file(GENERATE): Add policy CMP0070 to define relative path behavior

Previously `file(GENERATE)` did not define any behavior for relative
paths given to the `OUTPUT` or `INPUT` arguments.  Define behavior
consistent with CMake conventions and add a policy to provide
compatibility for projects that relied on the old accidental behavior.

Fixes: #16786

1 files changed, 12 insertions, 1 deletions

diff --git a/Source/cmGeneratorExpressionEvaluationFile.h b/Source/cmGeneratorExpressionEvaluationFile.h
index 9872746..ecf919d 100644
--- a/Source/cmGeneratorExpressionEvaluationFile.h
+++ b/Source/cmGeneratorExpressionEvaluationFile.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "cmGeneratorExpression.h"
+#include "cmPolicies.h"
 #include "cm_auto_ptr.hxx"
 #include "cm_sys_stat.h"
 
@@ -21,7 +22,8 @@ public:
   cmGeneratorExpressionEvaluationFile(
     const std::string& input,
     CM_AUTO_PTR<cmCompiledGeneratorExpression> outputFileExpr,
-    CM_AUTO_PTR<cmCompiledGeneratorExpression> condition, bool inputIsContent);
+    CM_AUTO_PTR<cmCompiledGeneratorExpression> condition, bool inputIsContent,
+    cmPolicies::PolicyStatus policyStatusCMP0070);
 
   void Generate(cmLocalGenerator* lg);
 
@@ -35,12 +37,21 @@ private:
                 cmCompiledGeneratorExpression* inputExpression,
                 std::map<std::string, std::string>& outputFiles, mode_t perm);
 
+  enum PathRole
+  {
+    PathForInput,
+    PathForOutput
+  };
+  std::string FixRelativePath(std::string const& filePath, PathRole role,
+                              cmLocalGenerator* lg);
+
 private:
   const std::string Input;
   const CM_AUTO_PTR<cmCompiledGeneratorExpression> OutputFileExpr;
   const CM_AUTO_PTR<cmCompiledGeneratorExpression> Condition;
   std::vector<std::string> Files;
   const bool InputIsContent;
+  cmPolicies::PolicyStatus PolicyStatusCMP0070;
 };
 
 #endif