Fix Coccinelle allocation cast linter (#7039)

* Fix malloc/calloc/realloc cast linter

Tested by manually calling spatch on an older version of data.table

* Coccinelle linter: look at preprocessed source

Otherwise major sources of potential problems fail to parse altogether
and get skipped. Make sure to report non-zero exit codes in addition to
non-empty diffs. Don't suggest applying the diffs; that won't work on
preprocessed source.

Author: aitap

.ci/linters/c/cocci_linter.R

@@ -1,20 +1,23 @@
 cocci_linter = if (!nzchar(Sys.which("spatch"))) function(...) {} else function(c_obj) {
-  bad <- FALSE
+  bad = FALSE
+  tmp = tempfile(fileext = '.c')
+  on.exit(unlink(tmp))
+  writeLines(c_obj$preprocessed, tmp)
   for (spfile in list.files(".ci/linters/cocci", full.names = TRUE)) {
-    # Coccinelle parser gets confused sometimes, so ignore stderr and the exit code
-    out = suppressWarnings(system2(
+    out = system2(
       "spatch",
-      shQuote(c(
-        "--sp-file", spfile, c_obj$path, "--recursive-includes",
-        "-I", R.home("include"), "-I", "src"
-      )),
+      shQuote(c("--sp-file", spfile, tmp)),
       stdout = TRUE, stderr = FALSE
-    ))
+    )
     if (length(out) > 0) {
-      cat(sprintf("In file '%s', Coccinelle patch '%s' recommends the following changes:\n", c_obj$path, spfile))
+      cat(sprintf("In file '%s', Coccinelle linter '%s' located the following problems:\n", c_obj$path, spfile))
       writeLines(out)
-      bad <- TRUE
+      bad = TRUE
+    }
+    if (!is.null(status <- attr(out, 'status'))) {
+      cat(sprintf("While working on file '%s', Coccinelle linter '%s' failed with exit code %d:\n", c_obj$path, spfile, status))
+      bad = TRUE
     }
   }
-  if (bad) stop("Please apply the changes above or fix the linter")
+  if (bad) stop("Please investigate the problems above.")
 }

.ci/linters/cocci/malloc_return_value_cast.cocci

@@ -5,8 +5,10 @@ expression E;
 - (T)
   malloc(E)
 
+@calloc_realloc_return_value_cast expression@
+type T;
+expression E1, E2;
+identifier alloc =~ "^(c|re)alloc$";
+@@
 - (T)
-  calloc(_, E)
-
-- (T)
-  realloc(_, E)
+  alloc(E1, E2)