Editing String literal (section)

===Problems===
Implicit string concatenation is not required by modern compilers, which implement constant folding, and causes hard-to-spot errors due to unintentional concatenation from omitting a comma, particularly in vertical lists of strings, as in:
<syntaxhighlight lang="python">
l = ['foo',
     'bar'
     'zork']
</syntaxhighlight>
Accordingly, it is not used in most languages, and it has been proposed for deprecation from D<ref>DLang's Issue Tracking System – [https://issues.dlang.org/show_bug.cgi?id=3827 Issue 3827] - Warn against and then deprecate implicit concatenation of adjacent string literals</ref> and Python.<ref name=guidopythonideas/> However, removing the feature breaks backwards compatibility, and replacing it with a concatenation operator introduces issues of precedence – string literal concatenation occurs during lexing, prior to operator evaluation, but concatenation via an explicit operator occurs at the same time as other operators, hence precedence is an issue, potentially requiring parentheses to ensure desired evaluation order.

A subtler issue is that in C and C++,<ref>[[C++11]] draft standard, {{cite web | title=Working Draft, Standard for Programming Language C++ | url=http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf}}, 2.14.5 String literals [lex.string], note 13, p. 28–29: "Any other concatenations are conditionally supported with implementation-defined behavior."</ref> there are different types of string literals, and concatenation of these has implementation-defined behavior, which poses a potential security risk.<ref>{{cite web|url=https://www.securecoding.cert.org/confluence/display/seccode/STR10-C.+Do+not+concatenate+different+type+of+string+literals |title=STR10-C. Do not concatenate different type of string literals - Secure Coding - CERT Secure Coding Standards |access-date=July 3, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140714135237/https://www.securecoding.cert.org/confluence/display/seccode/STR10-C.+Do+not+concatenate+different+type+of+string+literals |archive-date=July 14, 2014 }}</ref>