C define highlighting can be wrong with C++ grammar but not in C grammar

[alexr00]

From @jaudiger in https://github.com/microsoft/vscode/issues/82848

• VSCode Version: 1.39.2
• OS Version: Windows 10 (64 bits) + ArchLinux WSL

Steps to Reproduce:

1. Use the following code inside a test.c(uses C grammar) file and a test.h(uses C++ grammar) file:

#define A 1
#define B 2

#define E (A | B)

2. The file test.h(using the C++ grammar) contains a wrong highlighting define for E: A is not of the same color as B.

Does this issue occur when C/C++ extension is disabled?: Yes

[rianquinn]

I can confirm this issue with mine as well. Might be related to the issue I just posted.

[matter123]

This is caused by the grammar treating any #define foo (/* snip */) as a macro function even when it contains invalid characters.

It should be easy enough to restrict a macro function definition to:

• identifiers
• spaces
• comments
• commas
• ... as the last item

Standard reference: http://eel.is/c++draft/gram.cpp

[sean-mcmanus]

A user reported another repro with

#define ITEM_MASK 0x00000001U /**< Documentation
                                   that goes onto the next line */

It seems like that's the same issue as this? Only repros with C++ and not C.