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91 lines
3.3 KiB
91 lines
3.3 KiB
From c081bf4098c729afacf20303cc9df62bf13c3362 Mon Sep 17 00:00:00 2001
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From: serge-sans-paille <sguelton@redhat.com>
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Date: Sat, 18 Jun 2022 13:48:41 +0200
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Subject: [PATCH] [clang] Enforce instantiation of constexpr template functions
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during non-constexpr evaluation
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Otherwise these functions are not instantiated and we end up with an undefined
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symbol.
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Fix #55560
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Differential Revision: https://reviews.llvm.org/D128119
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---
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clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 5 +++--
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.../CodeGenCXX/constexpr-late-instantiation.cpp | 17 +++++++++++++++++
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.../SemaCXX/constexpr-late-instantiation.cpp | 15 +++++++++++++++
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3 files changed, 35 insertions(+), 2 deletions(-)
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create mode 100644 clang/test/CodeGenCXX/constexpr-late-instantiation.cpp
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create mode 100644 clang/test/SemaCXX/constexpr-late-instantiation.cpp
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diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
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index 467372c71496..293782822e83 100644
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--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
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+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
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@@ -4826,7 +4826,8 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
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/*Complain*/DefinitionRequired)) {
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if (DefinitionRequired)
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Function->setInvalidDecl();
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- else if (TSK == TSK_ExplicitInstantiationDefinition) {
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+ else if (TSK == TSK_ExplicitInstantiationDefinition ||
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+ (Function->isConstexpr() && !Recursive)) {
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// Try again at the end of the translation unit (at which point a
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// definition will be required).
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assert(!Recursive);
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@@ -4841,7 +4842,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
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Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
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if (getLangOpts().CPlusPlus11)
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Diag(PointOfInstantiation, diag::note_inst_declaration_hint)
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- << Function;
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+ << Function;
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}
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}
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diff --git a/clang/test/CodeGenCXX/constexpr-late-instantiation.cpp b/clang/test/CodeGenCXX/constexpr-late-instantiation.cpp
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new file mode 100644
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index 000000000000..1c8eef73f2dd
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--- /dev/null
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+++ b/clang/test/CodeGenCXX/constexpr-late-instantiation.cpp
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@@ -0,0 +1,17 @@
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+// Make sure foo is instantiated and we don't get a link error
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+// RUN: %clang_cc1 -S -emit-llvm -triple %itanium_abi_triple %s -o- | FileCheck %s
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+
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+template <typename T>
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+constexpr T foo(T a);
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+
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+// CHECK-LABEL: define {{.*}} @main
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+int main() {
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+ // CHECK: call {{.*}} @_Z3fooIiET_S0_
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+ int k = foo<int>(5);
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+}
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+// CHECK: }
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+
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+template <typename T>
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+constexpr T foo(T a) {
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+ return a;
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+}
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diff --git a/clang/test/SemaCXX/constexpr-late-instantiation.cpp b/clang/test/SemaCXX/constexpr-late-instantiation.cpp
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new file mode 100644
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index 000000000000..ec8e071217c1
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--- /dev/null
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+++ b/clang/test/SemaCXX/constexpr-late-instantiation.cpp
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@@ -0,0 +1,15 @@
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+// RUN: %clang_cc1 %s -fsyntax-only -verify
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+
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+template <typename T>
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+constexpr T foo(T a); // expected-note {{declared here}}
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+
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+int main() {
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+ int k = foo<int>(5); // Ok
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+ constexpr int j = // expected-error {{constexpr variable 'j' must be initialized by a constant expression}}
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+ foo<int>(5); // expected-note {{undefined function 'foo<int>' cannot be used in a constant expression}}
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+}
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+
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+template <typename T>
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+constexpr T foo(T a) {
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+ return a;
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+}
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--
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2.38.1
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