[ClangImporter] Fix (lack of) name importing for ObjC ivars #40114
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When swiftlang#39664 moved the logic for generating anonymous fields' names from ImportDecl to ImportName, it inadvertently replaced a check that the decl was *precisely* `clang::FieldDecl` with a check that it was `FieldDecl` *or a subclass*. This could cause a crash when it tried to call `FieldDecl::getFieldIndex()`, which doesn't work properly on instance variables even though `ObjCIvarDecl` is a subclass of `FieldDecl`. The easiest way to reproduce this is to use a bit field in a class's instance variables, since clang inserts an anonymous instance variable after it for padding. This commit adds a test of a bit field instance variable and fixes the bug. It also adds a PrettyStackTrace frame in the Swift lookup table preparation code, which should make other bugs like this easier to diagnose. Fixes rdar://85173321.
zoecarver
approved these changes
Nov 10, 2021
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When #39664 moved the logic for generating anonymous fields' names from ImportDecl to ImportName, it inadvertently replaced a check that the decl was precisely
clang::FieldDeclwith a check that it wasFieldDeclor a subclass. This could cause a crash when it tried to callFieldDecl::getFieldIndex(), which doesn't work properly on instance variables even thoughObjCIvarDeclis a subclass ofFieldDecl. The easiest way to reproduce this is to use a bit field in a class's instance variables, since clang inserts an anonymous instance variable after it for padding.This commit adds a test of a bit field instance variable and fixes the bug. It also adds a PrettyStackTrace frame in the Swift lookup table preparation code, which should make other bugs like this easier to diagnose.
Fixes rdar://85173321.