fixes #24008; triggers a recompilation on output executables changes when switching release/debug modes (#24193)

fixes #24008

The old logic didn't check the contents of the output executables, when
it switched release->debug->release, it picked up the Json files used in
the first release building, the content of which didn't change. So it
mistook the executables which are built by the second debug building as
the functioning one.

`changeDetectedViaJsonBuildInstructions` needs a way to distinguish the
executables generated by different buildings.

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/extccomp.nim b/compiler/extccomp.nim
index a8b6489b8..e66746fbb 100644
--- a/compiler/extccomp.nim
+++ b/compiler/extccomp.nim
@@ -1000,10 +1000,11 @@ proc jsonBuildInstructionsFile*(conf: ConfigRef): AbsoluteFile =
   # works out of the box with `hashMainCompilationParams`.
   result = getNimcacheDir(conf) / conf.outFile.changeFileExt("json")
 
-const cacheVersion = "D20210525T193831" # update when `BuildCache` spec changes
+const cacheVersion = "D20240927T193831" # update when `BuildCache` spec changes
 type BuildCache = object
   cacheVersion: string
   outputFile: string
+  outputLastModificationTime: string
   compile: seq[(string, string)]
   link: seq[string]
   linkcmd: string
@@ -1047,6 +1048,7 @@ proc writeJsonBuildInstructions*(conf: ConfigRef; deps: StringTableRef) =
           bcache.depfiles.add (path, $secureHashFile(path))
 
     bcache.nimexe = hashNimExe()
+    bcache.outputLastModificationTime = $getLastModificationTime(bcache.outputFile)
   conf.jsonBuildFile = conf.jsonBuildInstructionsFile
   conf.jsonBuildFile.string.writeFile(bcache.toJson.pretty)
 
@@ -1067,6 +1069,8 @@ proc changeDetectedViaJsonBuildInstructions*(conf: ConfigRef; jsonFile: Absolute
     # xxx optimize by returning false if stdin input was the same
   for (file, hash) in bcache.depfiles:
     if $secureHashFile(file) != hash: return true
+  if bcache.outputLastModificationTime != $getLastModificationTime(bcache.outputFile):
+    return true
 
 proc runJsonBuildInstructions*(conf: ConfigRef; jsonFile: AbsoluteFile) =
   var bcache: BuildCache = default(BuildCache)
@@ -1083,7 +1087,7 @@ proc runJsonBuildInstructions*(conf: ConfigRef; jsonFile: AbsoluteFile) =
       "jsonscript command outputFile '$1' must match '$2' which was specified during --compileOnly, see \"outputFile\" entry in '$3' " %
       [outputCurrent, output, jsonFile.string])
   var cmds: TStringSeq = default(TStringSeq)
-  var prettyCmds: TStringSeq= default(TStringSeq)
+  var prettyCmds: TStringSeq = default(TStringSeq)
   let prettyCb = proc (idx: int) = writePrettyCmdsStderr(prettyCmds[idx])
   for (name, cmd) in bcache.compile:
     cmds.add cmd