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From: "gcc at behdad dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug preprocessor/100125] New: -Wunused-macros generated while should be ignored; if undef is seen?
Date: Fri, 16 Apr 2021 20:30:22 +0000	[thread overview]
Message-ID: <bug-100125-4@http.gcc.gnu.org/bugzilla/> (raw)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100125

            Bug ID: 100125
           Summary: -Wunused-macros generated while should be ignored; if
                    undef is seen?
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at behdad dot org
  Target Milestone: ---

We're facing this in HarfBuzz. I narrowed down the bug to this:

Works:

```c++
#pragma GCC diagnostic ignored "-Wunused-macros"

#define A B
```

$ g++ a.cc -c -Wunused-macros

(fine; no warning)

But if I add an `undef` to that file:

```c++
#pragma GCC diagnostic ignored "-Wunused-macros"

#define A B

#undef A
```

$ g++ a.cc -c -Wunused-macros
a.cc:3: warning: macros "A" is not used [-Wunused-macros]
    3 | #define A B

Am I missing something?

             reply	other threads:[~2021-04-16 20:30 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 20:30 gcc at behdad dot org [this message]
2022-06-29 16:08 ` [Bug preprocessor/100125] " lhyatt at gcc dot gnu.org

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