[Clang] Fixes to immediate-escalating functions

[cor3ntin]

• Consider that immediate escalating function can appear at global scope, fixing a crash

• Lambda conversion to function pointer was sometimes not performed in an immediate function context when it should be.

Fixes #82258

[llvmbot]

@llvm/pr-subscribers-clang

Author: cor3ntin (cor3ntin)

Changes

• Consider that immediate escalating function can appear at global scope, fixing a crash

• Lambda conversion to function pointer was sometimes not performed in an immediate function context when it should be.

Fixes #82258

---

Full diff: https://github.com/llvm/llvm-project/pull/82281.diff

4 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+4)
• (modified) clang/include/clang/Sema/Sema.h (+3-1)
• (modified) clang/lib/Sema/SemaExpr.cpp (+2-2)
• (modified) clang/test/SemaCXX/cxx2b-consteval-propagate.cpp (+26)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 649ad655905af2..7524741e8ed0ab 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -267,6 +267,10 @@ Bug Fixes to C++ Support
   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>`_`)
+- Fix crash when using an immediate-escalated function at global scope.
+  (`#82258 <https://github.com/llvm/llvm-project/issues/82258>`_)
+- Correctly immediate-escalate lambda conversion functions.
+  (`#82258 <https://github.com/llvm/llvm-project/issues/82258>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index e9cd42ae777df5..6a71fc9a0bf87c 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1158,7 +1158,9 @@ class Sema final {
       if (FD) {
         FD->setWillHaveBody(true);
         S.ExprEvalContexts.back().InImmediateFunctionContext =
-            FD->isImmediateFunction();
+            FD->isImmediateFunction() ||
+            S.ExprEvalContexts[S.ExprEvalContexts.size() - 2]
+                .isConstantEvaluated();
         S.ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
             S.getLangOpts().CPlusPlus20 && FD->isImmediateEscalating();
       } else
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 37a7db889a6eac..816ee9e281359a 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -18311,7 +18311,6 @@ void Sema::CheckUnusedVolatileAssignment(Expr *E) {
 }
 
 void Sema::MarkExpressionAsImmediateEscalating(Expr *E) {
-  assert(!FunctionScopes.empty() && "Expected a function scope");
   assert(getLangOpts().CPlusPlus20 &&
          ExprEvalContexts.back().InImmediateEscalatingFunctionContext &&
          "Cannot mark an immediate escalating expression outside of an "
@@ -18328,7 +18327,8 @@ void Sema::MarkExpressionAsImmediateEscalating(Expr *E) {
   } else {
     assert(false && "expected an immediately escalating expression");
   }
-  getCurFunction()->FoundImmediateEscalatingExpression = true;
+  if (FunctionScopeInfo *FI = getCurFunction())
+    FI->FoundImmediateEscalatingExpression = true;
 }
 
 ExprResult Sema::CheckForImmediateInvocation(ExprResult E, FunctionDecl *Decl) {
diff --git a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
index 531a6262287335..4a75392045d05a 100644
--- a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
+++ b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
@@ -368,3 +368,29 @@ vector<void> v{};
 // expected-note@-2 {{in call to 'vector()'}}
 
 }
+
+
+namespace GH82258 {
+
+template <class R, class Pred>
+constexpr auto none_of(R&& r, Pred pred) -> bool { return true; }
+
+struct info { int value; };
+consteval auto is_invalid(info i) -> bool { return false; }
+constexpr info types[] = { {1}, {3}, {5}};
+
+static_assert(none_of(
+    types,
+    +[](info i) consteval {
+        return is_invalid(i);
+    }
+));
+
+static_assert(none_of(
+    types,
+    []{
+        return is_invalid;
+    }()
+));
+
+}

[AaronBallman]

LGTM!

[AaronBallman]

Someday... I would like to replace this with a function call so I can stop going "wait, is -2 okay??" each time I see it. ;-)

[steakhal]

I've submitted a PR #82609 to backport this commit to release/18.x as it fixes a crash and would be also important for us downstream.