clang and analyzer don't complain about conditions that are always true

[llvmbot]

Bugzilla Link	18050
Version	trunk
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@AnnaZaks,@belkadan,@rnk,@Weverything

Extended Description

static NSString *const bla = @"bla";

if (bla) NSLog(@"always true");

if (@"blabla") NSLog(@"always true");

both conditions don't generate a warning with clang even with -Weverything and even the static analyzer doesn't complain although the conditions are bound to be always true.

[Weverything]

r200356 now makes Clang catch Objective-C object literal to bool conversions. On by default, or use -Wobjc-literal-conversion. So this will warn on the example of:

if (@"blabla")

[Weverything]

http://llvm-reviews.chandlerc.com/D2608

This is a patch to extend -Wstring-conversion to catch "if(@"blabla")"

[llvmbot]

shouldn't Wstring-conversion also catch the second case?

"Due to that, -Wstring-conversion will warn when a string literal is converted to a true boolean value. "

only works for C strings and not ObjC strings?

[0f73b9cf-134f-41af-a8b1-14d9f305ee95]

Wouldn't this be better suited for a compiler warning?

[belkadan]

The static analyzer isn't usually very good at answering questions that are true on /all/ paths; it's better at finding /any/ path. But we can probably contrive a way to handle the first case, and the second case could probably be implemented just with the constant evaluator.

[llvmbot]

assigned to @tkremenek