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Revert "[Clang] Fix missed initializer instantiation bug for variable templates" (#140930)

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Reverts llvm/llvm-project#138122

The patch causes a regression and prevents compiling valid C++ code. 
The code was accepted by earlier versions of clang and GCC. 
See https://github.com/llvm/llvm-project/issues/140773 for details.
This commit is contained in:
Paul Kirth
2025-05-21 20:01:06 -07:00
committed by GitHub
parent 569b6f6dad
commit f0ddadf12c
4 changed files with 3 additions and 30 deletions
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1
clang/docs/ReleaseNotes.rst
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@@ -743,7 +743,6 @@ Bug Fixes to C++ Support
in a ``constexpr`` function. (#GH131432)
- Fixed an incorrect TreeTransform for calls to ``consteval`` functions if a conversion template is present. (#GH137885)
- Clang now emits a warning when class template argument deduction for alias templates is used in C++17. (#GH133806)
- Fix missed initializer instantiation bug for variable templates. (#GH138122)
- Fix a crash when checking the template template parameters of a dependent lambda appearing in an alias declaration.
(#GH136432), (#GH137014), (#GH138018)
- Fixed an assertion when trying to constant-fold various builtins when the argument

6
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
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@@ -6032,11 +6032,11 @@ void Sema::BuildVariableInstantiation(
Context.setStaticLocalNumber(NewVar, Context.getStaticLocalNumber(OldVar));
// Figure out whether to eagerly instantiate the initializer.
if (NewVar->getType()->isUndeducedType()) {
if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
// We're producing a template. Don't instantiate the initializer yet.
} else if (NewVar->getType()->isUndeducedType()) {
// We need the type to complete the declaration of the variable.
InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
} else if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
// We're producing a template. Don't instantiate the initializer yet.
} else if (InstantiatingSpecFromTemplate ||
(OldVar->isInline() && OldVar->isThisDeclarationADefinition() &&
!NewVar->isThisDeclarationADefinition())) {

14
clang/test/CodeGenCXX/cxx1z-inline-variables.cpp
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@@ -1,19 +1,5 @@
// RUN: %clang_cc1 -std=c++1z %s -emit-llvm -o - -triple x86_64-linux-gnu | FileCheck %s
template <typename T> struct InlineAuto {
template <typename G> inline static auto var = 5;
};
int inlineauto = InlineAuto<int>::var<int>;
// CHECK: @_ZN10InlineAutoIiE3varIiEE = {{.*}}i32 5{{.*}}comdat
//
template <typename> struct PartialInlineAuto {
template <typename, typename> inline static auto var = 6;
template <typename T> inline static auto var<int, T> = 7;
};
int partialinlineauto = PartialInlineAuto<int>::var<int, int>;
// CHECK: @_ZN17PartialInlineAutoIiE3varIiiEE = {{.*}}i32 7{{.*}}comdat
struct Q {
// CHECK: @_ZN1Q1kE = linkonce_odr constant i32 5, comdat
static constexpr int k = 5;

12
clang/test/SemaTemplate/cxx17-inline-variables.cpp
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@@ -27,15 +27,3 @@ template <typename T> constexpr int A<T>::n = sizeof(A) + sizeof(T);
template <typename T> inline constexpr int A<T>::m = sizeof(A) + sizeof(T);
static_assert(A<int>().f() == 5);
static_assert(A<int>().g() == 5);
template <typename T> struct InlineAuto {
template <typename G> inline static auto var = 5;
};
template <typename> struct PartialInlineAuto {
template <typename, typename> inline static auto var = 6;
template <typename T> inline static auto var<int, T> = 7;
};
int inlineauto = InlineAuto<int>::var<int>;
int partialinlineauto = PartialInlineAuto<int>::var<int, int>;