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diff --git a/share/doc/cpp/Directives-Within-Macro-Arguments.html b/share/doc/cpp/Directives-Within-Macro-Arguments.html new file mode 100644 index 0000000..0034cd8 --- /dev/null +++ b/share/doc/cpp/Directives-Within-Macro-Arguments.html @@ -0,0 +1,114 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1987-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation. A copy of +the license is included in the +section entitled "GNU Free Documentation License". + +This manual contains no Invariant Sections. 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The C and C++ standards declare that +behavior in these cases is undefined. GNU CPP +processes arbitrary directives within macro arguments in +exactly the same way as it would have processed the directive were the +function-like macro invocation not present. +</p> +<p>If, within a macro invocation, that macro is redefined, then the new +definition takes effect in time for argument pre-expansion, but the +original definition is still used for argument replacement. Here is a +pathological example: +</p> +<div class="smallexample"> +<pre class="smallexample">#define f(x) x x +f (1 +#undef f +#define f 2 +f) +</pre></div> + +<p>which expands to +</p> +<div class="smallexample"> +<pre class="smallexample">1 2 1 2 +</pre></div> + +<p>with the semantics described above. +</p> + + + +</body> +</html> |