Allow double underscore in macro names

src/compiler/preprocessor/DiagnosticsBase.cpp

@@ -125,6 +125,8 @@ std::string Diagnostics::message(ID id)
         return "unrecognized pragma";
       case PP_NON_PP_TOKEN_BEFORE_EXTENSION_ESSL1:
         return "extension directive should occur before any non-preprocessor tokens";
+      case PP_WARNING_MACRO_NAME_RESERVED:
+        return "macro name with a double underscore is reserved - unintented behavior is possible";
       // Warnings end.
       default:
         assert(false);

src/compiler/preprocessor/DiagnosticsBase.h

@@ -71,6 +71,7 @@ class Diagnostics
         PP_EOF_IN_DIRECTIVE,
         PP_UNRECOGNIZED_PRAGMA,
         PP_NON_PP_TOKEN_BEFORE_EXTENSION_ESSL1,
+        PP_WARNING_MACRO_NAME_RESERVED,
         PP_WARNING_END
     };
 

src/compiler/preprocessor/DirectiveParser.cpp

@@ -119,14 +119,12 @@ void skipUntilEOD(pp::Lexer *lexer, pp::Token *token)
 bool isMacroNameReserved(const std::string &name)
 {
     // Names prefixed with "GL_" are reserved.
-    if (name.substr(0, 3) == "GL_")
-        return true;
-
-    // Names containing two consecutive underscores are reserved.
-    if (name.find("__") != std::string::npos)
-        return true;
+    return (name.substr(0, 3) == "GL_");
+}
 
-    return false;
+bool hasDoubleUnderscores(const std::string &name)
+{
+    return (name.find("__") != std::string::npos);
 }
 
 bool isMacroPredefined(const std::string &name,
@@ -291,6 +289,16 @@ void DirectiveParser::parseDefine(Token *token)
                              token->location, token->text);
         return;
     }
+    // Using double underscores is allowed, but may result in unintended
+    // behavior, so a warning is issued. At the time of writing this was
+    // specified in ESSL 3.10, but the intent judging from Khronos
+    // discussions and dEQP tests was that double underscores should be
+    // allowed in earlier ESSL versions too.
+    if (hasDoubleUnderscores(token->text))
+    {
+        mDiagnostics->report(Diagnostics::PP_WARNING_MACRO_NAME_RESERVED, token->location,
+                             token->text);
+    }
 
     Macro macro;
     macro.type = Macro::kTypeObj;

src/tests/deqp_support/deqp_gles2_test_expectations.txt

@@ -235,8 +235,6 @@
 504 WIN LINUX : dEQP-GLES2.functional.uniform_api.value.assigned.by_value.render.nested_structs_arrays.sampler2D_samplerCube_* = FAIL
 
 // Windows Linux and Mac failures
-989 WIN LINUX MAC : dEQP-GLES2.functional.shaders.preprocessor.basic.identifier_with_double_underscore_vertex = FAIL
-989 WIN LINUX MAC : dEQP-GLES2.functional.shaders.preprocessor.basic.identifier_with_double_underscore_fragment = FAIL
 989 WIN LINUX MAC : dEQP-GLES2.functional.shaders.preprocessor.extensions.after_non_preprocessing_tokens_vertex = FAIL
 989 WIN LINUX MAC : dEQP-GLES2.functional.shaders.preprocessor.extensions.after_non_preprocessing_tokens_fragment = FAIL
 1015 WIN LINUX MAC : dEQP-GLES2.functional.shaders.functions.invalid.return_array_in_struct_vertex = FAIL

src/tests/deqp_support/deqp_gles3_test_expectations.txt

@@ -42,8 +42,6 @@
 
 1087 WIN : dEQP-GLES3.functional.implementation_limits.num_compressed_texture_formats = FAIL
 1087 WIN : dEQP-GLES3.functional.implementation_limits.compressed_texture_formats = FAIL
-989 WIN : dEQP-GLES3.functional.shaders.preprocessor.basic.identifier_with_double_underscore_vertex = FAIL
-989 WIN : dEQP-GLES3.functional.shaders.preprocessor.basic.identifier_with_double_underscore_fragment = FAIL
 1088 WIN : dEQP-GLES3.functional.shaders.linkage.varying.rules.invalid_type_struct_array = FAIL
 1088 WIN : dEQP-GLES3.functional.shaders.linkage.varying.rules.invalid_type_struct_struct = FAIL
 1088 WIN : dEQP-GLES3.functional.shaders.linkage.varying.rules.invalid_type_array_struct = FAIL

src/tests/preprocessor_tests/define_test.cpp

@@ -70,12 +70,10 @@ TEST_F(DefineTest, ReservedUnderScore1)
     const char* input = "#define __foo bar\n"
                         "__foo\n";
     const char* expected = "\n"
-                           "__foo\n";
+                           "bar\n";
 
-    EXPECT_CALL(mDiagnostics,
-                print(pp::Diagnostics::PP_MACRO_NAME_RESERVED,
-                      pp::SourceLocation(0, 1),
-                      "__foo"));
+    EXPECT_CALL(mDiagnostics, print(pp::Diagnostics::PP_WARNING_MACRO_NAME_RESERVED,
+                                    pp::SourceLocation(0, 1), "__foo"));
 
     preprocess(input, expected);
 }
@@ -85,12 +83,10 @@ TEST_F(DefineTest, ReservedUnderScore2)
     const char* input = "#define foo__bar baz\n"
                         "foo__bar\n";
     const char* expected = "\n"
-                           "foo__bar\n";
+                           "baz\n";
 
-    EXPECT_CALL(mDiagnostics,
-                print(pp::Diagnostics::PP_MACRO_NAME_RESERVED,
-                      pp::SourceLocation(0, 1),
-                      "foo__bar"));
+    EXPECT_CALL(mDiagnostics, print(pp::Diagnostics::PP_WARNING_MACRO_NAME_RESERVED,
+                                    pp::SourceLocation(0, 1), "foo__bar"));
 
     preprocess(input, expected);
 }