[clang] [Clang] CXXConstructExpr may be immediate calls. (PR #82179)

[via cfe-commits]

https://github.com/cor3ntin created https://github.com/llvm/llvm-project/pull/82179

A CXXConstructExpr may refer to an immediate constructor, in which case it should be substituted in the
enclosing default init expression.

Fixes #82154

>From c44bc36631c0b36f4a8e91f50221cc0f6d85038d Mon Sep 17 00:00:00 2001
From: Corentin Jabot <corentinjabot at gmail.com>
Date: Sun, 18 Feb 2024 18:06:14 +0100
Subject: [PATCH] [Clang] CXXConstructExpr may be immediate calls.

A CXXConstructExpr may refer to an immediate constructor,
in which case it should be substituted in the
enclosing default init expression.

Fixes #82154
---
 clang/docs/ReleaseNotes.rst               |  2 ++
 clang/lib/Sema/SemaExpr.cpp               |  6 ++++++
 clang/test/CodeGenCXX/cxx2a-consteval.cpp | 17 +++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 06c7d57d73ca70..45ace4191592d3 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -265,6 +265,8 @@ Bug Fixes to C++ Support
 - No longer reject valid use of the ``_Alignas`` specifier when declaring a
   local variable, which is supported as a C11 extension in C++. Previously, it
   was only accepted at namespace scope but not at local function scope.
+- Clang no longer tries to call consteval constructors at runtime when they appear in a member initializer.
+  (`#782154 <https://github.com/llvm/llvm-project/issues/82154>`_`)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 4049ab3bf6cafb..37a7db889a6eac 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6201,6 +6201,12 @@ struct ImmediateCallVisitor : public RecursiveASTVisitor<ImmediateCallVisitor> {
     return RecursiveASTVisitor<ImmediateCallVisitor>::VisitStmt(E);
   }
 
+  bool VisitCXXConstructExpr(CXXConstructExpr *E) {
+    if (const FunctionDecl *FD = E->getConstructor())
+      HasImmediateCalls |= FD->isImmediateFunction();
+    return RecursiveASTVisitor<ImmediateCallVisitor>::VisitStmt(E);
+  }
+
   // SourceLocExpr are not immediate invocations
   // but CXXDefaultInitExpr/CXXDefaultArgExpr containing a SourceLocExpr
   // need to be rebuilt so that they refer to the correct SourceLocation and
diff --git a/clang/test/CodeGenCXX/cxx2a-consteval.cpp b/clang/test/CodeGenCXX/cxx2a-consteval.cpp
index 06f1d512accec5..075cab58358abf 100644
--- a/clang/test/CodeGenCXX/cxx2a-consteval.cpp
+++ b/clang/test/CodeGenCXX/cxx2a-consteval.cpp
@@ -258,3 +258,20 @@ void void_call() { // EVAL-FN-LABEL: define {{.*}} @_Z9void_call
   void_test();
   // EVAL-FN: {{^}}}
 }
+
+
+namespace GH82154 {
+struct S1 { consteval S1(int) {} };
+struct S3 { constexpr S3(int) {} };
+
+void f() {
+    struct S2 {
+        S1 s = 0;
+        S3 s2 = 0;
+    };
+    S2 s;
+    // EVAL-FN-LABEL: define {{.*}} void @_ZZN7GH821541fEvEN2S2C2Ev
+    // EVAL-FN-NOT: call void @_ZN7GH821542S1C2Ei
+    // EVAL-FN:     call void @_ZN7GH821542S3C2Ei
+}
+}