handle exceptions in `generate_makefile` tool (#5985)

Update `generate_makefile` to produce sensible error message in all
exceptional situations, instead of just some of them. These may surface
as one of the first things to someone getting started with the repo.

tools/generate_makefile.nim

@@ -1,9 +1,12 @@
+# beacon_chain
 # Copyright (c) 2020-2024 Status Research & Development GmbH
 # Licensed and distributed under either of
 #   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
 #   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
+{.push raises: [].}
+
 # Generate a Makefile from the JSON file produce by the Nim compiler with
 # "--compileOnly". Suitable for Make-controlled parallelisation, down to the GCC
 # LTO level.
@@ -12,7 +15,7 @@ import std/[json, os, strutils]
 
 # Ripped off from Nim's `linkViaResponseFile()` in "compiler/extccomp.nim".
 # It lets us get around a command line length limit on Windows.
-proc processLinkCmd(cmd, linkerArgs: string): string =
+proc processLinkCmd(cmd, linkerArgs: string): string {.raises: [IOError].} =
   # Extracting the linker.exe here is a bit hacky but the best solution
   # given ``buildLib``'s design.
   var
@@ -51,8 +54,21 @@ proc main() =
     quit(QuitFailure)
 
   let
-    data = json.parseFile(jsonPath)
-    makefile = open(makefilePath, fmWrite)
+    data =
+      try:
+        json.parseFile(jsonPath)
+      except IOError as exc:
+        echo "Failed to parse file: ", jsonPath, " - [IOError]: ", exc.msg
+        quit(QuitFailure)
+      except Exception as exc:
+        echo "Failed to parse file: ", jsonPath, " - [Exception]: ", exc.msg
+        quit(QuitFailure)
+    makefile =
+      try:
+        open(makefilePath, fmWrite)
+      except IOError as exc:
+        echo "Failed to open file: ", makefilePath, " - [IOError]: ", exc.msg
+        quit(QuitFailure)
 
   defer:
     makefile.close()
@@ -62,6 +78,8 @@ proc main() =
     found: bool
     cmd: string
 
+  try:
+    try:
       for compile in data["compile"]:
         cmd = compile[1].getStr().replace('\\', '/')
         objectPath = ""
@@ -75,19 +93,55 @@ proc main() =
         if found == false or objectPath == "":
           echo "Could not find the object file in this command: ", cmd
           quit(QuitFailure)
-    makefile.writeLine("$#: $#" % [objectPath.replace('\\', '/'), compile[0].getStr().replace('\\', '/')])
+        try:
+          makefile.writeLine("$#: $#" % [
+            objectPath.replace('\\', '/'),
+            compile[0].getStr().replace('\\', '/')])
           makefile.writeLine("\t+ $#\n" % cmd)
+        except ValueError:
+          # https://github.com/nim-lang/Nim/pull/23356
+          raiseAssert "Arguments match the format string"
+    except KeyError:
+      echo "File lacks `compile` key: ", jsonPath
+      quit(QuitFailure)
 
     var objects: seq[string]
+    try:
       for obj in data["link"]:
         objects.add(obj.getStr().replace('\\', '/'))
+    except KeyError:
+      echo "File lacks `link` key: ", jsonPath
+      quit(QuitFailure)
+    try:
       makefile.writeLine("OBJECTS := $#\n" % objects.join(" \\\n"))
+    except ValueError:
+      # https://github.com/nim-lang/Nim/pull/23356
+      raiseAssert "Arguments match the format string"
 
     makefile.writeLine(".PHONY: build")
     makefile.writeLine("build: $(OBJECTS)")
-  makefile.writeLine("\t+ $#" % processLinkCmd(data["linkcmd"].getStr().replace('\\', '/'), makefilePath & ".linkerArgs"))
+    let linkerArgs = makefilePath & ".linkerArgs"
+    try:
+      makefile.writeLine("\t+ $#" % processLinkCmd(
+        data["linkcmd"].getStr().replace('\\', '/'), linkerArgs))
+    except IOError as exc:
+      echo "Failed to write file: ", linkerArgs, " - [IOError]: ", exc.msg
+      quit(QuitFailure)
+    except ValueError:
+      # https://github.com/nim-lang/Nim/pull/23356
+      raiseAssert "Arguments match the format string"
     if data.hasKey("extraCmds"):
+      try:
         for cmd in data["extraCmds"]:
+          try:
             makefile.writeLine("\t+ $#" % cmd.getStr().replace('\\', '/'))
+          except ValueError:
+            # https://github.com/nim-lang/Nim/pull/23356
+            raiseAssert "Arguments match the format string"
+      except KeyError:
+        raiseAssert "just checked"
+  except IOError as exc:
+    echo "Failed to write file: ", makefilePath, " - [IOError]: ", exc.msg
+    quit(QuitFailure)
 
 main()