Fix accessing the name of a nested struct definition

src/compiler/translator/ParseContext.cpp

@@ -3896,10 +3896,19 @@ void TParseContext::checkIsBelowStructNestingLimit(const TSourceLoc &line, const
     // one to the field's struct nesting.
     if (1 + field.type()->getDeepestStructNesting() > kWebGLMaxStructNesting)
     {
-        ASSERT(field.type()->getStruct()->name() != nullptr);
         std::stringstream reasonStream;
-        reasonStream << "Reference of struct type " << field.type()->getStruct()->name()->c_str()
-                     << " exceeds maximum allowed nesting level of " << kWebGLMaxStructNesting;
+        if (field.type()->getStruct()->symbolType() == SymbolType::Empty)
+        {
+            // This may happen in case there are nested struct definitions. While they are also
+            // invalid GLSL, they don't cause a syntax error.
+            reasonStream << "Struct nesting";
+        }
+        else
+        {
+            reasonStream << "Reference of struct type "
+                         << field.type()->getStruct()->name()->c_str();
+        }
+        reasonStream << " exceeds maximum allowed nesting level of " << kWebGLMaxStructNesting;
         std::string reason = reasonStream.str();
         error(line, reason.c_str(), field.name().c_str());
         return;

src/tests/compiler_tests/ShaderValidation_test.cpp

@@ -5620,3 +5620,42 @@ TEST_F(FragmentShaderValidationTest,
         FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
     }
 }
+
+// Test going past the struct nesting limit while simultaneously using invalid nested struct
+// definitions. This makes sure that the code generating an error message about going past the
+// struct nesting limit does not access the name of a nameless struct definition.
+TEST_F(WebGL1FragmentShaderValidationTest, StructNestingLimitWithNestedStructDefinitions)
+{
+    const std::string &shaderString =
+        R"(
+        precision mediump float;
+
+        struct
+        {
+            struct
+            {
+                struct
+                {
+                    struct
+                    {
+                        struct
+                        {
+                            struct
+                            {
+                                float f;
+                            } s5;
+                        } s4;
+                    } s3;
+                } s2;
+            } s1;
+        } s0;
+
+        void main(void)
+        {
+            gl_FragColor = vec4(s0.s1.s2.s3.s4.s5.f);
+        })";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
+    }
+}