Semantic patch for palloc_array and palloc_object

Macros were added to the palloc API in commit 2016055 to improve
type-safety, but very few instances were replaced. This adds a cocci script to
do that replacement. The semantic patch deliberately do not replace instances
where the type of the variable and the type used in the macro does not match.

Author: mkindahl

cocci/palloc_array.cocci

@@ -0,0 +1,157 @@
+// Since PG16 there are array versions of common palloc operations, so
+// we can use those instead.
+//
+// We ignore cases where we have a anonymous struct and also when the
+// type of the variable being assigned to is different from the
+// inferred type.
+//
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual report
+virtual context
+
+// These rules (soN) are needed to rewrite types of the form
+// sizeof(T[C]) to C * sizeof(T) since Cocci cannot (currently) handle
+// it.
+@initialize:python@
+@@
+import re
+
+CRE = re.compile(r'(.*)\s+\[\s+(\d+)\s+\]$')
+
+def is_array_type(s):
+    mre = CRE.match(s)
+    return (mre is not None)
+
+@so1 depends on patch@
+type T : script:python() {  is_array_type(T) };
+@@
+palloc(sizeof(T))
+
+@script:python so2 depends on patch@
+T << so1.T;
+T2;
+E;
+@@
+mre = CRE.match(T)
+coccinelle.T2 = cocci.make_type(mre.group(1))
+coccinelle.E = cocci.make_expr(mre.group(2))
+
+@depends on patch@
+type so1.T;
+type so2.T2;
+expression so2.E;
+@@
+- palloc(sizeof(T))
++ palloc(E * sizeof(T2))
+
+@r1 depends on report || context@
+type T !~ "^struct {";
+expression E;
+position p;
+idexpression T *I;
+identifier alloc = {palloc0, palloc};
+@@
+* I = alloc@p(E * sizeof(T))
+
+@script:python depends on report@
+p << r1.p;
+alloc << r1.alloc;
+@@
+coccilib.report.print_report(p[0], f"this {alloc} can be replaced with {alloc}_array")
+
+@depends on patch@
+type T !~ "^struct {";
+expression E;
+T *P;
+idexpression T* I;
+constant C;
+identifier alloc = {palloc0, palloc};
+fresh identifier alloc_array = alloc ## "_array";
+@@
+(
+- I = (T*) alloc(E * sizeof( \( *P \| P[C] \) ))
++ I = alloc_array(T, E)
+|
+- I = (T*) alloc(E * sizeof(T))
++ I = alloc_array(T, E)
+|
+- I = alloc(E * sizeof( \( *P \| P[C] \) ))
++ I = alloc_array(T, E)
+|
+- I = alloc(E * sizeof(T))
++ I = alloc_array(T, E)
+)
+
+@r3 depends on report || context@
+type T !~ "^struct {";
+expression E;
+idexpression T *P;
+idexpression T *I;
+position p;
+@@
+* I = repalloc@p(P, E * sizeof(T))
+
+@script:python depends on report@
+p << r3.p;
+@@
+coccilib.report.print_report(p[0], "this repalloc can be replaced with repalloc_array")
+
+@depends on patch@
+type T !~ "^struct {";
+expression E;
+idexpression T *P1;
+idexpression T *P2;
+idexpression T *I;
+constant C;
+@@
+(
+- I = (T*) repalloc(P1, E * sizeof( \( *P2 \| P2[C] \) ))
++ I = repalloc_array(P1, T, E)
+|
+- I = (T*) repalloc(P1, E * sizeof(T))
++ I = repalloc_array(P1, T, E)
+|
+- I = repalloc(P1, E * sizeof( \( *P2 \| P2[C] \) ))
++ I = repalloc_array(P1, T, E)
+|
+- I = repalloc(P1, E * sizeof(T))
++ I = repalloc_array(P1, T, E)
+)
+
+@r4 depends on report || context@
+type T !~ "^struct {";
+position p;
+idexpression T* I;
+identifier alloc = {palloc, palloc0};
+@@
+* I = alloc@p(sizeof(T))
+
+@script:python depends on report@
+p << r4.p;
+alloc << r4.alloc;
+@@
+coccilib.report.print_report(p[0], f"this {alloc} can be replaced with {alloc}_object")
+
+@depends on patch@
+type T !~ "^struct {";
+T* P;
+idexpression T *I;
+constant C;
+identifier alloc = {palloc, palloc0};
+fresh identifier alloc_object = alloc ## "_object";
+@@
+(
+- I = (T*) alloc(sizeof( \( *P \| P[C] \) ))
++ I = alloc_object(T)
+|
+- I = (T*) alloc(sizeof(T))
++ I = alloc_object(T)
+|
+- I = alloc(sizeof( \( *P \| P[C] \) ))
++ I = alloc_object(T)
+|
+- I = alloc(sizeof(T))
++ I = alloc_object(T)
+)