path: root/lib/Sema/SemaStmt.cpp

//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements semantic analysis for statements.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ASTContext.h"
#include "clang/Basic/TargetInfo.h"
using namespace clang;

Sema::OwningStmtResult Sema::ActOnExprStmt(ExprArg expr) {
  Expr *E = static_cast<Expr*>(expr.release());
  assert(E && "ActOnExprStmt(): missing expression");

  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
  // void expression for its side effects.  Conversion to void allows any
  // operand, even incomplete types.

  // Same thing in for stmt first clause (when expr) and third clause.
  return Owned(static_cast<Stmt*>(E));
}


Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
  return Owned(new (Context) NullStmt(SemiLoc));
}

Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
                                           SourceLocation StartLoc,
                                           SourceLocation EndLoc) {
  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
  
  // If we have an invalid decl, just return an error.
  if (DG.isNull()) return StmtError();
  
  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
}

Action::OwningStmtResult
Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
                        MultiStmtArg elts, bool isStmtExpr) {
  unsigned NumElts = elts.size();
  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
  // If we're in C89 mode, check that we don't have any decls after stmts.  If
  // so, emit an extension diagnostic.
  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
    // Note that __extension__ can be around a decl.
    unsigned i = 0;
    // Skip over all declarations.
    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
      /*empty*/;

    // We found the end of the list or a statement.  Scan for another declstmt.
    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
      /*empty*/;
    
    if (i != NumElts) {
      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
      Diag(D->getLocation(), diag::ext_mixed_decls_code);
    }
  }
  // Warn about unused expressions in statements.
  for (unsigned i = 0; i != NumElts; ++i) {
    Expr *E = dyn_cast<Expr>(Elts[i]);
    if (!E) continue;
    
    // Warn about expressions with unused results if they are non-void and if
    // this not the last stmt in a stmt expr.
    if (E->getType()->isVoidType() || (isStmtExpr && i == NumElts-1))
      continue;
    
    SourceLocation Loc;
    SourceRange R1, R2;
    if (!E->isUnusedResultAWarning(Loc, R1, R2))
      continue;

    Diag(Loc, diag::warn_unused_expr) << R1 << R2;
  }

  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
}

Action::OwningStmtResult
Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
                    SourceLocation DotDotDotLoc, ExprArg rhsval,
                    SourceLocation ColonLoc) {
  assert((lhsval.get() != 0) && "missing expression in case statement");

  // C99 6.8.4.2p3: The expression shall be an integer constant.