http://llvm.org/bugs/show_bug.cgi?id=9544
Summary: Static Analyzer should warn about usage of weak
symbols without check.
Product: clang
Version: trunk
Platform: All
OS/Version: MacOS X
Status: NEW
Severity: enhancement
Priority: P
Component: Static Analyzer
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Created an attachment (id=6358)
--> (http://llvm.org/bugs/attachment.cgi?id=6358)
Example
When using a symbol declared as weak_import, the symbol may be set to null at
launch time by the dynamic linker if it is not available.
So when calling a weak function, the user has to check that the symbol is valid
and not null.
This is a special case of 'null deref', so maybe it can be done using the
existing null deref checker.
For example:
--------------------
extern int foo() __attribute__((weak_import,visibility("default")));
extern const char * const kGlobalStringSymbol
__attribute__((weak_import,visibility("default")));
int test(char *arg) {
if (0 == strcmp(kGlobalStringSymbol, arg)) // expected warning: use of weak
symbol 'kGlobalStringSymbol' which may be null
return 0;
return foo(); // expect warning: use of weak symbol 'foo' which may be null
}
int test2(char *arg) {
if (&kGlobalStringSymbol && 0 == strcmp(kGlobalStringSymbol, arg)) // no
warning
return 0;
return foo ? foo() : 0; // no warning
}
--------------------
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