[PATCH] D105446: [clang] fix constexpr code generation for user conversions.

[Matheus Izvekov via Phabricator via cfe-commits]

mizvekov created this revision.
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When building the member call to a user conversion function during an
implicit cast, the expression was not being checked for immediate
invocation, so we were never adding the ConstantExpr node to AST.

This would cause the call to the user conversion operator to be emitted
even if it was constantexpr evaluated, and this would even trip an
assert when said user conversion was declared consteval:
`Assertion failed: !cast<FunctionDecl>(GD.getDecl())->isConsteval() && 
"consteval function should never be emitted", file 
clang\lib\CodeGen\CodeGenModule.cpp, line 3530`

Fixes PR48855.

Signed-off-by: Matheus Izvekov <mizve...@gmail.com>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105446

Files:
  clang/lib/Sema/SemaExprCXX.cpp
  clang/test/CodeGenCXX/cxx2a-consteval.cpp


Index: clang/test/CodeGenCXX/cxx2a-consteval.cpp
===================================================================
--- clang/test/CodeGenCXX/cxx2a-consteval.cpp
+++ clang/test/CodeGenCXX/cxx2a-consteval.cpp
@@ -210,3 +210,15 @@
   AggCtor C(i);
   return C.a + C.b;
 }
+
+struct UserConv {
+  consteval operator int() const noexcept { return 42; }
+};
+
+// EVAL-FN-LABEL: @_Z13test_UserConvv(
+// EVAL-FN-NEXT:  entry:
+// EVAL-FN-NEXT:    ret i32 42
+//
+int test_UserConv() {
+  return UserConv();
+}
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -7786,7 +7786,8 @@
                         Method->getType()->castAs<FunctionProtoType>()))
     return ExprError();
 
-  return CE;
+  return CheckForImmediateInvocation(MaybeBindToTemporary(CE),
+                                     CE->getMethodDecl());
 }
 
 ExprResult Sema::BuildCXXNoexceptExpr(SourceLocation KeyLoc, Expr *Operand,



Index: clang/test/CodeGenCXX/cxx2a-consteval.cpp
===================================================================
--- clang/test/CodeGenCXX/cxx2a-consteval.cpp
+++ clang/test/CodeGenCXX/cxx2a-consteval.cpp
@@ -210,3 +210,15 @@
   AggCtor C(i);
   return C.a + C.b;
 }
+
+struct UserConv {
+  consteval operator int() const noexcept { return 42; }
+};
+
+// EVAL-FN-LABEL: @_Z13test_UserConvv(
+// EVAL-FN-NEXT:  entry:
+// EVAL-FN-NEXT:    ret i32 42
+//
+int test_UserConv() {
+  return UserConv();
+}
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -7786,7 +7786,8 @@
                         Method->getType()->castAs<FunctionProtoType>()))
     return ExprError();
 
-  return CE;
+  return CheckForImmediateInvocation(MaybeBindToTemporary(CE),
+                                     CE->getMethodDecl());
 }
 
 ExprResult Sema::BuildCXXNoexceptExpr(SourceLocation KeyLoc, Expr *Operand,

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