[5.7][Autolink Extract] Keep a set of seen linker library flags #59034
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Otherwise we can duplicate linker flags across input binaries, which can result in very large linkerr invocation commands. Resolves swiftlang#58380
compnerd
requested changes
May 23, 2022
| LinkerFlags.push_back(Flag.str()); | ||
| for (const auto &Flag : SplitFlags) { | ||
| // If this is a library '-lxxx' flag, only add it if we have not seen it before | ||
| if (Flag.str().rfind("-l", 0) == 0) { |
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Why std::string::rfind over std::string::compare which would be more idiomatic and clearer?
| for (const auto &Flag : SplitFlags) | ||
| LinkerFlags.push_back(Flag.str()); | ||
| for (const auto &Flag : SplitFlags) { | ||
| // If this is a library '-lxxx' flag, only add it if we have not seen it before |
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I worry about this approach because you have to consider the following equivalences:
-l:library.a-static-lrarylib/library.a
and the following:
-l:library.so-shared-lrarylib/liblibrary.so
Furthermore, the order of the libraries is relevant to linking. The conversion to an unordered_set breaks linking semantics - order of library specification on the command line indicates how to resolve symbols. This can change the symbolic resolution.
AnthonyLatsis
added
🍒 release cherry pick
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Otherwise we can duplicate linker flags across input binaries, which can result in very large linkerr invocation commands.
Resolves #58380