r263299 - Add fix-it for format-security warnings.

David Blaikie via cfe-commits cfe-commits at lists.llvm.org
Fri Mar 11 16:15:28 PST 2016


On Fri, Mar 11, 2016 at 4:14 PM, Bob Wilson via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> I’m not sure how to interpret that. It says: "Clang must recover from
> errors as if the fix-it had been applied.” I suppose that format-security
> could be an error if you’re building with -Werror, but I had been
> interpreting that to mean an error that would block further compilation.
> Can someone clarify this expectation?
>
> I don’t think we can change -Wformat-security to be a note.
>

The suggestion isn't to change it to be a note, but to keep the warning but
move the fixit to a note associated with the warning.

That way -fix-it doesn't automatically apply the fix-it, which avoids the
issue of recovery as-if the fixit was applied.


> It is an existing warning, and people expect us to match GCC on it as well.
>
>
> On Mar 11, 2016, at 4:03 PM, Nico Weber <thakis at chromium.org> wrote:
>
> I think http://clang.llvm.org/docs/InternalsManual.html#fix-it-hints says
> that if a fixit is on a warning, then clang should process the code as if
> the fixit had been applied. That's not the case here, so I think the fixit
> should be on a note instead.
>
> On Fri, Mar 11, 2016 at 4:55 PM, Bob Wilson via cfe-commits <
> cfe-commits at lists.llvm.org> wrote:
>
>> Author: bwilson
>> Date: Fri Mar 11 15:55:37 2016
>> New Revision: 263299
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=263299&view=rev
>> Log:
>> Add fix-it for format-security warnings.
>>
>> Added:
>>     cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m
>> Modified:
>>     cfe/trunk/lib/Sema/SemaChecking.cpp
>>     cfe/trunk/test/Sema/format-strings-fixit.c
>>
>> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=263299&r1=263298&r2=263299&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Mar 11 15:55:37 2016
>> @@ -3621,20 +3621,32 @@ bool Sema::CheckFormatArguments(ArrayRef
>>    // format is either NSString or CFString. This is a hack to prevent
>>    // diag when using the NSLocalizedString and CFCopyLocalizedString
>> macros
>>    // which are usually used in place of NS and CF string literals.
>> -  if (Type == FST_NSString &&
>> -      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
>> +  SourceLocation FormatLoc = Args[format_idx]->getLocStart();
>> +  if (Type == FST_NSString && SourceMgr.isInSystemMacro(FormatLoc))
>>      return false;
>>
>>    // If there are no arguments specified, warn with -Wformat-security,
>> otherwise
>>    // warn only with -Wformat-nonliteral.
>> -  if (Args.size() == firstDataArg)
>> -    Diag(Args[format_idx]->getLocStart(),
>> -         diag::warn_format_nonliteral_noargs)
>> +  if (Args.size() == firstDataArg) {
>> +    const SemaDiagnosticBuilder &D =
>> +      Diag(FormatLoc, diag::warn_format_nonliteral_noargs);
>> +    switch (Type) {
>> +    default:
>> +      D << OrigFormatExpr->getSourceRange();
>> +      break;
>> +    case FST_Kprintf:
>> +    case FST_FreeBSDKPrintf:
>> +    case FST_Printf:
>> +      D << FixItHint::CreateInsertion(FormatLoc, "\"%s\", ");
>> +      break;
>> +    case FST_NSString:
>> +      D << FixItHint::CreateInsertion(FormatLoc, "@\"%@\", ");
>> +      break;
>> +    }
>> +  } else {
>> +    Diag(FormatLoc, diag::warn_format_nonliteral)
>>        << OrigFormatExpr->getSourceRange();
>> -  else
>> -    Diag(Args[format_idx]->getLocStart(),
>> -         diag::warn_format_nonliteral)
>> -           << OrigFormatExpr->getSourceRange();
>> +  }
>>    return false;
>>  }
>>
>>
>> Modified: cfe/trunk/test/Sema/format-strings-fixit.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/format-strings-fixit.c?rev=263299&r1=263298&r2=263299&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/format-strings-fixit.c (original)
>> +++ cfe/trunk/test/Sema/format-strings-fixit.c Fri Mar 11 15:55:37 2016
>> @@ -16,6 +16,8 @@ typedef __UINTMAX_TYPE__ uintmax_t;
>>  typedef __PTRDIFF_TYPE__ ptrdiff_t;
>>  typedef __WCHAR_TYPE__ wchar_t;
>>
>> +extern const char *NonliteralString;
>> +
>>  void test() {
>>    // Basic types
>>    printf("%s", (int) 123);
>> @@ -94,6 +96,9 @@ void test() {
>>    printf("%G", (long double) 42);
>>    printf("%a", (long double) 42);
>>    printf("%A", (long double) 42);
>> +
>> +  // nonliteral format
>> +  printf(NonliteralString);
>>  }
>>
>>  int scanf(char const *, ...);
>> @@ -218,6 +223,7 @@ void test2(int intSAParm[static 2]) {
>>  // CHECK: printf("%LG", (long double) 42);
>>  // CHECK: printf("%La", (long double) 42);
>>  // CHECK: printf("%LA", (long double) 42);
>> +// CHECK: printf("%s", NonliteralString);
>>
>>  // CHECK: scanf("%99s", str);
>>  // CHECK: scanf("%s", vstr);
>>
>> Added: cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m?rev=263299&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m (added)
>> +++ cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m Fri Mar 11
>> 15:55:37 2016
>> @@ -0,0 +1,31 @@
>> +// RUN: cp %s %t
>> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin
>> -Wno-objc-root-class -pedantic -Wall -fixit %t
>> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin
>> -Wno-objc-root-class -fsyntax-only -pedantic -Wall -Werror %t
>> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin
>> -Wno-objc-root-class -E -o - %t | FileCheck %s
>> +
>> +typedef signed char BOOL;
>> +typedef unsigned int NSUInteger;
>> +typedef struct _NSZone NSZone;
>> + at class NSCoder, NSString, NSEnumerator;
>> + at protocol NSObject  - (BOOL)isEqual:(id)object; @end
>> + at protocol NSCopying  - (id)copyWithZone:(NSZone *)zone; @end
>> + at protocol NSMutableCopying  - (id)mutableCopyWithZone:(NSZone *)zone;
>> @end
>> + at protocol NSCoding  - (void)encodeWithCoder:(NSCoder *)aCoder; @end
>> + at interface NSObject <NSObject> {} @end
>> + at interface NSString : NSObject <NSCopying, NSMutableCopying, NSCoding>
>> - (NSUInteger)length; @end
>> +extern void NSLog(NSString *format, ...);
>> +
>> +/* This is a test of the various code modification hints that are
>> +   provided as part of warning or extension diagnostics. All of the
>> +   warnings will be fixed by -fixit, and the resulting file should
>> +   compile cleanly with -Werror -pedantic. */
>> +
>> +extern NSString *NonliteralString;
>> +
>> +void test() {
>> +  // nonliteral format
>> +  NSLog(NonliteralString);
>> +}
>> +
>> +// Validate the fixes.
>> +// CHECK: NSLog(@"%@", NonliteralString);
>>
>>
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>> cfe-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>
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