makefile: demote -Werror=c++-compat to a warning

Also edited CONTRIBUTING.md and a comment in common.h accordingly to reflect this change.

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 56beb08f638b9c87649664f715c39f7e20669ca6..f68358857f3f975aabfe1f9b85ecef69485f5419 100644 (file)
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -101,20 +101,31 @@
                if (boo)  AHH("!!!\n");
                ```
 
-4. DarkPlaces is written in a special subset of C and C++ that sits in the
-   center of the Venn diagram of compatibility between the two languages.
-   While there is no practical reason for keeping it this way (yet), it is
-   generally preferred that all code submitted at least compiles under gcc and
-   g++ and clang(++). This could be done by setting the CC environment
-   variable to g++ or clang++ on the command-line before building.
-
-   Most of the differences are enforced by a compile warning set to be an
-   error (`-Werror=c++-compat`) but some are subtle and would cause behavior
-   differences between the two compilers, or are not caught by that warning.
-   The things to look out for are:
+4. DarkPlaces is written in the common subset of C and C++. This means it is
+   (usually) both valid C and C++. We historically wanted to keep it that way,
+   but don't worry about it unless you care enough and/or are a maintainer.
+
+   Most of the differences are caught by `-Wc++-compat` but some are subtle
+   and would cause behavior differences between the two compilers, or are not
+   caught by that warning. The things to look out for are:
 
        1. Character constants are `int`-sized in C but `char`-sized in C++. This
-       means `sizeof('a')` will be 4 in C, but 1 in C++.
+          means `sizeof('a')` will be 4 in C, but 1 in C++.
 
        2. `goto label;` cannot jump over a variable initialization. This will
-       cause a compiler error as C++ but is not caught by `-Wc++-compat`.
+          cause a compiler error as C++ but is not caught by `-Wc++-compat`.
+          This is nevertheless bad code, so avoid this anyway.
+
+   If, for some reason, you care enough, compatibility can always be tested
+   affirmatively by setting CC=g++. CC=clang++ may not work in the future, if
+   it did not already stop working in current versions LLVM, as it otherwise
+   spams deprecation warnings for using a C file asinput to a C++ compiler.
+
+> [!NOTE]
+> We do not officially support building C code with a C++ compiler and may not
+> address issue reports for buggy behavior that does not occur when compiled
+> with a C compiler. That said, there have been fleeting ideas for converting
+> either the entire engine or parts of it to C++, which is what `-Wc++-compat`
+> would make a little easier. So, we at least *do not discourage* such issue
+> reports, especially for things the warning doesn't catch. They will be noted
+> as they would become relevant in the event we do decide to convert to C++.
\ No newline at end of file

diff --git a/common.h b/common.h
index 5b73aa6f6c4d9a5e0fd0bff5a21eac16c87ad24a..cde830dcfdc7e51fac232f75fee227459d8cfbcd 100644 (file)
--- a/common.h
+++ b/common.h
@@ -221,7 +221,12 @@ void COM_Shutdown (void);
 char *va(char *buf, size_t buflen, const char *format, ...) DP_FUNC_PRINTF(3);
 // does a varargs printf into provided buffer, returns buffer (so it can be called in-line unlike dpsnprintf)
 
-// GCC with -Werror=c++-compat will error out if static_assert is used even though the macro is valid C11...
+/* Some versions of GCC with -Wc++-compat will complain if static_assert
+ * is used even though the macro is valid C11, so make it happy anyway
+ * because having build logs without any purple text is pretty satisfying.
+ * TODO: Disable the flag by default in makefile, with an optional variable
+ * to reenable it.
+ */
 #ifndef __cplusplus
 #define DP_STATIC_ASSERT(expr, str) _Static_assert(expr, str)
 #else

diff --git a/makefile.inc b/makefile.inc
index dc9c990e31dab1754b8e40414b320db135f98ed4..33cbc0438525ef568d77e9858a68673580f2f160 100644 (file)
--- a/makefile.inc
+++ b/makefile.inc
@@ -139,7 +139,7 @@ else
        CFLAGS_STANDARD=
 endif
 
-CFLAGS_WARNINGS=-Wall -Werror=vla -Werror=c++-compat -Wwrite-strings -Wshadow -Wold-style-definition -Wstrict-prototypes -Wsign-compare -Wdeclaration-after-statement -Wmissing-prototypes
+CFLAGS_WARNINGS=-Wall -Werror=vla -Wc++-compat -Wwrite-strings -Wshadow -Wold-style-definition -Wstrict-prototypes -Wsign-compare -Wdeclaration-after-statement -Wmissing-prototypes
 
 CFLAGS_TCC=
 ifeq ($(CC), tcc)