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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109462] New: [13 Regression] Possible
 miscompilation of clang LocalizationChecker since r13-1938
Date: Mon, 10 Apr 2023 10:32:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109462

            Bug ID: 109462
           Summary: [13 Regression] Possible miscompilation of clang
                    LocalizationChecker since r13-1938
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

Created attachment 54823
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54823&action=3Dedit
LocalizationChecker.ii.xz

As mentioned in (but not reported to us) in
https://github.com/llvm/llvm-project/issues/59227
// clang -cc1 test.m -analyze -setup-static-analyzer
-analyzer-checker=3Doptin.osx.cocoa.localizability.EmptyLocalizationContext=
Checker
#define nil ((id)0)
#define NSLocalizedString(key, comment) [[NSBundle mainBundle]
localizedStringForKey:(key) value:@"" table:nil]
struct CGPoint { double x; double y; };
typedef struct CGPoint CGPoint;
@interface NSObject
+ (id)alloc;
- (id)init;
@end
@class NSDictionary;
@interface NSString : NSObject
- (void)drawAtPoint:(CGPoint)point withAttributes:(NSDictionary *)attrs;
+ (instancetype)localizedStringWithFormat:(NSString *)format, ...;
@end
@interface NSBundle : NSObject
+ (NSBundle *)mainBundle;
- (NSString *)localizedStringForKey:(NSString *)key
                              value:(NSString *)value
                              table:(NSString *)tableName;
@end
@interface LocalizationTestSuite : NSObject
@end
@implementation LocalizationTestSuite
- (void)testNilLocalizationContext {
  NSString *string =3D NSLocalizedString(@"LocalizedString", nil);
}
@end
reports an (expected) warning when
clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp is compiled with
r13-1937 and earlier, while
when compiled with r13-1938 and later the warning is not emitted.
The r13-1938 changes cause differences in
_ZNK5clang13SourceManager16getDecomposedLocENS_14SourceLocationE
and
_ZN12_GLOBAL__N_131EmptyLocalizationContextChecker13MethodCrawler20VisitObj=
CMessageExprEPKN5clang15ObjCMessageExprE
functions and it is the latter that matters for whether the warning is repo=
rted
or not (proved by hand-combining assembly
from the 2 revisions, everything from r13-1937 but the
_ZN12_GLOBAL__N_131EmptyLocalizationContextChecker13MethodCrawler20VisitObj=
CMessageExprEPKN5clang15ObjCMessageExprE
function from r13-1938 doesn't report the warning, everything from r13-1938=
 but
that function from r13-1937 does.
First difference in both functions appears in the dom2 dumps.

Flags used to compile were -fPIC -fno-semantic-interposition
-fvisibility-inlines-hidden -ffunction-sections -fdata-sections -fno-common
-fno-strict-aliasing -O3 -fno-exceptions -funwind-tables -fno-rtti -std=3Dc=
++17
LocalizationChecker.ii=