Don't accept default precision for uint

src/compiler/translator/SymbolTable.h

@@ -435,6 +435,8 @@ class TSymbolTable : angle::NonCopyable
     {
         if (!SupportsPrecision(type.type))
             return false;
+        if (type.type == EbtUInt)
+            return false;  // ESSL 3.00.4 section 4.5.4
         if (type.isAggregate())
             return false; // Not allowed to set for aggregate types
         int indexOfLastElement = static_cast<int>(precisionStack.size()) - 1;

src/tests/compiler_tests/MalformedShader_test.cpp

@@ -1315,3 +1315,22 @@ TEST_F(MalformedShaderTest, TextureLodOffsetOutOfRange)
         FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
     }
 }
+
+// Test that default precision qualifier for uint is not accepted.
+// ESSL 3.00.4 section 4.5.4: Only allowed for float, int and sampler types.
+TEST_F(MalformedShaderTest, DefaultPrecisionUint)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "precision mediump uint;\n"
+        "out vec4 my_FragColor;\n"
+        "void main()\n"
+        "{\n"
+        "   my_FragColor = vec4(0.0);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}

src/tests/compiler_tests/TypeTracking_test.cpp

@@ -297,7 +297,7 @@ TEST_F(TypeTrackingTest, PackResultTypeAndPrecision)
     const std::string &shaderString =
         "#version 300 es\n"
         "precision mediump float;\n"
-        "precision mediump uint;\n"
+        "precision mediump int;\n"
         "uniform vec2 uv;\n"
         "out vec4 my_FragColor;\n"
         "void main() {\n"
@@ -323,7 +323,7 @@ TEST_F(TypeTrackingTest, UnpackNormResultTypeAndPrecision)
     const std::string &shaderString =
         "#version 300 es\n"
         "precision mediump float;\n"
-        "precision mediump uint;\n"
+        "precision mediump int;\n"
         "uniform uint uu;\n"
         "out vec4 my_FragColor;\n"
         "void main() {\n"
@@ -347,7 +347,7 @@ TEST_F(TypeTrackingTest, UnpackHalfResultTypeAndPrecision)
     const std::string &shaderString =
         "#version 300 es\n"
         "precision highp float;\n"
-        "precision highp uint;\n"
+        "precision highp int;\n"
         "uniform uint uu;\n"
         "out vec4 my_FragColor;\n"
         "void main() {\n"