fixes #22101; std/pegs with nim cpp --mm:orc --exceptions:goto create…

…s invalid C++ (#24531)

fixes #22101

The old implementation generates

`auto T = value;` for the cpp backend which causes problems for goto
exceptions. This PR puts the declaration of `T` to the cpsLocals parts
and makes it compatible with goto exceptions.

compiler/ccgcalls.nim

@@ -141,7 +141,7 @@ proc fixupCall(p: BProc, le, ri: PNode, d: var TLoc,
           d.snippet = extract(result)
           excl d.flags, lfSingleUse
         else:
-          if d.k == locNone and p.splitDecls == 0:
+          if d.k == locNone and p.splitDecls == 0 and p.config.exc != excGoto:
             d = getTempCpp(p, typ.returnType, extract(result))
           else:
             if d.k == locNone: d = getTemp(p, typ.returnType)

tests/stdlib/tpegs.nim

@@ -1,5 +1,5 @@
 discard """
-  matrix: "--mm:refc; --mm:orc"
+  matrix: "--mm:refc; --mm:orc; --exceptions:goto"
   targets: "c cpp js"
   output: '''
 PEG AST traversal output