[clang][NFC] Simplify SourceLocExpr::EvaluateInContext

[tbaeder]

Summary

Use ASTContext::MakeIntValue and remove the std::tie+lambda weirdness.

[cor3ntin]

I agree, this looks better

clang/lib/AST/Expr.cpp

StringRef SourceLocExpr::getBuiltinStr() const {
   llvm_unreachable("unexpected IdentKind!");
 }
 
 APValue SourceLocExpr::EvaluateInContext(const ASTContext &Ctx,
                                          const Expr *DefaultExpr) const {
   SourceLocation Loc;
   const DeclContext *Context;
 
-  std::tie(Loc,
-           Context) = [&]() -> std::pair<SourceLocation, const DeclContext *> {
-    if (auto *DIE = dyn_cast_or_null<CXXDefaultInitExpr>(DefaultExpr))
-      return {DIE->getUsedLocation(), DIE->getUsedContext()};
-    if (auto *DAE = dyn_cast_or_null<CXXDefaultArgExpr>(DefaultExpr))
-      return {DAE->getUsedLocation(), DAE->getUsedContext()};
-    return {this->getLocation(), this->getParentContext()};
-  }();
+  if (const auto *DIE = dyn_cast_if_present<CXXDefaultInitExpr>(DefaultExpr)) {
+    Loc = DIE->getUsedLocation();
+    Context = DIE->getUsedContext();
+  } else if (const auto *DAE =
+                 dyn_cast_if_present<CXXDefaultArgExpr>(DefaultExpr)) {
+    Loc = DAE->getUsedLocation();
+    Context = DAE->getUsedContext();
+  } else {
+    Loc = getLocation();
+    Context = getParentContext();
+  }
 
   PresumedLoc PLoc = Ctx.getSourceManager().getPresumedLoc(
       Ctx.getSourceManager().getExpansionRange(Loc).getEnd());
 
   auto MakeStringLiteral = [&](StringRef Tmp) {
     using LValuePathEntry = APValue::LValuePathEntry;
     StringLiteral *Res = Ctx.getPredefinedStringLiteralFromCache(Tmp);
     // Decay the string to a pointer to the first character.
case SourceLocExpr::FuncSig: {
     const auto *CurDecl = dyn_cast<Decl>(Context);
     const auto Kind = getIdentKind() == SourceLocExpr::Function
                           ? PredefinedExpr::Function
                           : PredefinedExpr::FuncSig;
     return MakeStringLiteral(
         CurDecl ? PredefinedExpr::ComputeName(Kind, CurDecl) : std::string(""));
   }
   case SourceLocExpr::Line:
-  case SourceLocExpr::Column: {
-    llvm::APSInt IntVal(Ctx.getIntWidth(Ctx.UnsignedIntTy),
-                        /*isUnsigned=*/true);
-    IntVal = getIdentKind() == SourceLocExpr::Line ? PLoc.getLine()
-                                                   : PLoc.getColumn();
-    return APValue(IntVal);
-  }
+    return APValue(Ctx.MakeIntValue(PLoc.getLine(), Ctx.UnsignedIntTy));
+  case SourceLocExpr::Column:
+    return APValue(Ctx.MakeIntValue(PLoc.getColumn(), Ctx.UnsignedIntTy));
   case SourceLocExpr::SourceLocStruct: {
     // Fill in a std::source_location::__impl structure, by creating an
     // artificial file-scoped CompoundLiteralExpr, and returning a pointer to
     // that.
     const CXXRecordDecl *ImplDecl = getType()->getPointeeCXXRecordDecl();
     assert(ImplDecl);
 
     // Construct an APValue for the __impl struct, and get or create a Decl
     // corresponding to that. Note that we've already verified that the shape of
     // the ImplDecl type is as expected.
 
     APValue Value(APValue::UninitStruct(), 0, 4);
-    for (FieldDecl *F : ImplDecl->fields()) {
+    for (const FieldDecl *F : ImplDecl->fields()) {
       StringRef Name = F->getName();
       if (Name == "_M_file_name") {
         SmallString<256> Path(PLoc.getFilename());
         clang::Preprocessor::processPathForFileMacro(Path, Ctx.getLangOpts(),
                                                      Ctx.getTargetInfo());
         Value.getStructField(F->getFieldIndex()) = MakeStringLiteral(Path);
       } else if (Name == "_M_function_name") {
         // Note: this emits the PrettyFunction name -- different than what
         // __builtin_FUNCTION() above returns!
         const auto *CurDecl = dyn_cast<Decl>(Context);
         Value.getStructField(F->getFieldIndex()) = MakeStringLiteral(
             CurDecl && !isa<TranslationUnitDecl>(CurDecl)
                 ? StringRef(PredefinedExpr::ComputeName(
                       PredefinedExpr::PrettyFunction, CurDecl))
                 : "");
       } else if (Name == "_M_line") {
-        QualType Ty = F->getType();
-        llvm::APSInt IntVal(Ctx.getIntWidth(Ty),
-                            Ty->hasUnsignedIntegerRepresentation());
-        IntVal = PLoc.getLine();
+        llvm::APSInt IntVal = Ctx.MakeIntValue(PLoc.getLine(), F->getType());
         Value.getStructField(F->getFieldIndex()) = APValue(IntVal);
       } else if (Name == "_M_column") {
-        QualType Ty = F->getType();
-        llvm::APSInt IntVal(Ctx.getIntWidth(Ty),
-                            Ty->hasUnsignedIntegerRepresentation());
-        IntVal = PLoc.getColumn();
+        llvm::APSInt IntVal = Ctx.MakeIntValue(PLoc.getColumn(), F->getType());
         Value.getStructField(F->getFieldIndex()) = APValue(IntVal);
       }
     }
 
     UnnamedGlobalConstantDecl *GV =
         Ctx.getUnnamedGlobalConstantDecl(getType()->getPointeeType(), Value);
 
     return APValue(GV, CharUnits::Zero(), ArrayRef<APValue::LValuePathEntry>{},