Introduce "generator expression" syntax to custom commands (#11209)

Evaluate in the COMMAND arguments of custom commands the generator
expression syntax introduced in commit d2e1f2b4 (Introduce "generator
expressions" to add_test, 2009-08-11).  These expressions have a syntax
like $<TARGET_FILE:mytarget> and are evaluated during build system
generation.  This syntax allows per-configuration target output files to
be referenced in custom command lines.

Source/cmAddCustomCommandCommand.h

@@ -13,6 +13,7 @@
 #define cmAddCustomCommandCommand_h
 
 #include "cmCommand.h"
+#include "cmDocumentGeneratorExpressions.h"
 
 /** \class cmAddCustomCommandCommand
  * \brief 
@@ -146,8 +147,15 @@ public:
       "target-level dependency will be added so that the executable target "
       "will be built before any target using this custom command.  However "
       "this does NOT add a file-level dependency that would cause the "
-      "custom command to re-run whenever the executable is recompiled.\n"
+      "custom command to re-run whenever the executable is recompiled."
-
+      "\n"
+      "Arguments to COMMAND may use \"generator expressions\" with the "
+      "syntax \"$<...>\".  "
+      CM_DOCUMENT_COMMAND_GENERATOR_EXPRESSIONS
+      "References to target names in generator expressions imply "
+      "target-level dependencies, but NOT file-level dependencies.  "
+      "List target names with the DEPENDS option to add file dependencies."
+      "\n"
       "The DEPENDS option specifies files on which the command depends.  "
       "If any dependency is an OUTPUT of another custom command in the "
       "same directory (CMakeLists.txt file) CMake automatically brings the "

Source/cmCustomCommandGenerator.cxx

@@ -14,15 +14,23 @@
 #include "cmMakefile.h"
 #include "cmCustomCommand.h"
 #include "cmLocalGenerator.h"
+#include "cmGeneratorExpression.h"
 
 //----------------------------------------------------------------------------
 cmCustomCommandGenerator::cmCustomCommandGenerator(
   cmCustomCommand const& cc, const char* config, cmMakefile* mf):
   CC(cc), Config(config), Makefile(mf), LG(mf->GetLocalGenerator()),
-  OldStyle(cc.GetEscapeOldStyle()), MakeVars(cc.GetEscapeAllowMakeVars())
+  OldStyle(cc.GetEscapeOldStyle()), MakeVars(cc.GetEscapeAllowMakeVars()),
+  GE(new cmGeneratorExpression(mf, config, cc.GetBacktrace()))
 {
 }
 
+//----------------------------------------------------------------------------
+cmCustomCommandGenerator::~cmCustomCommandGenerator()
+{
+  delete this->GE;
+}
+
 //----------------------------------------------------------------------------
 unsigned int cmCustomCommandGenerator::GetNumberOfCommands() const
 {
@@ -39,7 +47,7 @@ std::string cmCustomCommandGenerator::GetCommand(unsigned int c) const
     {
     return target->GetLocation(this->Config);
     }
-  return argv0;
+  return this->GE->Process(argv0);
 }
 
 //----------------------------------------------------------------------------
@@ -50,7 +58,7 @@ cmCustomCommandGenerator
   cmCustomCommandLine const& commandLine = this->CC.GetCommandLines()[c];
   for(unsigned int j=1;j < commandLine.size(); ++j)
     {
-    std::string const& arg = commandLine[j];
+    std::string arg = this->GE->Process(commandLine[j]);
     cmd += " ";
     if(this->OldStyle)
       {

Source/cmCustomCommandGenerator.h

@@ -17,6 +17,7 @@
 class cmCustomCommand;
 class cmMakefile;
 class cmLocalGenerator;
+class cmGeneratorExpression;
 
 class cmCustomCommandGenerator
 {
@@ -26,9 +27,11 @@ class cmCustomCommandGenerator
   cmLocalGenerator* LG;
   bool OldStyle;
   bool MakeVars;
+  cmGeneratorExpression* GE;
 public:
   cmCustomCommandGenerator(cmCustomCommand const& cc, const char* config,
                            cmMakefile* mf);
+  ~cmCustomCommandGenerator();
   unsigned int GetNumberOfCommands() const;
   std::string GetCommand(unsigned int c) const;
   void AppendArguments(unsigned int c, std::string& cmd) const;

Source/cmTarget.cxx

@@ -17,6 +17,7 @@
 #include "cmGlobalGenerator.h"
 #include "cmComputeLinkInformation.h"
 #include "cmListFileCache.h"
+#include "cmGeneratorExpression.h"
 #include <cmsys/RegularExpression.hxx>
 #include <map>
 #include <set>
@@ -1402,6 +1403,7 @@ cmTargetTraceDependencies
 {
   // Transform command names that reference targets built in this
   // project to corresponding target-level dependencies.
+  cmGeneratorExpression ge(this->Makefile, 0, cc.GetBacktrace(), true);
   for(cmCustomCommandLines::const_iterator cit = cc.GetCommandLines().begin();
       cit != cc.GetCommandLines().end(); ++cit)
     {
@@ -1418,6 +1420,21 @@ cmTargetTraceDependencies
         this->Target->AddUtility(command.c_str());
         }
       }
+
+    // Check for target references in generator expressions.
+    for(cmCustomCommandLine::const_iterator cli = cit->begin();
+        cli != cit->end(); ++cli)
+      {
+      ge.Process(*cli);
+      }
+    }
+
+  // Add target-level dependencies referenced by generator expressions.
+  std::set<cmTarget*> targets = ge.GetTargets();
+  for(std::set<cmTarget*>::iterator ti = targets.begin();
+      ti != targets.end(); ++ti)
+    {
+    this->Target->AddUtility((*ti)->GetName());
     }
 
   // Queue the custom command dependencies.

Tests/CustomCommand/CMakeLists.txt

@@ -423,3 +423,15 @@ ADD_CUSTOM_TARGET(DifferentName ALL
   )
 #
 # </SameNameTest>
+
+# Per-config target name and generator expressions.
+ADD_SUBDIRECTORY(${CMAKE_CURRENT_SOURCE_DIR}/../PerConfig PerConfig)
+ADD_CUSTOM_COMMAND(
+  OUTPUT perconfig.out
+  COMMAND ${PerConfig_COMMAND}
+  DEPENDS ${PerConfig_DEPENDS}
+  VERBATIM
+  )
+ADD_CUSTOM_TARGET(perconfig_target ALL
+  COMMAND ${CMAKE_COMMAND} -E echo "perconfig=$<TARGET_FILE:perconfig>" "config=$<CONFIGURATION>"
+  DEPENDS perconfig.out)

Tests/PerConfig/CMakeLists.txt

@@ -31,3 +31,4 @@ SET(PerConfig_COMMAND
     -P ${PerConfig_SOURCE_DIR}/perconfig.cmake
     )
 SET(PerConfig_COMMAND "${PerConfig_COMMAND}" PARENT_SCOPE)
+SET(PerConfig_DEPENDS ${PerConfig_SOURCE_DIR}/perconfig.cmake perconfig pcStatic pcShared)

Tests/PerConfig/perconfig.cmake

@@ -10,7 +10,7 @@ foreach(v
     pcShared_linker_file
     pcShared_soname_file
     )
-  message("${v}=${${v}}")
+  message(STATUS "${v}=${${v}}")
 endforeach()
 
 # Verify that file names match as expected.