cmake: add --trace-expand option

The --trace option is helpful, but sometimes, what you're looking for is
deep under many layers of function calls and figuring out what instance
of the function call you're looking at is tedious to determine (usually
involving patching and message()). Instead, add a --trace-expand option
to trace while expanding commands into what CMake actually sees.

Help/manual/cmake.1.rst

@@ -113,14 +113,18 @@ Options
 ``--debug-output``
  Put cmake in a debug mode.
 
- Print extra stuff during the cmake run like stack traces with
+ Print extra information during the cmake run like stack traces with
  message(send_error ) calls.
 
 ``--trace``
  Put cmake in trace mode.
 
- Print a trace of all calls made and from where with
+ Print a trace of all calls made and from where.
- message(send_error ) calls.
+
+``--trace-expand``
+ Put cmake in trace mode.
+
+ Like ``--trace``, but with variables expanded.
 
 ``--warn-uninitialized``
  Warn about uninitialized values.

Help/release/dev/trace-expand.rst

@@ -0,0 +1,5 @@
+trace-expand
+------------
+
+* Add ``--trace-expand`` argument to CMake. Acts like ``--trace``, but expands
+  variable references in the output.

Help/variable/CMAKE_POLICY_WARNING_CMPNNNN.rst

@@ -17,5 +17,5 @@ warn by default:
 This variable should not be set by a project in CMake code.  Project
 developers running CMake may set this variable in their cache to
 enable the warning (e.g. ``-DCMAKE_POLICY_WARNING_CMP<NNNN>=ON``).
-Alternatively, running :manual:`cmake(1)` with the ``--debug-output``
+Alternatively, running :manual:`cmake(1)` with the ``--debug-output``,
-or ``--trace`` option will also enable the warning.
+``--trace``, or ``--trace-expand`` option will also enable the warning.

Source/cmMakefile.cxx

@@ -307,10 +307,21 @@ void cmMakefile::PrintCommandTrace(const cmListFileFunction& lff) const
   std::ostringstream msg;
   msg << this->GetExecutionFilePath() << "(" << lff.Line << "):  ";
   msg << lff.Name << "(";
+  bool expand = this->GetCMakeInstance()->GetTraceExpand();
+  std::string temp;
   for(std::vector<cmListFileArgument>::const_iterator i =
         lff.Arguments.begin(); i != lff.Arguments.end(); ++i)
     {
-    msg << i->Value;
+    if (expand)
+      {
+      temp = i->Value;
+      this->ExpandVariablesInString(temp);
+      msg << temp;
+      }
+    else
+      {
+      msg << i->Value;
+      }
     msg << " ";
     }
   msg << ")";
@@ -4802,7 +4813,8 @@ bool cmMakefile::PolicyOptionalWarningEnabled(std::string const& var)
       return cmSystemTools::IsOn(val);
       }
     }
-  // Enable optional policy warnings with --debug-output or --trace.
+  // Enable optional policy warnings with --debug-output, --trace,
+  // or --trace-expand.
   cmake* cm = this->GetCMakeInstance();
   return cm->GetDebugOutput() || cm->GetTrace();
 }

Source/cmake.cxx

@@ -121,6 +121,7 @@ void cmWarnUnusedCliWarning(const std::string& variable,
 cmake::cmake()
 {
   this->Trace = false;
+  this->TraceExpand = false;
   this->WarnUninitialized = false;
   this->WarnUnused = false;
   this->WarnUnusedCli = true;
@@ -617,10 +618,17 @@ void cmake::SetArgs(const std::vector<std::string>& args,
       std::cout << "Running with debug output on.\n";
       this->SetDebugOutputOn(true);
       }
+    else if(arg.find("--trace-expand",0) == 0)
+      {
+      std::cout << "Running with expanded trace output on.\n";
+      this->SetTrace(true);
+      this->SetTraceExpand(true);
+      }
     else if(arg.find("--trace",0) == 0)
       {
       std::cout << "Running with trace output on.\n";
       this->SetTrace(true);
+      this->SetTraceExpand(false);
       }
     else if(arg.find("--warn-uninitialized",0) == 0)
       {

Source/cmake.h

@@ -270,6 +270,8 @@ class cmake
   // Do we want trace output during the cmake run.
   bool GetTrace() { return this->Trace;}
   void SetTrace(bool b) {  this->Trace = b;}
+  bool GetTraceExpand() { return this->TraceExpand;}
+  void SetTraceExpand(bool b) {  this->TraceExpand = b;}
   bool GetWarnUninitialized() { return this->WarnUninitialized;}
   void SetWarnUninitialized(bool b) {  this->WarnUninitialized = b;}
   bool GetWarnUnused() { return this->WarnUnused;}
@@ -378,6 +380,7 @@ private:
   WorkingMode CurrentWorkingMode;
   bool DebugOutput;
   bool Trace;
+  bool TraceExpand;
   bool WarnUninitialized;
   bool WarnUnused;
   bool WarnUnusedCli;

Source/cmakemain.cxx

@@ -83,6 +83,7 @@ static const char * cmDocumentationOptions[][2] =
    "useful on one try_compile at a time."},
   {"--debug-output", "Put cmake in a debug mode."},
   {"--trace", "Put cmake in trace mode."},
+  {"--trace-expand", "Put cmake in trace mode with variable expansion."},
   {"--warn-uninitialized", "Warn about uninitialized values."},
   {"--warn-unused-vars", "Warn about unused variables."},
   {"--no-warn-unused-cli", "Don't warn about command line options."},

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -140,6 +140,10 @@ set(RunCMake_TEST_OPTIONS --trace)
 run_cmake(trace)
 unset(RunCMake_TEST_OPTIONS)
 
+set(RunCMake_TEST_OPTIONS --trace-expand)
+run_cmake(trace-expand)
+unset(RunCMake_TEST_OPTIONS)
+
 set(RunCMake_TEST_OPTIONS --debug-trycompile)
 run_cmake(debug-trycompile)
 unset(RunCMake_TEST_OPTIONS)

Tests/RunCMake/CommandLine/trace-expand-stderr.txt

@@ -0,0 +1,2 @@
+^.*/Tests/RunCMake/CommandLine/CMakeLists.txt\(1\):  cmake_minimum_required\(VERSION 3.0 \)
+.*/Tests/RunCMake/CommandLine/CMakeLists.txt\(2\):  project\(trace-expand NONE \)