Fix symbol rendering under opaque fill layers (mapbox#7612)

src/render/draw_symbol.js

@@ -68,9 +68,7 @@ function drawLayerSymbols(painter, sourceCache, layer, coords, isText, translate
     // Unpitched point labels need to have their rotation applied after projection
     const rotateInShader = rotateWithMap && !pitchWithMap && !alongLine;
 
-    const depthOn = pitchWithMap;
-
-    const depthMode = depthOn ? painter.depthModeForSublayer(0, DepthMode.ReadOnly) : DepthMode.disabled;
+    const depthMode = painter.depthModeForSublayer(0, DepthMode.ReadOnly);
 
     let program;
     let size;

src/render/painter.js

@@ -219,9 +219,8 @@ class Painter {
     }
 
     depthModeForSublayer(n, mask, func) {
-        const farDepth = 1 - ((1 + this.currentLayer) * this.numSublayers + n) * this.depthEpsilon;
-        const nearDepth = farDepth - 1 + this.depthRange;
-        return new DepthMode(func || this.context.gl.LEQUAL, mask, [nearDepth, farDepth]);
+        const depth = 1 - ((1 + this.currentLayer) * this.numSublayers + n) * this.depthEpsilon;
+        return new DepthMode(func || this.context.gl.LEQUAL, mask, [depth, depth]);
     }
 
     render(style, options) {

test/integration/render-tests/fill-opacity/opaque-fill-over-symbol-layer/style.json

@@ -0,0 +1,78 @@
+{
+  "version": 8,
+  "metadata": {
+    "test": {
+      "width": 64,
+      "height": 64
+    }
+  },
+  "sources": {
+    "geojson": {
+      "type": "geojson",
+      "data": {
+        "type": "Polygon",
+        "coordinates": [
+          [
+            [
+              -20,
+              -20
+            ],
+            [
+              -20,
+              20
+            ],
+            [
+              20,
+              20
+            ],
+            [
+              20,
+              -20
+            ],
+            [
+              -20,
+              -20
+            ]
+          ]
+        ]
+      }
+    },
+    "icon-source": {
+        "type": "geojson",
+        "data": {
+            "type": "FeatureCollection",
+            "features": [
+                {
+                    "type": "Feature",
+                    "geometry": {
+                        "type": "Point",
+                        "coordinates": [
+                            0,
+                            0
+                        ]
+                    },
+                    "properties": {
+                        "icon": "building"
+                    }
+                }
+            ]
+        }
+    }
+  },
+  "sprite": "local://sprites/sprite",
+  "layers": [
+    {
+        "id": "icons",
+        "type": "symbol",
+        "source": "icon-source",
+        "layout": {
+            "icon-image": "{icon}-12"
+        }
+    },
+    {
+      "id": "fill",
+      "type": "fill",
+      "source": "geojson"
+    }
+  ]
+}