https://bugs.llvm.org/show_bug.cgi?id=51475
Bug ID: 51475
Summary: lld-macho unconditionally loads all contents of an
archive (unlike ld64)
Product: lld
Version: unspecified
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: MachO
Assignee: unassignedb...@nondot.org
Reporter: v...@google.com
CC: g...@fb.com, jezr...@gmail.com,
llvm-bugs@lists.llvm.org, smee...@fb.com
NOTE: I don't think ld64 is being reasonable here but can anyone please
double-check for me in case I've missed something obvious? :)
Repro:
- Make the following files:
```
echo '#import <Foundation/Foundation.h> \n extern NSString *const
SuperImportantSymbol;' > Constants.h && \
echo '#import "Constants.h" \n NSString *const SuperImportantSymbol =
@"SuperImportant";' > Constants.m && \
echo '#import <Foundation/Foundation.h> \n @interface FooUser : NSObject \n +
(NSString *)fooMeth; \n@end' > FooUser.h && \
echo '#import "FooUser.h" \n #import "Constants.h" \n @implementation FooUser
\n +(NSString *)fooMeth { return SuperImportantSymbol; }\n @end' > FooUser.m
&& \
echo '#import <Foundation/Foundation.h> \n @interface DYNFakeImpl : NSObject \n
+(NSString *)fakeMeth; \n @end' > DYNFakeImpl.h && \
echo '#import "DYNFakeImpl.h" \n NSString *const SuperImportantSymbol = @"FAKE
important"; \n @implementation DYNFakeImpl \n +(NSString *)fakeMeth { return
SuperImportantSymbol; } \n @end' > DYNFakeImpl.m
```
- Compile them
clang -c Constants.m && clang -c FooUser.m && clang -c DYNFakeImpl.m
- Pack them into an archive
llvm-ar r libAll.a Constants.o FooUser.o DYNFakeImpl.o
- Link with l64:
ld -demangle -dynamic -bundle -arch "x86_64" -platform_version macos 10.15
11.0 -syslibroot
"/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk"
-ObjC -lc++ -lobjc -lSystem -framework Foundation -o ld64_out libAll.a
This happily produces ld64_out.
Repeat the link step, but with lld, it'd complain about duplicate symbol:
ld64.lld.darwinnew -demangle -dynamic -bundle -arch "x86_64"
-platform_version macos 10.15 11.0 -syslibroot
"/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk"
-ObjC -lc++ -lobjc -lSystem -framework Foundation -o ld64_out Constants.o
FooUser.o DYNFakeImpl.o
ld64.lld.darwinnew: error: duplicate symbol: _SuperImportantSymbol
>>> defined in Constants.o
>>> defined in DYNFakeImpl.o
It's worth noting that even with ld64, if you replace the archive with the
three .o files, then it'd also complain about duplicate symbols.
Is this something lld-macho wants to imitate?
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