From 2e630297afc19ef4e69b8afe79dfd337171dbd60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Foucault?= <foucault.clem@gmail.com>
Date: Fri, 21 Aug 2020 14:25:58 +0200
Subject: [PATCH] GPUShader: Fix linking working even if one shader compilation
 failed

Linking without valid shaders works on some drivers. Avoid this case by
forcing linking step to return false.
---
 source/blender/gpu/opengl/gl_shader.cc | 5 +++++
 source/blender/gpu/opengl/gl_shader.hh | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/source/blender/gpu/opengl/gl_shader.cc b/source/blender/gpu/opengl/gl_shader.cc
index b2cca2ef45e..3ec818b53a6 100644
--- a/source/blender/gpu/opengl/gl_shader.cc
+++ b/source/blender/gpu/opengl/gl_shader.cc
@@ -151,6 +151,7 @@ GLuint GLShader::create_shader_stage(GLenum gl_stage, MutableSpan<const char *>
   }
   if (!status) {
     glDeleteShader(shader);
+    compilation_failed_ = true;
     return 0;
   }
 
@@ -193,6 +194,10 @@ void GLShader::fragment_shader_from_glsl(MutableSpan<const char *> sources)
 
 bool GLShader::finalize(void)
 {
+  if (compilation_failed_) {
+    return false;
+  }
+
   glLinkProgram(shader_program_);
 
   GLint status;
diff --git a/source/blender/gpu/opengl/gl_shader.hh b/source/blender/gpu/opengl/gl_shader.hh
index 37119b8b093..a686014f4c5 100644
--- a/source/blender/gpu/opengl/gl_shader.hh
+++ b/source/blender/gpu/opengl/gl_shader.hh
@@ -39,10 +39,12 @@ class GLShader : public Shader {
  private:
   /** Handle for full program (links shader stages below). */
   GLuint shader_program_ = 0;
-
+  /** Individual shader stages. */
   GLuint vert_shader_ = 0;
   GLuint geom_shader_ = 0;
   GLuint frag_shader_ = 0;
+  /** True if any shader failed to compile. */
+  bool compilation_failed_ = false;
 
   eGPUShaderTFBType transform_feedback_type_ = GPU_SHADER_TFB_NONE;