[ruby-core:103040] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[ruby-core:103040] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been reported by Eregon (Benoit Daloze).

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?



-- 
https://bugs.ruby-lang.org/

[ruby-core:103050] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


I think it's just a matter of coding style to allow evaluating undefined identifiers, whether it is good or bad.

The example of `ext/nkf/nkf-utf8/nkf.h` seems intentional, just not bothering to write:
```c
#ifndef DEFAULT_NEWLINE
#define DEFAULT_NEWLINE 0
#endif
```

If this practice should be error-prone, we might have to change the style. I am neutral for now.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91111

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?



-- 
https://bugs.ruby-lang.org/

[ruby-core:103059] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).


The `#if UNDEFINED_IDENTIFIER` seems fairly rare (56 vs 637), so it also seems more consistent to always use `#ifdef` if the identifier might not always be defined.

One example is:
```c
#if HAVE_RB_EXT_RACTOR_SAFE
```
vs
```c
#ifdef HAVE_RB_EXT_RACTOR_SAFE
```

The second seems better to me, and is more explicit about the fact this might not be defined.
The value of the macro ultimately does not matter for all `HAVE_` macros.


----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91120

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?



-- 
https://bugs.ruby-lang.org/

[ruby-core:103060] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).

File ruby-USE_BACKTRACE.patch added

> The value of the macro ultimately does not matter for all `HAVE_` macros.

There is a counterexample: `HAVE_BACKTRACE` in `vm_dump.c`, which is redefined as 0 when `BROKEN_BACKTRACE` is defined. I feel this to be an abuse of `HAVE_` macros, and I would like to define a new macro `USE_BACKTRACE` indicating whether `backtrace` should be used or not, as in the attached patch.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91121

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103061] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).


Indeed, and that patch looks good to me.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91122

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103079] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[shyouhei]

Issue #17752 has been updated by shyouhei (Shyouhei Urabe).


As far as the effect of `-Wundef` do not leak to 3rd party extension libraries, yes I'm in favor of it.  It sounds a bit too harsh for 3rd parties.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91140

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103262] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).

File ruby-trivial-undefined-macros.patch added
File ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch added
File ruby-BIGNUM_EMBED_LEN_MAX.patch added

Using `-Wundef` I saw that the definitions of `BIGNUM_EMBED_LEN_MAX` and `COROUTINE_LIMITED_ADDRESS_SPACE` might be incorrect. Patches are attached to fix them.

Also attached is another patch to calm down `-Wundef` warnings that seem to be trivial.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91345

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103268] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


I noticed that `-Wundef` is explicitly disabled for GCC at [include/ruby/internal/token_paste.h:40](https://github.com/ruby/ruby/blob/587e6800086764a1b7c959976acef33e230dccc2/include/ruby/internal/token_paste.h#L40):

```c
#if RBIMPL_COMPILER_SINCE(GCC, 4, 2, 0)
# /* GCC is one of such compiler who  cannot write `_Pragma` inside of a `#if`.
#  * Cannot but globally kill everything.  This  is of course a very bad thing.
#  * If you know how to reroute this please tell us. */
# /* https://gcc.godbolt.org/z/K2xr7X */
# define RBIMPL_TOKEN_PASTE(x, y) TOKEN_PASTE(x, y)
# pragma GCC diagnostic ignored "-Wundef"
# /* > warning: "symbol" is not defined, evaluates to 0 [-Wundef] */
```

The problem is that GCC is a major compiler that is widely used in CI, and so we will still be missing a lot of potential problems even if `-Wundef` is enabled by default.


----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91353

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103326] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[shyouhei]

Issue #17752 has been updated by shyouhei (Shyouhei Urabe).


xtkoba (Tee KOBAYASHI) wrote in #note-7:
> I noticed that `-Wundef` is explicitly disabled for GCC at [include/ruby/internal/token_paste.h:40](https://github.com/ruby/ruby/blob/587e6800086764a1b7c959976acef33e230dccc2/include/ruby/internal/token_paste.h#L40):

Ah yes I remember.  This is because for instance `TOKEN_PASTE(re, strict)` issues undefined macro warning for "re", in spite of the rendered token `restrict` being valid.

PS. `TOKEN_PASTE` is a macro defined by configure.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91417

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103339] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[shyouhei]

Issue #17752 has been updated by shyouhei (Shyouhei Urabe).


My attempt https://github.com/ruby/ruby/pull/4371

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91430

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103425] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).


@xtkoba Your 4 patches look good to me, could you commit them?

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91518

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103444] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).

File ruby-trivial-undefind-macros-0002.patch added

Thanks to user:shyouhei's work, we are now able to notice undefined identifiers evaluated in `#if` directives using GCC with `-Wundef`.

I attach an additional patch that fixes undefined identifiers from being evaluated.

Note that there must still remain a whole bunch of `#if HAVE_...` that I do not aware of because it is defined in my environment.

user:Eregon I am not sure these patches conform to the coding style. Especally I doubt if the macro of the name `_RVALUE_EMBED_LEN_MAX` is allowed. Could anyone brush up and commit them in place of me?

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91536

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103656] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).

Target version set to 3.1
Assignee set to Eregon (Benoit Daloze)

I made a PR with @xtkoba's patches and additional fixes, as well as enabling undef warnings:
https://github.com/ruby/ruby/pull/4428

@xtkoba Importing patches is quite time-consuming, it would be better if you can already make commits, with a PR or just on a branch next time.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91752

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103657] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


user:Eregon Thank you very much. I have just learnt how to use GitHub. I will do it by myself next time.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91753

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103717] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[mame]

Issue #17752 has been updated by mame (Yusuke Endoh).

Status changed from Closed to Assigned

I think this change broke the following servers on RubyCI.

* [Ubuntu armv7l eabihf](http://rubyci.s3.amazonaws.com/scw-9d6766/ruby-master/log/20210504T221708Z.fail.html.gz)
* [CentOS 7.6(1810) x86_64](http://rubyci.s3.amazonaws.com/centos7/ruby-master/log/20210504T213003Z.fail.html.gz)
* [RHEL 7.1 s390x](http://rubyci.s3.amazonaws.com/rhel_zlinux/ruby-master/log/20210504T213302Z.fail.html.gz)
* [FreeBSD 12.2 x64](http://rubyci.s3.amazonaws.com/freebsd12/ruby-master/log/20210504T223001Z.fail.html.gz)
* [macOS Big Sur (ARM)](http://rubyci.s3.amazonaws.com/osx1100arm/ruby-master/log/20210504T214504Z.fail.html.gz)

@eregon Could you please fix them?

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91811

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103718] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[mame]

Issue #17752 has been updated by mame (Yusuke Endoh).


Maybe [icc 2021.2 x64](http://rubyci.s3.amazonaws.com/icc-x64/ruby-master/log/20210504T190003Z.fail.html.gz) is also broken.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91812

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103720] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


I propose `-Wundef` warnings not be made into errors for the time being.

PR: https://github.com/ruby/ruby/pull/4455

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91814

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103721] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).


I'll take a look tomorrow.
If we need a fix faster, I think it's OK to merge @xtkoba's PR.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91815

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103723] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


The remaining problems seem due to insufficient simulation of `RBIMPL_HAS_*` in `include/ruby/internal/has/*` for GCC <= 4.x and ICC.

My temporary patch would not be necessary if errors did not manifest themselves one after another.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91817

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103728] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[xtkoba+ruby]

Issue #17752 has been updated by xtkoba (Tee KOBAYASHI).


I missed one more error, for which a new ticket is open now (#17850).

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91822

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103729] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[mame]

Issue #17752 has been updated by mame (Yusuke Endoh).


* @nobu fixed the error on old GCC: 5bde2e61db8148cd5a7974f640aee38be60bf368
* I think I fixed the error on icc (but not confirmed yet): e71c9ca529f1dce2c3816653cd974ce786eea7d8
* @nobu is now creating a patch fo M1 macOS.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91823

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103733] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[eregontp]

Issue #17752 has been updated by Eregon (Benoit Daloze).


https://rubyci.org/ looks good now except `macOS Big Sur (ARM)`, thank you @mame, @nobu, @xtkoba for the fixes, and sorry for the breakage (the CI on GitHub passed).


----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91828

* Author: Eregon (Benoit Daloze)
* Status: Assigned
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/

[ruby-core:103737] [Ruby master Feature#17752] Enable -Wundef for C extensions in repository

[mame]

Issue #17752 has been updated by mame (Yusuke Endoh).

Status changed from Assigned to Closed

@eregon No worries. This change revealed an actual issue #17850 anyway, great! I think other issues than #17850 are all addressed, so I'm closing this ticket.

----------------------------------------
Feature #17752: Enable -Wundef for C extensions in repository
https://bugs.ruby-lang.org/issues/17752#change-91832

* Author: Eregon (Benoit Daloze)
* Status: Closed
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* Target version: 3.1
----------------------------------------
I would like to enable `-Wundef` for C extensions built/bundled with CRuby.

From https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
> -Wundef
>    Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

I found this warning to be quite useful, notably when investigating why a given C extension did not include some code I expected, and then building those extensions on TruffleRuby.

There are a couple places not respecting this currently but they seem trivial to fix, I can do that.

For instance a confusing case is:
https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/ext/nkf/nkf-utf8/nkf.h#L19
```
#if DEFAULT_NEWLINE == 0x0D0A
```
which without -Wundef would just exclude the code without any warning if DEFAULT_NEWLINE is not defined.

I'm not sure if we should/can enable it for C extensions in general (installed as gems), as if a C extensions uses -Werror and would have such a warning it would no longer build.

I can make a PR for this.
I'm not sure where to add -Wundef though, should it be in https://github.com/ruby/ruby/blob/9143d21b1bf2f16b1e847d569a588510726d8860/configure.ac#L620, or maybe in mkmf.rb?

---Files--------------------------------
ruby-USE_BACKTRACE.patch (1.21 KB)
ruby-BIGNUM_EMBED_LEN_MAX.patch (950 Bytes)
ruby-COROUTINE_LIMITED_ADDRESS_SPACE.patch (711 Bytes)
ruby-trivial-undefined-macros.patch (4.35 KB)
ruby-trivial-undefind-macros-0002.patch (1.44 KB)


-- 
https://bugs.ruby-lang.org/