[lldb] [llvm] Add support for using foreign type units in .debug_names. (PR #87740)

[David Blaikie via llvm-commits]

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@@ -0,0 +1,91 @@
+// REQUIRES: lld
+
+// This test will make a type that will be compiled differently into two
+// different .dwo files in a type unit with the same type hash, but with
+// differing contents. I have discovered that the hash for the type unit is
+// simply based off of the typename and doesn't seem to differ when the contents
+// differ, so that will help us test foreign type units in the .debug_names
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dwblaikie wrote:

Rather than the personal statement, could maybe just be explicit:

"Clang's type unit signature is based only on the mangled name of the type, regardless of the contents of the type"

(I can tell you that's how it works - that's how I implemented it - it is a violation of the DWARF spec (the spec says to use a content hash - though that content hash is of the semantic contents, not the syntactic content (eg: if the TU contained a type with a single int member, the spec-compliant hash would be the same whether it was the type DIE followed by the int DIE, or the other way around) - so it would still be the same despite some variations in layout, so the index entries still wouldn't be portable to all matched-hash definitions))

https://github.com/llvm/llvm-project/pull/87740