QOpenGLShader::compile errors

Setup:

• Qt3D/QML Scene3D in QQuickWidget
• Scenegraph (but not the framegraph) is being manipulated from C++
• Notable used Qt3D objects: QPerVertexColorMaterial, QPhongAlphaMaterial, QPlaneMesh, QMesh,  QTextureMaterial, QExtrudedTextMesh, QPaintedTextureImage
• MSVC 2019 x64

At the start of the application, the following error is reported via application output:

QOpenGLShaderPrivate::compile: QOpenGLShader::compile(Fragment): ERROR: 4:2: 'add' : syntax error syntax error

QOpenGLShaderPrivate::compile: *** Problematic Fragment shader source code ***
#version 110
#ifdef GL_KHR_blend_equation_advanced
#extension GL_ARB_fragment_coord_conventions : enable
#extension GL_KHR_blend_equation_advanced : enable
#endif
#define lowp
#define mediump
#define highp
#line 1

add-input varying vec3 worldPosition
add-input varying vec3 worldNormal
add-input uniform vec4 ka
add-input uniform vec4 kd
add-input uniform vec4 ks
add-input uniform float shininess
/****************************************************************************
**

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  • Alternatively, you may use this file under the terms of the BSD license
  • as follows:
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  • modification, are permitted provided that the following conditions are
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  • * Redistributions of source code must retain the above copyright
  • notice, this list of conditions and the following disclaimer.
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layout(std140, binding = auto) uniform qt3d_render_view_uniforms

;

layout(std140, binding = auto) uniform qt3d_command_uniforms

;

layout(std140, binding = auto) uniform qt3d_extras_uniforms

;

#line 2

const int MAX_LIGHTS = 8;
const int TYPE_POINT = 0;
const int TYPE_DIRECTIONAL = 1;
const int TYPE_SPOT = 2;

struct Light

;

layout(std140, binding = auto) uniform qt3d_light_uniforms

;

// Pre-convolved environment maps
layout(binding = auto) uniform samplerCube envLight_irradiance; // For diffuse contribution
layout(binding = auto) uniform samplerCube envLight_specular; // For specular contribution

#line 52

void adsModel(const in vec3 worldPos,
const in vec3 worldNormal,
const in vec3 worldView,
const in float shininess,
out vec3 diffuseColor,
out vec3 specularColor)
{
diffuseColor = vec3(0.0);
specularColor = vec3(0.0);

// We perform all work in world space
vec3 n = normalize(worldNormal);
vec3 s = vec3(0.0);

for (int i = 0; i < lightCount; ++i) {
float att = 1.0;
float sDotN = 0.0;

if (lights[i].type != TYPE_DIRECTIONAL) {
// Point and Spot lights

// Light position is already in world space
vec3 sUnnormalized = lights[i].position - worldPos;
s = normalize(sUnnormalized); // Light direction

// Calculate the attenuation factor
sDotN = dot(s, n);
if (sDotN > 0.0) {
if (lights[i].constantAttenuation != 0.0

// The light direction is in world space already
if (lights[i].type == TYPE_SPOT)

}
} else

// Calculate the diffuse factor
float diffuse = max(sDotN, 0.0);

// Calculate the specular factor
float specular = 0.0;
if (diffuse > 0.0 && shininess > 0.0)

// Accumulate the diffuse and specular contributions
diffuseColor += att * lights[i].intensity * diffuse * lights[i].color;
specularColor += att * lights[i].intensity * specular * lights[i].color;
}
}

vec4 phongFunction(const in vec4 ambient,
const in vec4 diffuse,
const in vec4 specular,
const in float shininess,
const in vec3 worldPosition,
const in vec3 worldView,
const in vec3 worldNormal)

#line 10
layout(location = 0) out vec4 fragColor;

void main()

***

Additionally, the 3D view is blank until the camera is moved. Then the view appears and everything seems to be as it should be.

None of this is present when compiled with Qt 5.14.2.