[Clang][P2996] Implement PCH serialization for ExplDependentCallExpr - #330
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[Clang][P2996] Implement PCH serialization for ExplDependentCallExpr#330ddd2951 wants to merge 1 commit into
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The writer emitted ExplDependentCallExpr records without their operands (TODO left in ASTWriterStmt), and the reader had no construction case for the node, so its Visit method was unreachable. Consuming a PCH containing the node aborted on the record-consumption assertion in assertion builds and segfaulted during constant evaluation in release builds. This was hit by any consteval function in a PCH calling std::meta::access_context::current(). Serialize the wrapped call expression and template depth, add the CreateEmpty construction path in the reader, and add a self-verifying PCH regression test that pins the node with an AST-dump check. Fixes bloomberg#329.
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Issue number of the reported bug or feature request: #329
Describe your changes
ExplDependentCallExpr (the P2996-specific node wrapping calls to functions marked [[clang::instantiation_dependent]], e.g. access_context::current()) had no working PCH round-trip: the writer emitted the record without its operands (
TODO(P2996)in ASTWriterStmt), and the reader had no construction case for the node, so its Visit method was unreachable. Consuming a PCH containing the node aborted on the record-consumption assertion in assertion builds and segfaulted in the constant evaluator in release builds (matching the original report).This implements the missing serialization: an EmptyShell constructor and CreateEmpty for the reader's construction switch, and symmetric write/read of the template depth and wrapped call expression.
Testing performed
clang/test/PCH/expl-dependent-call.cppfails on an unpatchedbuild (record-consumption assertion) and passes with this change. It also
pins the node's presence via
-ast-dump+ FileCheck so it cannotsilently degrade if node-creation conditions change.
generated PCHs on the patched build.
environment, but all 12 fail identically on the unpatched baseline; they
are pre-existing and unrelated to this change.
Additional context
Found while compiling reflection-heavy code through clangd's
precompiled-preamble path; the standalone reproducer in #329 does not
require clangd.
Fixes #329.