Add Coccinelle lint checks for non-_RO accessors used with pointers to const (#7622)

* Use _RO accessors for const targets

* use read-only accessors when appropriate (#7615)

* one more _RO

Co-authored-by: Benjamin Schwendinger <52290390+ben-schwen@users.noreply.github.com>

* review suggestions

Co-authored-by: Benjamin Schwendinger <52290390+ben-schwen@users.noreply.github.com>

* botched suggested change

* Use more read-only accessors

* gfirstlast: use _RO accessors

Keep the casts because they are currently necessary for the integer64 case.

* add coccinelle rules to use read only accessors

* CI should also run when cocci files are touched

* cocci_linter.R: fix zero-length error reports

* use_ro_accessors.cocci: expand linter rules

* Apply suggestions from code review

Co-authored-by: Michael Chirico <chiricom@google.com>

* Revert "cocci_linter.R: fix zero-length error reports"

This reverts commit 70d37da.

* Fix the file path list element

Setting $c_obj instead of $path caused the error messages to be
zero-length due to the latter being returned as NULL.

Co-Authored-By: Michael Chirico <chiricom@google.com>
Co-Authored-By: Benjamin Schwendinger <52290390+ben-schwen@users.noreply.github.com>

* Reorder checks according to SEXPTYPE order

---------

Co-authored-by: Michael Chirico <chiricom@google.com>
Co-authored-by: Benjamin Schwendinger <52290390+ben-schwen@users.noreply.github.com>
Co-authored-by: Benjamin Schwendinger <benjaminschwe@gmail.com>

Author: 3 people

.ci/linters/c/00preprocess.R

@@ -1,5 +1,5 @@
 .preprocess = function (f) list(
-  c_obj = f, lines = readLines(f),
+  path = f, lines = readLines(f),
   preprocessed = system2(
     "gcc", shQuote(c("-fpreprocessed", "-E", f)),
     stdout = TRUE, stderr = FALSE

.ci/linters/cocci/use_ro_accessors.cocci

@@ -0,0 +1,79 @@
+/* Ensure _RO accessors are used for assignment to 'const' variables */
+@@
+type T;
+const T *variable;
+expression E;
+@@
+- variable = RAW(E)
++ variable = RAW_RO(E)
+
+@@
+type T;
+const T *variable;
+expression E;
+@@
+- variable = LOGICAL(E)
++ variable = LOGICAL_RO(E)
+
+@@
+type T;
+const T *variable;
+expression E;
+@@
+- variable = INTEGER(E)
++ variable = INTEGER_RO(E)
+
+@@
+type T;
+const T *variable;
+expression E;
+@@
+- variable = REAL(E)
++ variable = REAL_RO(E)
+
+@@
+type T;
+const T *variable;
+expression E;
+@@
+- variable = COMPLEX(E)
++ variable = COMPLEX_RO(E)
+
+/* Just use _RO accessors directly instead of 'const' casting the writeable one */
+@@
+expression E;
+type T;
+@@
+-(const T*) RAW(E)
++RAW_RO(E)
+
+@@
+expression E;
+@@
+-(const int*) LOGICAL(E)
++LOGICAL_RO(E)
+
+@@
+expression E;
+@@
+-(const int*) INTEGER(E)
++INTEGER_RO(E)
+
+@@
+expression E;
+@@
+-(const double*) REAL(E)
++REAL_RO(E)
+@@
+expression E;
+type T;
+@@
+-(const T*) COMPLEX(E)
++COMPLEX_RO(E)
+
+@@
+expression E;
+type T;
+@@
+-(const T*) STRING_PTR(E)
++STRING_PTR_RO(E)

.github/workflows/code-quality.yaml

@@ -29,6 +29,7 @@ jobs:
             c:
               - '**/*.c'
               - '**/*.h'
+              - '.ci/linters/cocci/**/*.cocci'
             po:
               - 'po/**/*.po'
             md: