[PATCH 6/6] New warnings -Wstring-plus-{char, int} (PR c++/62181)

[Xi Ruoyao <ryxi at stu dot xidian dot edu dot cn>]

This patch adds document of -Wstring-plus-int and -Wstring-plus-char.

gcc/ChangeLog:

2017-06-12  Xi Ruoyao  <ryxi@stu.xidian.edu.cn>

	* doc/invoke.texi (Warning Options): Document -Wstring-plus-int
	and -Wstring-plus-char.
---
 gcc/doc/invoke.texi | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

-- 
Xi Ruoyao <ryxi@stu.xidian.edu.cn>
School of Aerospace Science and Technology, Xidian University

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 5d41649..4859341 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -311,7 +311,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wsizeof-pointer-memaccess  -Wsizeof-array-argument @gol
 -Wstack-protector  -Wstack-usage=@var{len}  -Wstrict-aliasing @gol
 -Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol
--Wstringop-overflow=@var{n} @gol
+-Wstringop-overflow=@var{n} @gol -Wstring-plus-char -Wstring-plus-int
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol
 -Wsuggest-final-types @gol  -Wsuggest-final-methods  -Wsuggest-override @gol
 -Wmissing-format-attribute  -Wsubobject-linkage @gol
@@ -5125,6 +5125,26 @@ whether to issue a warning.  Similarly to @option{-Wstringop-overflow=3} this
 setting of the option may result in warnings for benign code.
 @end table
 
+@item -Wstring-plus-char
+@opindex Wstring-plus-char
+@opindex Wno-string-plus-char
+Warn for adding a character to a string pointer, which seems like a failed
+attempt to append to the string.  For example, this option will issue a
+warning for the code below.
+
+@smallexample
+const char *p = "abc", *q;
+q = p + 'a';
+@end smallexample
+
+@item -Wstring-plus-int
+@opindex Wstring-plus-int
+@opindex Wno-string-plus-int
+Warn for adding an integer to a string literal, which may forms a pointer
+out of the bound of the string.  The typical examples this warns about are
+@samp{"abc" + 'd'}, @samp{"abc" + getchar()} and @samp{"abc" + 5}, but
+not @samp{"abc" + 1}.
+
 @item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]}
 @opindex Wsuggest-attribute=
 @opindex Wno-suggest-attribute=
-- 
2.7.1