viml/reltime(): allow negative result #10453

- define proftime_T as signed integer
- profile_sub(): allow negative result

closes #10452

4 files changed, 16 insertions, 6 deletions

diff --git a/src/nvim/os/time.c b/src/nvim/os/time.c
index 18239c5566..1094fbc946 100644
--- a/src/nvim/os/time.c
+++ b/src/nvim/os/time.c
@@ -39,7 +39,7 @@ void time_init(void)
 /// @see gettimeofday(2)
 ///
 /// @return Current time in microseconds.
-uint64_t os_utime(void)
+int64_t os_utime(void)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   uv_timeval64_t tm;
@@ -47,8 +47,8 @@ uint64_t os_utime(void)
   if (e != 0 || tm.tv_sec < 0 || tm.tv_usec < 0) {
     return 0;
   }
-  uint64_t rv = (uint64_t)tm.tv_sec * 1000 * 1000;  // s => μs
-  STRICT_ADD(rv, tm.tv_usec, &rv, uint64_t);
+  int64_t rv = tm.tv_sec * 1000 * 1000;  // s => μs
+  STRICT_ADD(rv, tm.tv_usec, &rv, int64_t);
   return rv;
 }
 
diff --git a/src/nvim/profile.c b/src/nvim/profile.c
index cc12e00396..ae3f1d9b5e 100644
--- a/src/nvim/profile.c
+++ b/src/nvim/profile.c
@@ -61,7 +61,7 @@ proftime_T profile_setlimit(int64_t msec) FUNC_ATTR_WARN_UNUSED_RESULT
   }
   assert(msec <= (INT64_MAX / 1000LL) - 1);
 
-  proftime_T usec = (proftime_T)msec * 1000ULL;
+  proftime_T usec = msec * 1000;
   return os_utime() + usec;
 }
 
@@ -111,7 +111,7 @@ proftime_T profile_add(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
 /// @return `tm1` - `tm2`
 proftime_T profile_sub(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
 {
-  return tm1 > tm2 ? tm1 - tm2 : 0;  // os_utime() may go backwards.
+  return tm1 - tm2;
 }
 
 /// Adds the `self` time from the total time and the `children` time.
diff --git a/src/nvim/profile.h b/src/nvim/profile.h
index 7b378577ce..2608514313 100644
--- a/src/nvim/profile.h
+++ b/src/nvim/profile.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 #include <time.h>
 
-typedef uint64_t proftime_T;
+typedef int64_t proftime_T;
 
 #define TIME_MSG(s) do { \
     if (time_fd != NULL) time_msg(s, NULL); \
diff --git a/test/functional/eval/reltime_spec.lua b/test/functional/eval/reltime_spec.lua
index 0181f09024..ef7a3a148f 100644
--- a/test/functional/eval/reltime_spec.lua
+++ b/test/functional/eval/reltime_spec.lua
@@ -33,4 +33,14 @@ describe('reltimestr(), reltimefloat()', function()
     ok(reltimefloat(differs) < 1.0)
 
   end)
+
+  it('reltime() allows negative result #10452', function()
+    local older_time = reltime()
+    command('sleep 1m')
+    local newer_time = reltime()
+    -- Should be something like -0.002123.
+    local rv = tonumber(reltimestr(reltime(newer_time, older_time)))
+    ok(rv < 0)
+    ok(rv > -10)
+  end)
 end)