Fix colliding WinEH TypeDescriptors for exceptions with the same TypeInfo_Class name #3614
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…Info_Class name As reported in ldc-developers#3501 (comment). Previously, LDC would simply override an existing TypeDescriptor global with an equivalent definition if assertions were disabled. Use different equivalent TypeDescriptors in this exotic case now, by using proper mangling. [The linker can presumably still fold duplicates via ICF.] Ideally, these descriptors would be truly unique, but WinEH depends on string comparisons to check for matching catch clauses, and currently depends on TypeInfo_Class.name to generate these strings at runtime when throwing an exception, see https://github.com/ldc-developers/druntime/blob/19731a92a97dbe4d7f7a4e15ceaff8444a1f879a/src/ldc/eh_msvc.d#L192-L211. So if those names were fully qualified (`cd->toPrettyChars(*true*)` during ClassInfo generation), we'd be fine, but that'd obviously be a breaking change and diverge from upstream.
Instead of the ClassInfo global, which could theoretically be subject to global variable replacement.
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[Extracted from #3517.]
As reported in #3501 (comment).
Previously, LDC would simply override an existing TypeDescriptor global with an equivalent definition if assertions were disabled.
Use different equivalent TypeDescriptors in this exotic case now, by using proper mangling. [The linker can presumably still fold duplicates via ICF.]
Ideally, these descriptors would be truly unique, but WinEH depends on string comparisons to check for matching catch clauses, and currently depends on
TypeInfo_Class.nameto generate these strings at runtime when throwing an exception, see https://github.com/ldc-developers/druntime/blob/19731a92a97dbe4d7f7a4e15ceaff8444a1f879a/src/ldc/eh_msvc.d#L192-L211.So if those names were fully qualified (
cd->toPrettyChars(*true*)during ClassInfo generation), we'd be fine, but that'd obviously be a breaking change and diverge from upstream.