[clang] [clang][bytecode] Mark global decls with diagnostics invalid (PR #122895)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/122895

Even if their evaluation succeeds, mark them as invalid. This fixes some long standing differences to the ast walker interpeter.

>From 66c1a54bf96661aa0e5b60cf121b03776a8dcbbe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Tue, 14 Jan 2025 13:16:31 +0100
Subject: [PATCH] [clang][bytecode] Mark global decls with diagnostics invalid

Even if their evaluation succeeds, mark them as invalid. This fixes
some long standing differences to the ast walker interpeter.
---
 clang/lib/AST/ByteCode/EvalEmitter.cpp | 12 ++++++++++++
 clang/test/AST/ByteCode/arrays.cpp     | 15 +++++++--------
 clang/test/AST/ByteCode/cxx23.cpp      |  9 +++------
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/clang/lib/AST/ByteCode/EvalEmitter.cpp b/clang/lib/AST/ByteCode/EvalEmitter.cpp
index 9763fe89b73742..f9220e89abbc85 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.cpp
+++ b/clang/lib/AST/ByteCode/EvalEmitter.cpp
@@ -71,6 +71,18 @@ EvaluationResult EvalEmitter::interpretDecl(const VarDecl *VD,
   if (!this->visitDeclAndReturn(VD, S.inConstantContext()))
     EvalResult.setInvalid();
 
+  // Mark global variables as invalid if any diagnostic was produced.
+  if (S.hasPriorDiagnostic() && Context::shouldBeGloballyIndexed(VD)) {
+    if (auto GlobalIndex = P.getGlobal(VD)) {
+      Block *GlobalBlock = P.getGlobal(*GlobalIndex);
+      GlobalInlineDescriptor &GD =
+          *reinterpret_cast<GlobalInlineDescriptor *>(GlobalBlock->rawData());
+      GD.InitState = GlobalInitState::InitializerFailed;
+      if (GlobalBlock->isInitialized())
+        GlobalBlock->invokeDtor();
+    }
+  }
+
   S.EvaluatingDecl = nullptr;
   updateGlobalTemporaries();
   return std::move(this->EvalResult);
diff --git a/clang/test/AST/ByteCode/arrays.cpp b/clang/test/AST/ByteCode/arrays.cpp
index 4097c65f7c6fba..297894659ff199 100644
--- a/clang/test/AST/ByteCode/arrays.cpp
+++ b/clang/test/AST/ByteCode/arrays.cpp
@@ -402,14 +402,13 @@ namespace NoInitMapLeak {
 
   constexpr int a[] = {1,2,3,4/0,5}; // both-error {{must be initialized by a constant expression}} \
                                      // both-note {{division by zero}} \
-                                     // ref-note {{declared here}}
-
-  /// FIXME: This should fail in the new interpreter as well.
-  constexpr int b = a[0]; // ref-error {{must be initialized by a constant expression}} \
-                          // ref-note {{is not a constant expression}} \
-                          // ref-note {{declared here}}
-  static_assert(b == 1, ""); // ref-error {{not an integral constant expression}} \
-                             // ref-note {{not a constant expression}}
+                                     // both-note {{declared here}}
+
+  constexpr int b = a[0]; // both-error {{must be initialized by a constant expression}} \
+                          // both-note {{is not a constant expression}} \
+                          // both-note {{declared here}}
+  static_assert(b == 1, ""); // both-error {{not an integral constant expression}} \
+                             // both-note {{not a constant expression}}
 
   constexpr int f() { // both-error {{never produces a constant expression}}
     int a[] = {19,2,3/0,4}; // both-note 2{{division by zero}} \
diff --git a/clang/test/AST/ByteCode/cxx23.cpp b/clang/test/AST/ByteCode/cxx23.cpp
index 6a62ac11cde792..5c437c2eef84bf 100644
--- a/clang/test/AST/ByteCode/cxx23.cpp
+++ b/clang/test/AST/ByteCode/cxx23.cpp
@@ -217,16 +217,13 @@ namespace UndefinedThreeWay {
                                                 // all-note {{undefined function 'operator<=>' cannot be used in a constant expression}}
 }
 
-/// FIXME: The new interpreter is missing the "initializer of q is not a constant expression" diagnostics.a
-/// That's because the cast from void* to int* is considered fine, but diagnosed. So we don't consider
-/// q to be uninitialized.
 namespace VoidCast {
   constexpr void* p = nullptr;
   constexpr int* q = static_cast<int*>(p); // all-error {{must be initialized by a constant expression}} \
                                            // all-note {{cast from 'void *' is not allowed in a constant expression}} \
-                                           // ref-note {{declared here}}
-  static_assert(q == nullptr); // ref-error {{not an integral constant expression}} \
-                               // ref-note {{initializer of 'q' is not a constant expression}}
+                                           // all-note {{declared here}}
+  static_assert(q == nullptr); // all-error {{not an integral constant expression}} \
+                               // all-note {{initializer of 'q' is not a constant expression}}
 }
 
 namespace ExplicitLambdaInstancePointer {