compilerplugins/clang/store/cascadingassignop.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * Based on LLVM/Clang.
   6  *
   7  * This file is distributed under the University of Illinois Open Source
   8  * License. See LICENSE.TXT for details.
   9  *
  10  */
  11
  12 #include "cascadingassignop.hxx"
  13
  14 /*
  15 This is a compile check.
  16
  17 It checks for complex statements with conditional operators in conditional
  18 operators, which are error prone, e.g.
  19  Thing foo = IsBar() ? ( IsBaz() ? b1 : b2 ) : b3;
  20
  21 However, it finds 556 cases in sw/source alone, thus likely needs some more
  22 restricting, e.g. by checking for multiline conditional operator statements or
  23 a certain length in characters (but that needs the Context/SourceManager, which
  24 I haven't played with yet).
  25 */
  26
  27 // the value is rather arbitrary, but code above this number of stmts begins to
  28 // be smelly
  29 static const int stmtlimit = 20;
  30
  31 namespace loplugin
  32 {
  33
  34 struct WalkCounter
  35 {
  36     int  stmtcount;
  37     bool cascading;
  38     bool conditionals;
  39 };
  40
  41 // Ctor, nothing special, pass the argument(s).
  42 CascadingAssignOp::CascadingAssignOp( const InstantiationData& data )
  43     : FilteringPlugin( data )
  44 {
  45 }
  46
  47 // Perform the actual action.
  48 void CascadingAssignOp::run()
  49 {
  50     // Traverse the whole AST of the translation unit (i.e. examine the whole source file).
  51     // The Clang AST helper class will call VisitReturnStmt for every return statement.
  52     TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
  53 }
  54
  55 void CascadingAssignOp::Walk( const Stmt* stmt, WalkCounter& c )
  56 {
  57     for(Stmt::const_child_iterator it = stmt->child_begin(); it != stmt->child_end(); ++it)
  58     {
  59         ++c.stmtcount;
  60         const BinaryOperator* binop = dyn_cast< BinaryOperator >( *it );
  61         if ( binop )
  62         {
  63             if ( (binop->isAssignmentOp() || binop->isCompoundAssignmentOp()))
  64                 c.cascading = true;
  65             if ( dyn_cast< AbstractConditionalOperator >( binop ) || binop->isLogicalOp())
  66                 c.conditionals = true;
  67         }
  68         Walk(*it, c);
  69     }
  70 }
  71
  72 bool CascadingAssignOp::VisitStmt( const Stmt* stmt )
  73 {
  74     const BinaryOperator* binop = dyn_cast< BinaryOperator >( stmt );
  75     if ( binop && (binop->isAssignmentOp() || binop->isCompoundAssignmentOp()))
  76     {
  77         WalkCounter c = { 0, false, false };
  78         Walk(binop, c);
  79         if(c.cascading && c.conditionals && c.stmtcount >= stmtlimit)
  80         {
  81             std::string msg("cascading assign operator mixing in conditionals, complexity: ");
  82             msg.append(std::to_string(c.stmtcount));
  83             report( DiagnosticsEngine::Warning, msg, binop->getLocStart());
  84         }
  85     }
  86     return true;
  87 }
  88
  89 // Register the plugin action with the LO plugin handling.
  90 static Plugin::Registration< CascadingAssignOp > X( "cascadingassignop" );
  91
  92 } // namespace loplugin
  93
  94 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */