Fix if() command and CMP0012 OLD/NEW behavior

The commit "modified the if command to address bug 9123 some" changed
the if() command behavior with respect to named boolean constants.  It
introduced policy CMP0012 to provide compatibility.  However, it also
changed behavior with respect to numbers (like '2') but did not cover
the change with the policy.  Also, the behavior it created for numbers
is confusing ('2' is false).

This commit teaches if() to recognize numbers again, and treats them
like the C language does in terms of boolean conversion.  We also fix
the CMP0012 check to trigger in all cases where the result of boolean
coersion differs from that produced by CMake 2.6.4.

1 files changed, 93 insertions, 73 deletions

diff --git a/Source/cmIfCommand.cxx b/Source/cmIfCommand.cxx
index 5c8f07a..dfdbc86 100644
--- a/Source/cmIfCommand.cxx
+++ b/Source/cmIfCommand.cxx
@@ -213,84 +213,69 @@ bool cmIfCommand
 namespace
 {
   //=========================================================================
-  // returns true if succesfull, the resulting bool parsed is stored in result
-  bool GetBooleanValue(std::string &newArg,
-                       cmMakefile *makefile,
-                       bool &result,
-                       std::string &errorString,
-                       cmPolicies::PolicyStatus Policy12Status,
-                       cmake::MessageType &status)
+  bool GetBooleanValue(std::string& arg, cmMakefile* mf)
   {
-    if (Policy12Status != cmPolicies::OLD &&
-        Policy12Status != cmPolicies::WARN)
-      {
-      // please note IsOn(var) does not always equal !IsOff(var)
-      // that is why each is called
-      if (cmSystemTools::IsOn(newArg.c_str()))
-        {
-        result = true;
-        return true;
-        }
-      if (cmSystemTools::IsOff(newArg.c_str()))
-        {
-        result = false;
-        return true;
-        }
-      return false;
-      }
-
-    // Old policy is more complex...
-    // 0 and 1 are very common, test for them first quickly
-    if (newArg == "0")
+  // Check basic constants.
+  if (arg == "0")
     {
-      result = false;
-      return true;
+    return false;
     }
-    if (newArg == "1")
+  if (arg == "1")
     {
-      result = true;
-      return true;
+    return true;
     }
 
-    // old behavior is to dereference the var
-    if (Policy12Status == cmPolicies::OLD)
+  // Check named constants.
+  if (cmSystemTools::IsOn(arg.c_str()))
     {
-      return false;
+    return true;
+    }
+  if (cmSystemTools::IsOff(arg.c_str()))
+    {
+    return false;
     }
 
-    // now test for values that may be the name of a variable
-    // warn if used
-    if (cmSystemTools::IsOn(newArg.c_str()))
+  // Check for numbers.
+  if(!arg.empty())
+    {
+    char* end;
+    double d = strtod(arg.c_str(), &end);
+    if(*end == '\0')
       {
-      // only warn if the value would change
-      const char *def = makefile->GetDefinition(newArg.c_str());
-      if (cmSystemTools::IsOff(def))
-        {
-        cmPolicies* policies = makefile->GetPolicies();
-        errorString = "A variable or argument named \""
-          + newArg
-          + "\" appears in a conditional statement.  "
-          + policies->GetPolicyWarning(cmPolicies::CMP0012);
-        status = cmake::AUTHOR_WARNING;
-        }
-      return false;
+      // The whole string is a number.  Use C conversion to bool.
+      return d? true:false;
       }
-    if (cmSystemTools::IsOff(newArg.c_str()))
+    }
+
+  // Check definition.
+  const char* def = mf->GetDefinition(arg.c_str());
+  return !cmSystemTools::IsOff(def);
+  }
+
+  //=========================================================================
+  // Boolean value behavior from CMake 2.6.4 and below.
+  bool GetBooleanValueOld(std::string const& arg, cmMakefile* mf, bool one)
+  {
+  if(one)
+    {
+    // Old IsTrue behavior for single argument.
+    if(arg == "0")
+      { return false; }
+    else if(arg == "1")
+      { return true; }
+    else
+      { return !cmSystemTools::IsOff(mf->GetDefinition(arg.c_str())); }
+    }
+  else
+    {
+    // Old GetVariableOrNumber behavior.
+    const char* def = mf->GetDefinition(arg.c_str());
+    if(!def && atoi(arg.c_str()))
       {
-      // only warn if the value would change
-      const char *def = makefile->GetDefinition(newArg.c_str());
-      if (!cmSystemTools::IsOff(def))
-        {
-        cmPolicies* policies = makefile->GetPolicies();
-        errorString = "A variable or argument named \""
-          + newArg
-          + "\" appears in a conditional statement.  "
-          + policies->GetPolicyWarning(cmPolicies::CMP0012);
-        status = cmake::AUTHOR_WARNING;
-        }
-      return false;
+      def = arg.c_str();
       }
-    return false;
+    return !cmSystemTools::IsOff(def);
+    }
   }
 
   //=========================================================================
@@ -300,16 +285,51 @@ namespace
     cmMakefile *makefile,
     std::string &errorString,
     cmPolicies::PolicyStatus Policy12Status,
-    cmake::MessageType &status)
+    cmake::MessageType &status,
+    bool oneArg = false)
   {
-    bool result = false;
-    if (GetBooleanValue(newArg, makefile, result,
-                        errorString, Policy12Status, status))
+  // Use the policy if it is set.
+  if (Policy12Status == cmPolicies::NEW)
     {
-      return result;
+    return GetBooleanValue(newArg, makefile);
     }
-    const char *def = makefile->GetDefinition(newArg.c_str());
-    return !cmSystemTools::IsOff(def);
+  else if (Policy12Status == cmPolicies::OLD)
+    {
+    return GetBooleanValueOld(newArg, makefile, oneArg);
+    }
+
+  // Check policy only if old and new results differ.
+  bool newResult = GetBooleanValue(newArg, makefile);
+  bool oldResult = GetBooleanValueOld(newArg, makefile, oneArg);
+  if(newResult != oldResult)
+    {
+    switch(Policy12Status)
+      {
+      case cmPolicies::WARN:
+        {
+        cmPolicies* policies = makefile->GetPolicies();
+        errorString = "An argument named \"" + newArg
+          + "\" appears in a conditional statement.  "
+          + policies->GetPolicyWarning(cmPolicies::CMP0012);
+        status = cmake::AUTHOR_WARNING;
+        }
+      case cmPolicies::OLD:
+        return oldResult;
+        break;
+      case cmPolicies::REQUIRED_IF_USED:
+      case cmPolicies::REQUIRED_ALWAYS:
+        {
+        cmPolicies* policies = makefile->GetPolicies();
+        errorString = "An argument named \"" + newArg
+          + "\" appears in a conditional statement.  "
+          + policies->GetRequiredPolicyError(cmPolicies::CMP0012);
+        status = cmake::FATAL_ERROR;
+        }
+      case cmPolicies::NEW:
+        break;
+      }
+    }
+  return newResult;
   }
 
   //=========================================================================
@@ -898,7 +918,7 @@ bool cmIfCommand::IsTrue(const std::vector<std::string> &args,
                                             makefile,
                                             errorString,
                                             Policy12Status,
-                                            status);
+                                            status, true);
 }
 
 //=========================================================================