VS10: Generate relative source paths when possible (#12570)

Since commit ed0075bd (Use relative paths for custom command inputs,
2011-06-22) CMake generates full paths to source files in VS 10 project
files to avoid trouble with deep source/build tree paths.  However, the VS
10 IDE will not populate the source file property dialog for a file
referenced by full path.  Instead use a relative path when possible.  When
not possible produce a detailed warning explaining the problem and
suggesting use of shorter directory paths.

Source/cmGlobalVisualStudio10Generator.cxx

@@ -13,6 +13,7 @@
 #include "cmGlobalVisualStudio10Generator.h"
 #include "cmLocalVisualStudio10Generator.h"
 #include "cmMakefile.h"
+#include "cmSourceFile.h"
 #include "cmake.h"
 
 
@@ -50,6 +51,38 @@ cmLocalGenerator *cmGlobalVisualStudio10Generator::CreateLocalGenerator()
   return lg;
 }
 
+//----------------------------------------------------------------------------
+void cmGlobalVisualStudio10Generator::Generate()
+{
+  this->LongestSource = LongestSourcePath();
+  this->cmGlobalVisualStudio8Generator::Generate();
+  if(this->LongestSource.Length > 0)
+    {
+    cmMakefile* mf = this->LongestSource.Target->GetMakefile();
+    cmOStringStream e;
+    e <<
+      "The binary and/or source directory paths may be too long to generate "
+      "Visual Studio 10 files for this project.  "
+      "Consider choosing shorter directory names to build this project with "
+      "Visual Studio 10.  "
+      "A more detailed explanation follows."
+      "\n"
+      "There is a bug in the VS 10 IDE that renders property dialog fields "
+      "blank for files referenced by full path in the project file.  "
+      "However, CMake must reference at least one file by full path:\n"
+      "  " << this->LongestSource.SourceFile->GetFullPath() << "\n"
+      "This is because some Visual Studio tools would append the relative "
+      "path to the end of the referencing directory path, as in:\n"
+      "  " << mf->GetCurrentOutputDirectory() << "/"
+      << this->LongestSource.SourceRel << "\n"
+      "and then incorrectly complain that the file does not exist because "
+      "the path length is too long for some internal buffer or API.  "
+      "To avoid this problem CMake must use a full path for this file "
+      "which then triggers the VS 10 property dialog bug.";
+    mf->IssueMessage(cmake::WARNING, e.str().c_str());
+    }
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalVisualStudio10Generator
 ::GetDocumentation(cmDocumentationEntry& entry) const
@@ -230,3 +263,18 @@ cmGlobalVisualStudio10Generator
   ruleFile += ".rule";
   return ruleFile;
 }
+
+//----------------------------------------------------------------------------
+void cmGlobalVisualStudio10Generator::PathTooLong(
+  cmTarget* target, cmSourceFile* sf, std::string const& sfRel)
+{
+  size_t len = (strlen(target->GetMakefile()->GetCurrentOutputDirectory()) +
+                1 + sfRel.length());
+  if(len > this->LongestSource.Length)
+    {
+    this->LongestSource.Length = len;
+    this->LongestSource.Target = target;
+    this->LongestSource.SourceFile = sf;
+    this->LongestSource.SourceRel = sfRel;
+    }
+}

Source/cmGlobalVisualStudio10Generator.h

@@ -46,6 +46,8 @@ public:
   ///! create the correct local generator
   virtual cmLocalGenerator *CreateLocalGenerator();
 
+  virtual void Generate();
+
   /**
    * Try to determine system infomation such as shared library
    * extension, pthreads, byte order etc.  
@@ -79,10 +81,22 @@ public:
   /** Generate an <output>.rule file path for a given command output.  */
   virtual std::string GenerateRuleFile(std::string const& output) const;
 
+  void PathTooLong(cmTarget* target, cmSourceFile* sf,
+                   std::string const& sfRel);
 protected:
   virtual const char* GetIDEVersion() { return "10.0"; }
 
   std::string PlatformToolset;
   bool ExpressEdition;
+private:
+  struct LongestSourcePath
+  {
+    LongestSourcePath(): Length(0), Target(0), SourceFile(0) {}
+    size_t Length;
+    cmTarget* Target;
+    cmSourceFile* SourceFile;
+    std::string SourceRel;
+  };
+  LongestSourcePath LongestSource;
 };
 #endif

Source/cmVisualStudio10TargetGenerator.cxx

@@ -765,12 +765,23 @@ void cmVisualStudio10TargetGenerator::WriteSource(
     // Normal path conversion resulted in a full path.  VS 10 (but not 11)
     // refuses to show the property page in the IDE for a source file with a
     // full path (not starting in a '.' or '/' AFAICT).  CMake <= 2.8.4 used a
-    // relative path but to allow deeper build trees now CMake uses a full
+    // relative path but to allow deeper build trees CMake 2.8.[5678] used a
-    // path except for custom commands which work only as relative paths.
+    // full path except for custom commands.  Custom commands do not work
-    if(sf->GetCustomCommand())
+    // without a relative path, but they do not seem to be involved in tools
+    // with the above behavior.  For other sources we now use a relative path
+    // when the combined path will not be too long so property pages appear.
+    std::string sourceRel = this->ConvertPath(sf->GetFullPath(), true);
+    size_t const maxLen = 250;
+    if(sf->GetCustomCommand() ||
+       ((strlen(this->Makefile->GetCurrentOutputDirectory()) + 1 +
+         sourceRel.length()) <= maxLen))
       {
       forceRelative = true;
-      sourceFile = this->ConvertPath(sf->GetFullPath(), forceRelative);
+      sourceFile = sourceRel;
+      }
+    else
+      {
+      this->GlobalGenerator->PathTooLong(this->Target, sf, sourceRel);
       }
     }
   this->ConvertToWindowsSlash(sourceFile);