Fix fragile List::binarySearch() usage#10047
Fix fragile List::binarySearch() usage#10047cmarcelo wants to merge 1 commit intoshader-slang:masterfrom
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This patch was motivated by #10048. |
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Pull request overview
This PR fixes fragile usage of List::binarySearch() in the semantic checking of generic type equality constraints. The old code incorrectly used binarySearch() with pointer comparison on a member list ordered by declaration position, which only worked by chance because the allocator happened to produce pointers in declaration order. This is replaced with the existing helper function _compareDeclsInCommonParentByOrderOfDeclaration() that properly compares declarations by their position in the parent container, following the guidance from PR #7242 to use mediated access to ContainerDecl members.
Changes:
- Replaced fragile
binarySearch()usage with proper declaration order comparison helper function - Added forward declaration for
_compareDeclsInCommonParentByOrderOfDeclaration()
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Verify each finding against the current code and only fix it if needed.
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In `@source/slang/slang-check-decl.cpp`:
- Around line 3581-3582: The subtraction using auto subIndex =
ancestor->getMembers().indexOf(subAncestor) and auto supIndex =
ancestor->getMembers().indexOf(supAncestor) must guard against indexOf returning
-1; if either subIndex or supIndex is -1, avoid using int(supIndex - subIndex)
and instead fall back to the existing compareDecls(...) logic (or assert/handle
error) to determine ordering. Update the code around where subIndex/supIndex are
computed so you check (subIndex < 0 || supIndex < 0) and call compareDecls(…)
when invalid, otherwise keep the current subtraction path.
| auto subIndex = ancestor->getMembers().indexOf(subAncestor); | ||
| auto supIndex = ancestor->getMembers().indexOf(supAncestor); |
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Add guards against indexOf returning -1 to prevent incorrect index subtraction.
At lines 3581-3582, indexOf can return -1 if subAncestor or supAncestor is not present in ancestor->getMembers(). The direct subtraction int(supIndex - subIndex) then produces incorrect ordering: (-1 - 0 = -1), (0 - (-1) = 1), or (-1 - (-1) = 0), with the zero case silently triggering the diagnostic at line 3593. Check both indices and either assert they are valid or fall back to compareDecls.
Suggested guard
auto subIndex = ancestor->getMembers().indexOf(subAncestor);
auto supIndex = ancestor->getMembers().indexOf(supAncestor);
+ if (subIndex == Index(-1) || supIndex == Index(-1))
+ return compareDecls(subAncestor, supAncestor);
return int(supIndex - subIndex);📝 Committable suggestion
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| auto subIndex = ancestor->getMembers().indexOf(subAncestor); | |
| auto supIndex = ancestor->getMembers().indexOf(supAncestor); | |
| auto subIndex = ancestor->getMembers().indexOf(subAncestor); | |
| auto supIndex = ancestor->getMembers().indexOf(supAncestor); | |
| if (subIndex == Index(-1) || supIndex == Index(-1)) | |
| return compareDecls(subAncestor, supAncestor); | |
| return int(supIndex - subIndex); |
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@source/slang/slang-check-decl.cpp` around lines 3581 - 3582, The subtraction
using auto subIndex = ancestor->getMembers().indexOf(subAncestor) and auto
supIndex = ancestor->getMembers().indexOf(supAncestor) must guard against
indexOf returning -1; if either subIndex or supIndex is -1, avoid using
int(supIndex - subIndex) and instead fall back to the existing compareDecls(...)
logic (or assert/handle error) to determine ordering. Update the code around
where subIndex/supIndex are computed so you check (subIndex < 0 || supIndex < 0)
and call compareDecls(…) when invalid, otherwise keep the current subtraction
path.
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Would someone help verify if it is applicable, is it a valid concern? My own understanding here is that we expect both to be found.
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The binarySearch() was comparing pointer addresses on the member list that is ordered by the declaration position. That may not necessarily work unless is guaranteed that the allocator produces pointers in declaration order and they are not reordered. Use indexOf() instead. See bfae49d ("Mediate access to ContainerDecl members (shader-slang#7242)") for context.
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The binarySearch() was comparing pointer addresses on the member list
that is ordered by the declaration position. That may not necessarily
work unless is guaranteed that the allocator produces pointers in
declaration order and they are not reordered. Use indexOf() instead.
See bfae49d ("Mediate access to ContainerDecl members (#7242)") for context.