Fix some default return values in auto-gen.

scripts/generate_entry_points.py

@@ -156,17 +156,10 @@ def param_format_string(param):
 
         return param + " = " + format_dict[type_only]
 
-def default_return_value(return_type):
+def default_return_value(cmd_name, return_type):
     if return_type == "void":
         return ""
-    elif return_type == "GLenum" or return_type == "GLint" or return_type == "GLuint":
-        return "0"
-    elif return_type == "GLboolean":
-        return "GL_FALSE"
-    elif "*" in return_type or return_type == "GLsync":
-        return "nullptr"
-    else:
-        raise Exception("Don't know default return type for " + return_type)
+    return "GetDefaultReturnValue<EntryPoint::" + cmd_name[2:] + ", " + return_type + ">()"
 
 def get_context_getter_function(cmd_name):
     if cmd_name == "glGetError":
@@ -178,7 +171,7 @@ def format_entry_point_def(cmd_name, proto, params):
     pass_params = [just_the_name(param) for param in params]
     format_params = [param_format_string(param) for param in params]
     return_type = proto[:-len(cmd_name)]
-    default_return = default_return_value(return_type.strip())
+    default_return = default_return_value(cmd_name, return_type.strip())
     return template_entry_point_def.format(
         name = cmd_name[2:],
         name_lower = cmd_name[2:3].lower() + cmd_name[3:],

src/libANGLE/params.h

@@ -167,6 +167,43 @@ struct EntryPointParam
     using Type = ParamsBase;
 };
 
+// A template struct for determining the default value to return for each entry point.
+template <EntryPoint EP, typename ReturnType>
+struct DefaultReturnValue;
+
+// Default return values for each basic return type.
+template <EntryPoint EP>
+struct DefaultReturnValue<EP, GLint>
+{
+    static constexpr GLint kValue = -1;
+};
+
+// This doubles as the GLenum return value.
+template <EntryPoint EP>
+struct DefaultReturnValue<EP, GLuint>
+{
+    static constexpr GLuint kValue = 0;
+};
+
+template <EntryPoint EP>
+struct DefaultReturnValue<EP, GLboolean>
+{
+    static constexpr GLboolean kValue = GL_FALSE;
+};
+
+// Catch-all rule for pointer types.
+template <EntryPoint EP, typename PointerType>
+struct DefaultReturnValue<EP, const PointerType *>
+{
+    static constexpr const PointerType *kValue = nullptr;
+};
+
+template <EntryPoint EP, typename ReturnType>
+constexpr ANGLE_INLINE ReturnType GetDefaultReturnValue()
+{
+    return DefaultReturnValue<EP, ReturnType>::kValue;
+}
+
 }  // namespace gl
 
 #endif  // LIBANGLE_PARAMS_H_

src/libGLESv2/entry_points_gles_2_0_autogen.cpp

@@ -269,7 +269,7 @@ GLenum GL_APIENTRY CheckFramebufferStatus(GLenum target)
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::CheckFramebufferStatus, GLenum>();
 }
 
 void GL_APIENTRY Clear(GLbitfield mask)
@@ -505,7 +505,7 @@ GLuint GL_APIENTRY CreateProgram()
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::CreateProgram, GLuint>();
 }
 
 GLuint GL_APIENTRY CreateShader(GLenum type)
@@ -523,7 +523,7 @@ GLuint GL_APIENTRY CreateShader(GLenum type)
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::CreateShader, GLuint>();
 }
 
 void GL_APIENTRY CullFace(GLenum mode)
@@ -1071,7 +1071,7 @@ GLint GL_APIENTRY GetAttribLocation(GLuint program, const GLchar *name)
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::GetAttribLocation, GLint>();
 }
 
 void GL_APIENTRY GetBooleanv(GLenum pname, GLboolean *data)
@@ -1123,7 +1123,7 @@ GLenum GL_APIENTRY GetError()
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::GetError, GLenum>();
 }
 
 void GL_APIENTRY GetFloatv(GLenum pname, GLfloat *data)
@@ -1336,7 +1336,7 @@ const GLubyte *GL_APIENTRY GetString(GLenum name)
         }
     }
 
-    return nullptr;
+    return GetDefaultReturnValue<EntryPoint::GetString, const GLubyte *>();
 }
 
 void GL_APIENTRY GetTexParameterfv(GLenum target, GLenum pname, GLfloat *params)
@@ -1422,7 +1422,7 @@ GLint GL_APIENTRY GetUniformLocation(GLuint program, const GLchar *name)
         }
     }
 
-    return 0;
+    return GetDefaultReturnValue<EntryPoint::GetUniformLocation, GLint>();
 }
 
 void GL_APIENTRY GetVertexAttribfv(GLuint index, GLenum pname, GLfloat *params)
@@ -1508,7 +1508,7 @@ GLboolean GL_APIENTRY IsBuffer(GLuint buffer)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsBuffer, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsEnabled(GLenum cap)
@@ -1526,7 +1526,7 @@ GLboolean GL_APIENTRY IsEnabled(GLenum cap)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsEnabled, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsFramebuffer(GLuint framebuffer)
@@ -1544,7 +1544,7 @@ GLboolean GL_APIENTRY IsFramebuffer(GLuint framebuffer)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsFramebuffer, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsProgram(GLuint program)
@@ -1562,7 +1562,7 @@ GLboolean GL_APIENTRY IsProgram(GLuint program)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsProgram, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsRenderbuffer(GLuint renderbuffer)
@@ -1580,7 +1580,7 @@ GLboolean GL_APIENTRY IsRenderbuffer(GLuint renderbuffer)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsRenderbuffer, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsShader(GLuint shader)
@@ -1598,7 +1598,7 @@ GLboolean GL_APIENTRY IsShader(GLuint shader)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsShader, GLboolean>();
 }
 
 GLboolean GL_APIENTRY IsTexture(GLuint texture)
@@ -1616,7 +1616,7 @@ GLboolean GL_APIENTRY IsTexture(GLuint texture)
         }
     }
 
-    return GL_FALSE;
+    return GetDefaultReturnValue<EntryPoint::IsTexture, GLboolean>();
 }
 
 void GL_APIENTRY LineWidth(GLfloat width)