"Johannes Schindelin via GitGitGadget" <gitgitgadget@xxxxxxxxx>
writes:
> From: Johannes Schindelin <johannes.schindelin@xxxxxx>
>
> This seems to be required to define `FLEX_ARRAY` in a manner that MSVC
> in C11 mode accepts. Without this fix, building Git for Windows'
> experimental FSCache code would fail thusly:
So, what's the final verdict on this one, after a few back and forth
to clarify the "seems to be required" above?
In the meantime, I am tempted to queue the following as a pure
clean-up.
Thoughts?
----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
Subject: [PATCH] flex-array: simplify compiler-specific workaround
We use "type array[];" syntax for the flex-array member at the end
of a struct under C99 or later, except when we are building with
older SUNPRO_C compilers. As we find more vendor compilers that
claim to grok C99 but not understand ts flex-array syntax, the
existing "If we are using C99, but not with these compilers..."
conditional will keep growing.
Make it more manageable by listing vendor-specific exceptions
earlier, with the expectation that new exceptions will not be
combined into existing ones to make the condition longer, and
instead will be implemented as a new "#elif" in the cascade of
#if/#elif/#else/#endif. E.g. if MSC is found to have a quirk
similar to old SUNPRO_C, we can just add a single line
#elif defined(_MSC_VER)
immediately before "#elif defined(__GNUC__)" to cause us to fallback
to the safer but a bit wasteful version.
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
git-compat-util.h | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git c/git-compat-util.h w/git-compat-util.h
index c6bd2a84e5..9ba047a58e 100644
--- c/git-compat-util.h
+++ w/git-compat-util.h
@@ -33,14 +33,23 @@
/*
* See if our compiler is known to support flexible array members.
*/
-#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) && (!defined(__SUNPRO_C) || (__SUNPRO_C > 0x580))
-# define FLEX_ARRAY /* empty */
+
+/*
+ * Check vendor specific quirks first, before checking the
+ * __STDC_VERSION__, as vendor compilers can lie and we need to be
+ * able to work them around. Note that by not defining FLEX_ARRAY
+ * here, we can fall back to use the "safer but a bit wasteful" one
+ * later.
+ */
+#if defined(__SUNPRO_C) && (__SUNPRO_C <= 0x580)
#elif defined(__GNUC__)
# if (__GNUC__ >= 3)
# define FLEX_ARRAY /* empty */
# else
# define FLEX_ARRAY 0 /* older GNU extension */
# endif
+#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
+# define FLEX_ARRAY /* empty */
#endif
/*
