[clang] Diagnose for implicit boolean conversions in assignments

[PhilippRados]

This is an unfinished implementation of #33528. I have a couple of questions since I'm new to the codebase:

This warning should be issued for both C and C++. For C++ it is pretty straightforward since I can check this when calling PerformImplicitConversion. However this function isn't called in C and right now I issue the warning for C in Sema::ImpCastExprToType, but I don't know if this function might also be called in C++ resulting in the same warning issued twice.
Ideally I would just have to issue this once for both languages but I can't seem to find the correct ImplicitCast function that gets invoked for both langs.

I also found another already existing warning when running the tests (warn_condition_is_assignment) that is similar to this warning but only gets issued on assignments in conditional-expressions, as opposed to all assignment expressions. In C++ this results in the new and old warning both being displayed even though they both suggest the same thing.
How should this be handled? Should I manually check if the broader warning has already been issued and then remove it or maybe just keep the more general warning as they mean the same thing (-Wparentheses)?

Any feedback is appreciated!

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 8129ba6c70aef54d87893adeb34e76f84fa69fe3 b8244b346c7a97c2eb35ccfea23675b8df4f046e --extensions cpp,h -- clang/include/clang/Sema/Sema.h clang/lib/Sema/Sema.cpp clang/lib/Sema/SemaExprCXX.cpp

View the diff from clang-format here.

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index cc9cb173c0..934812dcc0 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -687,13 +687,13 @@ void Sema::diagnoseZeroToNullptrConversion(CastKind Kind, const Expr *E) {
       << FixItHint::CreateReplacement(E->getSourceRange(), "nullptr");
 }
 
-void Sema::DiagnoseImplicitCastBoolAssignment(Expr* E,QualType Ty) {
+void Sema::DiagnoseImplicitCastBoolAssignment(Expr *E, QualType Ty) {
   if (Ty->isBooleanType()) {
-    if (BinaryOperator* Op = dyn_cast<BinaryOperator>(E)) {
+    if (BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
       // should only be issued for regular assignment `=`, not for e.g `+=`
       if (Op->getOpcode() == BO_Assign) {
         SourceLocation Loc = Op->getOperatorLoc();
-        Diag(Loc,diag::warn_parens_bool_assign) << E->getSourceRange();
+        Diag(Loc, diag::warn_parens_bool_assign) << E->getSourceRange();
       }
     }
   }
@@ -773,7 +773,7 @@ ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
     }
   }
 
-  DiagnoseImplicitCastBoolAssignment(E,Ty);
+  DiagnoseImplicitCastBoolAssignment(E, Ty);
 
   if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
     if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 14ca6a7430..1edce04ed7 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -4393,7 +4393,7 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
     FromType = From->getType();
   }
 
-  DiagnoseImplicitCastBoolAssignment(From,ToType);
+  DiagnoseImplicitCastBoolAssignment(From, ToType);
 
   // If we're converting to an atomic type, first convert to the corresponding
   // non-atomic type.

[PhilippRados]

I'm sorry to have notified you all. Instead of rebasing I merged upstream changes which resulted in all these commits being included in the PR.