shadowing in the QL language specification

Author: ginsbach

docs/codeql/ql-language-reference/ql-language-specification.rst

@@ -133,17 +133,32 @@ The program is invalid if any of these environments is not definite.
 Module environments
 ~~~~~~~~~~~~~~~~~~~
 
-For each of modules, types, and predicates, a module *imports*, *declares*, and *exports* an environment. These are defined as follows (with X denoting the type of entity we are currently considering):
+For each of modules, types, predicates, module signatures, type signatures, and predicates signatures, we distinguish five environments: *publically declared*, *privately declared*, *exported*, and *visible*.
+These are defined as follows (with X denoting the type of entity we are currently considering):
 
--  The *imported X environment* of a module is defined to be the union of the exported X environments of all the modules which the current module directly imports (see "`Import directives <#import-directives>`__").
+-  The *privately declared X environment* of a module is the multimap of X declarations and aliases in the module itself that are annotated as ``private``.
 
--  The *declared X environment* of a module is the multimap of X declarations in the module itself.
+-  The *publically declared X environment* of a module is the multimap of X declarations and aliases in the module itself that are not annotated as ``private``.
 
--  The *exported X environment* of a module is the union of the exported X environments of the modules which the current module directly imports (excluding ``private`` imports), and the declared X environment of the current module (excluding ``private`` declarations).
+-  The *exported X environment* of a module is the union of
 
--  The *external X environment* of a module is the visible X environment of the enclosing module, if there is one, and otherwise the global X environment.
+    1.  its *publically declared X environment*, and
 
--  The *visible X environment* is the union of the imported X environment, the declared X environment, and the external X environment.
+    2.  for each module which the current module directly imports (excluding ``private`` imports - see "`Import directives <#import-directives>`__"): all entries from the *exported X environment* that have a key not present in the *publically declared X environment* of the current module.
+
+-  The *visible X environment* of a module is the union of
+
+    1. its *exported X environment*, and
+
+    2. its *privately declared X environment*, and
+
+    3. the *global X environment*, and
+
+    4. for each module which the current module privately imports: all entries from the *exported X environment* that have a key not present in the *publically declared X environment* of the current module, and
+
+    5. if there is an enclosing module: all entries from the *visible X environment* of the enclosing module that have a key not present in the *publically declared X environment* of the current module, and
+
+    6. all parameters of the current module that are of type X.
 
 The program is invalid if any of these environments is not definite.