Improve handling of adjacent string literals of different types.
Example of adjacent string literals: "ab" L"cd".
In C89, C++98 and C++03, this is undefined. As of C99 and C++11, this is
well defined and the two string literals are concatenated to L"abcd".
C11 and C++11 introduces the utf16, utf32 and (C++ only) utf8 string
types. Concatenating any of these with a regular c-string works exactely
as the wide string example above. The result of having two adjacent
string literals with different prefix is implementation defined, unless
one is an UTF-8 string literal and the other is a wide string literal.
In this case the behaviour is undefined.
Ignore the undefined and ill-formed programs (this behaviour is unchanged)
and make sure that concatenating a plain c string literal with a prefixed
one works correct (in C99 and C++11 and later versions). It also makes the
behaviour consistent since previously, "ab" L"cd" would result in "abcd"
while L"ab" "cd" would result in L"abcd".
It also means the somewhat awkward updatePropertiesConcatStr() test can
be removed since the added tests would not work if update_properties()
was not called in concatStr().
Since the prefix is stored in the token, testing the type of the string
is not relevant in TestSimplifyTokens. It is tested extensively in
TestToken::stringTypes().
* Set correct type and size of string and char literals
Use that string and char literal tokens store the prefix. This makes
it possible to distinghuish between different type of string literals
(i.e., utf8 encoded strings, utf16, wide strings, etc) which have
different type.
When the tokens holding the string and character values have the correct
type, it is possible to improve Token::getStrSize() to give the correct
result for all string types. Previously, it would return the number of
characters in the string, i.e., it would give the wrong size unless
the type of the string was char*.
Since strings now can have different size (in number of bytes) and
length (in number of elements), add a new helper function that returns
the number of characters. Checkers have been updated to use the correct
functions.
Having the size makes it possible to find more problems with prefixed
strings, and to reduce false positives, for example in the buffer
overflow checker.
Also, improve the stringLiteralWrite error message to also print the
prefix of the string (if there is one).
* Add comment and update string length
Keeping the prefix in the token allows cppcheck to print the correct
string and char literals in debug and error messages.
To achieve this, move some of the helper functions from token.cpp to
utils.h so that checks that look at string and char literals can reuse
them. This is a large part of this commit.
Note that the only user visible change is that when string and char
literals are printed in error messages, the prefix is now included.
For example:
int f() {
return test.substr( 0 , 4 ) == U"Hello" ? 0 : 1 ;
};
now prints U"Hello" instead of "Hello" in the error message.
Paul Fultz II
IOBYTE
orbitcowboy
Oliver Stöneberg
Rikard Falkeborn
Daniel Marjamäki
shaneasd
PKEuS