs/gui/tests/Surface_test.cpp
@@ -1075,7 +1075,6 @@
     EXPECT_EQ(initialCompositorTiming.presentLatency,
               compositeToPresentLatency);
 
-    const uint64_t fId1 = getNextFrameId();
     dequeueAndQueue(0);
     addFrameEvents(true, NO_FRAME_INDEX, 0);
 
@@ -1089,7 +1088,6 @@
     EXPECT_EQ(initialCompositorTiming.presentLatency,
               compositeToPresentLatency);
 
-    const uint64_t fId2 = getNextFrameId();
     dequeueAndQueue(1);
     addFrameEvents(true, 0, 1);
 
@@ -1162,7 +1160,6 @@
     nsecs_t expectedDeadline = initialCompositorTiming.deadline;
     EXPECT_EQ(expectedDeadline, compositeDeadline);
 
-    const uint64_t fId1 = getNextFrameId();
     dequeueAndQueue(0);
     addFrameEvents(true, NO_FRAME_INDEX, 0);
 
@@ -1175,7 +1172,6 @@
             initialCompositorTiming.deadline +initialCompositorTiming.interval;
     EXPECT_EQ(expectedDeadline, compositeDeadline);
 
-    const uint64_t fId2 = getNextFrameId();
     dequeueAndQueue(1);
     addFrameEvents(true, 0, 1);
 
diff --git a/libs/ui/Android.bp b/libs/ui/Android.bp
index 28b8ab3..14c0d5c 100644
--- a/libs/ui/Android.bp
+++ b/libs/ui/Android.bp
@@ -20,9 +20,12 @@
     },
 
     clang: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
     cppflags: [
         "-Weverything",
-        "-Werror",
 
         // The static constructors and destructors in this library have not been noted to
         // introduce significant overheads
diff --git a/libs/ui/GraphicBufferMapper.cpp b/libs/ui/GraphicBufferMapper.cpp
index 5b0e7f6..d5a30d7 100644
--- a/libs/ui/GraphicBufferMapper.cpp
+++ b/libs/ui/GraphicBufferMapper.cpp
@@ -125,29 +125,6 @@
     return static_cast<status_t>(error);
 }
 
-static inline bool isValidYCbCrPlane(const android_flex_plane_t& plane) {
-    if (plane.bits_per_component != 8) {
-        ALOGV("Invalid number of bits per component: %d",
-                plane.bits_per_component);
-        return false;
-    }
-    if (plane.bits_used != 8) {
-        ALOGV("Invalid number of bits used: %d", plane.bits_used);
-        return false;
-    }
-
-    bool hasValidIncrement = plane.h_increment == 1 ||
-            (plane.component != FLEX_COMPONENT_Y && plane.h_increment == 2);
-    hasValidIncrement = hasValidIncrement && plane.v_increment > 0;
-    if (!hasValidIncrement) {
-        ALOGV("Invalid increment: h %d v %d", plane.h_increment,
-                plane.v_increment);
-        return false;
-    }
-
-    return true;
-}
-
 status_t GraphicBufferMapper::lockAsyncYCbCr(buffer_handle_t handle,
         uint32_t usage, const Rect& bounds, android_ycbcr *ycbcr, int fenceFd)
 {
diff --git a/libs/ui/tests/Android.bp b/libs/ui/tests/Android.bp
index 6733505..08067fc 100644
--- a/libs/ui/tests/Android.bp
+++ b/libs/ui/tests/Android.bp
@@ -18,10 +18,12 @@
     name: "Region_test",
     shared_libs: ["libui"],
     srcs: ["Region_test.cpp"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 cc_test {
     name: "colorspace_test",
     shared_libs: ["libui"],
     srcs: ["colorspace_test.cpp"],
+    cflags: ["-Wall", "-Werror"],
 }