From 18473c9cdb258d0b7902528cff351c2faf33e90e Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sun, 29 Sep 2019 22:34:27 -0500
Subject: [PATCH] Fix code gen to respect declarator precedence (Closes gh-21)

---
 cgen/__init__.py  | 38 +++++++++++++++++++++++++++++++++++++-
 test/test_cgen.py | 20 +++++++++++++++++++-
 2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/cgen/__init__.py b/cgen/__init__.py
index 7d9a8b1..9d98e57 100644
--- a/cgen/__init__.py
+++ b/cgen/__init__.py
@@ -272,7 +272,7 @@ def get_decl_pair(self):
 class MaybeUnused(NestedDeclarator):
     def get_decl_pair(self):
         sub_tp, sub_decl = self.subdecl.get_decl_pair()
-        return sub_tp, ("%s __attribute__ ((unused))" % sub_decl)
+        return sub_tp, ("(%s __attribute__ ((unused)))" % sub_decl)
 
     mapper_method = "map_maybe_unused"
 
@@ -296,6 +296,16 @@ def __init__(self, subdecl):
 
     def get_decl_pair(self):
         sub_tp, sub_decl = self.subdecl.get_decl_pair()
+
+        if not isinstance(self.subdecl, (Pointer, POD, Value)):
+            # declarator might "change direction"
+            # (e.g. include an array declarator)
+            #
+            # Note that * binds less strongly than [], so these
+            # parentheses might not be necessary. Nonetheless,
+            # we insert them for clarity.
+            sub_decl = "(%s)" % sub_decl
+
         return sub_tp, ("*%s" % sub_decl)
 
     def struct_maker_code(self, data):
@@ -313,6 +323,16 @@ def alignment_requirement(self):
 class RestrictPointer(Pointer):
     def get_decl_pair(self):
         sub_tp, sub_decl = self.subdecl.get_decl_pair()
+
+        if not isinstance(self.subdecl, (Pointer, POD, Value)):
+            # declarator might "change direction"
+            # (e.g. include an array declarator)
+            #
+            # Note that * binds less strongly than [], so these
+            # parentheses might not be necessary. Nonetheless,
+            # we insert them for clarity.
+            sub_decl = "(%s)" % sub_decl
+
         return sub_tp, ("*__restrict__ %s" % sub_decl)
 
     mapper_method = "map_restrict_pointer"
@@ -321,6 +341,16 @@ def get_decl_pair(self):
 class Reference(Pointer):
     def get_decl_pair(self):
         sub_tp, sub_decl = self.subdecl.get_decl_pair()
+
+        if not isinstance(self.subdecl, (Pointer, POD, Value)):
+            # declarator might "change direction"
+            # (e.g. include an array declarator)
+            #
+            # Note that * binds less strongly than [], so these
+            # parentheses might not be necessary. Nonetheless,
+            # we insert them for clarity.
+            sub_decl = "(%s)" % sub_decl
+
         return sub_tp, ("&%s" % sub_decl)
 
     mapper_method = "map_reference"
@@ -337,6 +367,12 @@ def get_decl_pair(self):
             count_str = ""
         else:
             count_str = str(self.count)
+
+        if not isinstance(self.subdecl, (POD, Value, ArrayOf)):
+            # declarator might "change direction"
+            # (e.g. include a pointer declarator)
+            sub_decl = "(%s)" % sub_decl
+
         return sub_tp, ("%s[%s]" % (sub_decl, count_str))
 
     def struct_maker_code(self, name):
diff --git a/test/test_cgen.py b/test/test_cgen.py
index b1de365..cbb3d9f 100644
--- a/test/test_cgen.py
+++ b/test/test_cgen.py
@@ -1,7 +1,9 @@
+import sys
+
 from cgen import (
         POD, Struct, FunctionBody, FunctionDeclaration,
         For, If, Assign, Value, Block, ArrayOf, Comment,
-        Template)
+        Template, Pointer)
 import numpy as np
 
 
@@ -46,3 +48,19 @@ def test_cgen():
     print(s)
     print(f_body)
     print(t_decl)
+
+
+def test_ptr_to_array():
+    t1 = Pointer(ArrayOf(Pointer(POD(np.float32, "xxx")), 2))
+    assert str(t1) == "float *((*xxx)[2]);"
+
+    t2 = Pointer(Pointer(ArrayOf(POD(np.float32, "yyy"), 2)))
+    assert str(t2) == "float **(yyy[2]);"
+
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1:
+        exec(sys.argv[1])
+    else:
+        from pytest import main
+        main([__file__])