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Sema: filter out invalid base-specifiers before attaching #147213
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@llvm/pr-subscribers-clang Author: Shashi Shankar (shashi1687) ChangesSummaryBriefly what this PR does, in one or two sentences. MotivationWhy this change is needed. Root Cause AnalysisA very short bulleted “root cause.”
Changes in this PRList the key files and rough diff summary.
Test PlanHow you verified the change.
Full diff: https://github.com/llvm/llvm-project/pull/147213.diff 2 Files Affected:
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index f0247f865ba40..231610241d8ee 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -3031,8 +3031,23 @@ void Sema::ActOnBaseSpecifiers(Decl *ClassDecl,
if (!ClassDecl || Bases.empty())
return;
+ // --- drop any bases already diagnosed invalid ---
+ SmallVector<CXXBaseSpecifier *, 4> ValidBases;
+ ValidBases.reserve(Bases.size());
+ for (auto *BS : Bases)
+ if (BS)
+ ValidBases.push_back(BS);
+ if (ValidBases.empty())
+ return;
+
+ if (ValidBases.empty())
+ return; // nothing valid to attach
+
AdjustDeclIfTemplate(ClassDecl);
- AttachBaseSpecifiers(cast<CXXRecordDecl>(ClassDecl), Bases);
+ // Attach only the valid bases so downstream never ICEs
+ AttachBaseSpecifiers(cast<CXXRecordDecl>(ClassDecl),
+ llvm::MutableArrayRef<CXXBaseSpecifier *>(
+ ValidBases.data(), ValidBases.size()));
}
bool Sema::IsDerivedFrom(SourceLocation Loc, CXXRecordDecl *Derived,
diff --git a/clang/test/SemaCXX/invalid-base-inheritance.cpp b/clang/test/SemaCXX/invalid-base-inheritance.cpp
new file mode 100644
index 0000000000000..e37b77bcd3fea
--- /dev/null
+++ b/clang/test/SemaCXX/invalid-base-inheritance.cpp
@@ -0,0 +1,17 @@
+// Tests that invalid base-specifiers no longer crash the compiler.
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+class X; // forward declaration
+
+class A : X { // incomplete base → error, but no ICE
+ // expected-error@-1 {{base class has incomplete type}}
+};
+
+class Y : int { // base not a class → error, but no ICE
+ // expected-error@-1 {{expected class name}}
+};
+
+class Z : X*, virtual int { // mixed invalid specifiers
+ // expected-error@-2 {{base class has incomplete type}}
+ // expected-error@-1 {{expected class name}}
+};
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ActOnBaseSpecifiers now skips nullptr entries returned for invalid bases, avoiding ICE on invalid inheritance. Added regression test in SemaCXX/invalid-inheritance.cpp. Fixes llvm#147186 Signed-off-by: Shashi Shankar <[email protected]>
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Thanks for working on this
Did you try to use !isUsable
instead of IsInvalid in
ParseBaseSpecifier
? I think that might be a simpler fix.
This change needs a release note.
Please add an entry to clang/docs/ReleaseNotes.rst
in the section the most adapted to the change, and referencing any Github issue this change fixes. Thanks!
Summary
Briefly what this PR does, in one or two sentences.
Motivation
Why this change is needed.
Root Cause Analysis
A very short bulleted “root cause.”
ActOnBaseSpecifier
returnsnullptr
for invalid bases.ActOnBaseSpecifiers
passed all pointers (including null) toAttachBaseSpecifiers
.Fixes #147186