string(TIMESTAMP): add %f specifier for microseconds

The %f specified extends the string(TIMESTAMP) and file(TIMESTAMP)
commands to output the timestamp with a microsecond resolution.
This convention is offered by python's datetime module.
Before, the precision was limited to seconds.

The implementation is done by extending existing cmTimestamp methods
with a `microseconds` parameter. This parameter is optional in order to
be backwards compatible. The timestamps are now received in a
cross-platform manner using libuv, since the standard C functions like
time() don't allow for sub-second precision.

This requires libuv 1.28 or higher.  We already require higher than
that on Windows, so update the required version for other platforms.

Implements: #19335

1 files changed, 7 insertions, 1 deletions

diff --git a/Source/cmTimestamp.h b/Source/cmTimestamp.h
index 0e2c200..ada5006 100644
--- a/Source/cmTimestamp.h
+++ b/Source/cmTimestamp.h
@@ -4,6 +4,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cstdint>
 #include <ctime>
 #include <string>
 
@@ -23,9 +24,14 @@ public:
   std::string CreateTimestampFromTimeT(time_t timeT, std::string formatString,
                                        bool utcFlag) const;
 
+  std::string CreateTimestampFromTimeT(time_t timeT, uint32_t microseconds,
+                                       std::string formatString,
+                                       bool utcFlag) const;
+
 private:
   time_t CreateUtcTimeTFromTm(struct tm& timeStruct) const;
 
   std::string AddTimestampComponent(char flag, struct tm& timeStruct,
-                                    time_t timeT) const;
+                                    time_t timeT,
+                                    uint32_t microseconds = 0) const;
 };