blocks|key|3665946|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3665947|我猜这是因为__attribute__+((always_inline))暗示了inline+-在这种情况下，属性的解析需要设置DECL_DECLARED_INLINE_P。|offset|length|style|CODE|3665948|《GCC手册》规定|3665949|3665950|+always_inline通常，除非指定了优化，否则函数不会内联。对于内联声明的函数，即使没有指定优化级别，此属性也会内联函数。|blockquote|3665951|3665952|3665953|以下是修订版的gcc+test|3665954|entityMap|0|LINK|mutability|MUTABLE|url|https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/testsuite/gcc.dg/vmx/gcc-bug-i.c?view=markup&pathrev=178730^0|0|6|V|14|6|1S|M|0|0|0|0|0|0|7|3|B|4|0|0^^$0|@$1|2|3|-4|4|5|6|Y|7|@]|8|@]|9|$]]|$1|A|3|B|4|5|6|Z|7|@$C|10|D|11|E|F]|$C|12|D|13|E|F]|$C|14|D|15|E|F]]|8|@]|9|$]]|$1|G|3|H|4|5|6|16|7|@]|8|@]|9|$]]|$1|I|3|-4|4|5|6|17|7|@]|8|@]|9|$]]|$1|J|3|K|4|L|6|18|7|@]|8|@]|9|$]]|$1|M|3|-4|4|5|6|19|7|@]|8|@]|9|$]]|$1|N|3|-4|4|5|6|1A|7|@]|8|@]|9|$]]|$1|O|3|P|4|5|6|1B|7|@$C|1C|D|1D|E|F]]|8|@$C|1E|D|1F|1|1G]]|9|$]]|$1|Q|3|-4|4|5|6|1H|7|@]|8|@]|9|$]]]|R|$S|$4|T|U|V|9|$W|X]]]]

What that warning is saying is that the compiler, is not always happy accepting your function as inline, or it wants it to be declared as inline. 

I guess it's that <code>__attribute__ ((always_inline))</code> implies <code>inline</code> - in which case the parsing of the attribute needs to set <code>DECL_DECLARED_INLINE_P</code>.

The GCC manual specifies 

<blockquote>
 always_inline Generally, functions are not inlined unless optimization is specified. For functions declared inline, this attribute inlines the function even if no optimization level is specified.
</blockquote>

Here's the <code>gcc</code> <a href="https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/testsuite/gcc.dg/vmx/gcc-bug-i.c?view=markup&amp;pathrev=178730" rel="nofollow">test</a> for the revision

blocks|key|3665969|text|经过两天的努力，终于找到了解决方案，如下所示|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3665970|这只是因为Makefile+CFLAGS=+-D+inline中的编译器(arm-none-eabi-gcc)选项。如果设置了此标志，则在尝试包含始终包含内联函数的.h文件时，会抛出警告为__attribute__(+(+always_inline+)+)+__STATIC_INLINE(inline)+uint32_t+__SLA+(int32_t+o1,+int32_t+o2,+int32_t+o3)|offset|length|style|CODE|3665971|entityMap^0|0|E|H|2M|32|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]|$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|I|$]]

<h2>finally, after spending two days efforts found the solution as it is below</h2>

it is just because of a compiler(arm-none-eabi-gcc) option in Makefile
<code>CFLAGS= -D inline</code> if this flag is set, it throws warning as <code>__attribute__( ( always_inline ) ) __STATIC_INLINE(inline) uint32_t __SLA (int32_t o1, int32_t o2, int32_t o3)</code> when trying to include a .h file which consists of always inline functions

blocks|key|622668|text|For+functions+declared+inline(!!!!)，这个属性独立于任何其他应用于内联的限制来内联函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|622669|所以，当你在没有声明内联函数的情况下设置属性时，你会得到这些警告。另外声明内联函数将使这些警告无效。行为gnu+gcc/g%2B%2B+5.30|622670|#+define+FORCE_INLINE+__attribute__((always_inline))+inline

FORCE_INLINE+vec3+operator-+(vec3+a,+vec3+b)+{+vec3+t+=+{+a.x-b.x,+a.y-b.y,+a.z-b.z+};+return+t;+}|code-block|syntax|javascript|622671|entityMap|0|LINK|mutability|MUTABLE|url|https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html^0|0|Z|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

<a href="https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html">For functions declared inline(!!!!)</a>, this attribute inlines the function independent of any restrictions that otherwise apply to inlining.

So, when you set the attribute without declaring the function inline you will get these warning. Declare the function additionally inline will void these warnings. Behavior gnu gcc/g++ 5.30

<pre><code># define FORCE_INLINE __attribute__((always_inline)) inline

FORCE_INLINE vec3 operator- (vec3 a, vec3 b) { vec3 t = { a.x-b.x, a.y-b.y, a.z-b.z }; return t; }
</code></pre>

when i try to include a .h file which consists of definition for inline functions as 

<pre><code>__attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __SLA (int32_t o1, int32_t o2, int32_t o3)
</code></pre>

it is giving the "warning: always_inline function might not be inlinable [-Wattributes]" can you somebody help me i am struggling to fix it.

warning: always_inline function might not be inlinable [-Wattributes]

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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当我尝试包含一个由内联函数定义组成的.h文件时，__attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __SLA (int32_t o1, int32_t o2, int32_t o3)它给出了"warning: always_inline functi...

问警告: always_inline函数可能无法内联[-Wattributes]
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问警告: always_inline函数可能无法内联[-Wattributes]EN