[clang] [Clang][Interp] Fix handling of `DecompositionDecl` (PR #100400)
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Wed Jul 24 08:14:39 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: None (yronglin)
<details>
<summary>Changes</summary>
The following code should be well-formed:
```C++
float decompose_complex(_Complex float cf) {
static _Complex float scf;
auto &[sre, sim] = scf;
// ok, this is references initialized by constant expressions all the way down
static_assert(&sre == &__real scf);
static_assert(&sim == &__imag scf);
auto [re, im] = cf;
return re*re + im*im;
}
```
---
Full diff: https://github.com/llvm/llvm-project/pull/100400.diff
2 Files Affected:
- (modified) clang/lib/AST/Interp/Compiler.cpp (+11-2)
- (modified) clang/test/SemaCXX/cxx1z-decomposition.cpp (+1)
``````````diff
diff --git a/clang/lib/AST/Interp/Compiler.cpp b/clang/lib/AST/Interp/Compiler.cpp
index 0fc93c14131e6..6e2f0dbc39dcf 100644
--- a/clang/lib/AST/Interp/Compiler.cpp
+++ b/clang/lib/AST/Interp/Compiler.cpp
@@ -3593,8 +3593,14 @@ VarCreationState Compiler<Emitter>::visitDecl(const VarDecl *VD) {
if (R.notCreated())
return R;
- if (R)
- return true;
+ if (R) {
+ bool Ok = true;
+ if (const auto *DD = dyn_cast<DecompositionDecl>(VD))
+ for (const auto *BD : DD->bindings())
+ if (const auto *HoldingVar = BD->getHoldingVar())
+ Ok &= this->visitDecl(HoldingVar);
+ return Ok;
+ }
if (!R && Context::shouldBeGloballyIndexed(VD)) {
if (auto GlobalIndex = P.getGlobal(VD)) {
@@ -5234,6 +5240,9 @@ bool Compiler<Emitter>::visitDeclRef(const ValueDecl *D, const Expr *E) {
return false;
};
+ if (isa<DecompositionDecl>(VD))
+ return revisit(VD);
+
// Visit local const variables like normal.
if ((VD->hasGlobalStorage() || VD->isLocalVarDecl() ||
VD->isStaticDataMember()) &&
diff --git a/clang/test/SemaCXX/cxx1z-decomposition.cpp b/clang/test/SemaCXX/cxx1z-decomposition.cpp
index 305a9ac2ebc24..19c730303625e 100644
--- a/clang/test/SemaCXX/cxx1z-decomposition.cpp
+++ b/clang/test/SemaCXX/cxx1z-decomposition.cpp
@@ -1,5 +1,6 @@
// RUN: %clang_cc1 -std=c++17 -Wc++20-extensions -verify=expected %s
// RUN: %clang_cc1 -std=c++20 -Wpre-c++20-compat -verify=expected %s
+// RUN: %clang_cc1 -std=c++20 -Wpre-c++20-compat -fexperimental-new-constant-interpreter -verify=expected %s
void use_from_own_init() {
auto [a] = a; // expected-error {{binding 'a' cannot appear in the initializer of its own decomposition declaration}}
``````````
</details>
https://github.com/llvm/llvm-project/pull/100400
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