Add -fdebug-prefix-map command line argument#5011
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yanok wants to merge 2 commits intoldc-developers:masterfrom
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Add -fdebug-prefix-map command line argument#5011yanok wants to merge 2 commits intoldc-developers:masterfrom
-fdebug-prefix-map command line argument#5011yanok wants to merge 2 commits intoldc-developers:masterfrom
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November 1, 2025 17:34
Try to follow clang, accepting pairs of <old>=<new> paths.
This is required to have reproducible builds without remapping the source code directory to a fixed location (for example in Bazel, where the source code for every build action will end up in a sanbox directory with some hash in the path name). Try to keep the implementation as close as possible to what clang does.
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JohanEngelen
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| std::string DIBuilder::remapDIPath(llvm::StringRef path) { | ||
| for (const auto &[from, to] : opts::debugPrefixMap) { | ||
| if (path.starts_with(from)) { |
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starts_with looks dangerous, what if I map "some/path="other/thing", does that mean that "some/path_more" also matches and is remapped?
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(could be checked in a test case)
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Yes, but this is what clang does. I guess in the most (only?) use cases this is going to be some "root" path, so we don't expect sources from root_some to be passed to the compiler. Cautious people can do some/path/=other/thing/. It's easy to enforce this in the code, but I don't want to diverge from clang...
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Don't forget to add testcase(s) |
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Superseded by #5039; thanks! |
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Debug info stores the path to the directory where the source is located and that causes problem with getting reproducible build results if ran from different work directories.
Traditionally people solve that by controlling the build environment, such that sources are always at the fixed location. But this can sometimes be undesirable (for example with bazel, where each build action runs in a sandbox with a hash in the path name), so clang supports the
-fdebug-prefix-mapoption to control this.This PR implement the same option in LDC.