[llvm-branch-commits] [clang] [Clang] [C++26] Expansion Statements (Part 2: Parsing and Parser Tests) (PR #169681)

[via llvm-branch-commits]

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+//===-- SemaExpand.cpp - Semantic Analysis for Expansion Statements--------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements semantic analysis for C++26 expansion statements,
+//  aka 'template for'.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/EnterExpressionEvaluationContext.h"
+#include "clang/Sema/Lookup.h"
+#include "clang/Sema/Overload.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/Template.h"
+
+using namespace clang;
+using namespace sema;
+
+
+CXXExpansionStmtDecl *
+Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth,
+                                SourceLocation TemplateKWLoc) {
+  // Create a template parameter '__N'. This will be used to denote the index
+  // of the element that we're instantiating. CWG 3044 requires this type to
+  // be 'ptrdiff_t' for iterating expansion statements, so use that in all
+  // cases.
+  IdentifierInfo *ParmName = &Context.Idents.get("__N");
+  QualType ParmTy = Context.getPointerDiffType();
+  TypeSourceInfo *ParmTI =
+      Context.getTrivialTypeSourceInfo(ParmTy, TemplateKWLoc);
+
+  auto *TParam = NonTypeTemplateParmDecl::Create(
+      Context, Context.getTranslationUnitDecl(), TemplateKWLoc, TemplateKWLoc,
+      TemplateDepth, /*Position=*/0, ParmName, ParmTy, /*ParameterPack=*/false,
+      ParmTI);
+
+  return BuildCXXExpansionStmtDecl(CurContext, TemplateKWLoc, TParam);
+}
+
+CXXExpansionStmtDecl *
+Sema::BuildCXXExpansionStmtDecl(DeclContext *Ctx, SourceLocation TemplateKWLoc,
+                                NonTypeTemplateParmDecl *NTTP) {
+  auto *TParamList = TemplateParameterList::Create(
+      Context, TemplateKWLoc, TemplateKWLoc, {NTTP}, TemplateKWLoc,
+      /*RequiresClause=*/nullptr);
+  auto *Result =
+      CXXExpansionStmtDecl::Create(Context, Ctx, TemplateKWLoc, TParamList);
+  Ctx->addDecl(Result);
+  return Result;
+}
+
+ExprResult Sema::ActOnCXXExpansionInitList(MultiExprArg SubExprs,
+                                           SourceLocation LBraceLoc,
+                                           SourceLocation RBraceLoc) {
+  return CXXExpansionInitListExpr::Create(Context, SubExprs, LBraceLoc,
+                                          RBraceLoc);
+}
+
+StmtResult Sema::ActOnCXXExpansionStmtPattern(
+    CXXExpansionStmtDecl *ESD, Stmt *Init, Stmt *ExpansionVarStmt,
+    Expr *ExpansionInitializer, SourceLocation LParenLoc,
+    SourceLocation ColonLoc, SourceLocation RParenLoc,
+    ArrayRef<MaterializeTemporaryExpr *> LifetimeExtendTemps) {
+  Diag(ESD->getLocation(), diag::err_expansion_statements_todo);
+  return StmtError();
+}
+
+StmtResult Sema::FinishCXXExpansionStmt(Stmt *Exp, Stmt *Body) {
+  if (!Exp || !Body)
+    return StmtError();
+
+  llvm_unreachable("TODO");
----------------
Sirraide wrote:

That’s also removed later; basically all the TODOs in the entire patch series are removed at some point (and if they aren’t, it’s because I missed one and we don’t have enough tests, but there _shouldn’t_ be any left by the end)

https://github.com/llvm/llvm-project/pull/169681