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Merged
jnthntatum merged 4 commits into from
Jan 12, 2026
Merged

Add clarification on scoping rules. #506

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15c999a
Add clarification on scoping rules.
jnthntatum Jan 6, 2026
d65edd6
Rephrase
jnthntatum Jan 7, 2026
b8b1290
Rephrase 2
jnthntatum Jan 7, 2026
6bb648c
Respond to feedback.
jnthntatum Jan 7, 2026
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15 changes: 15 additions & 0 deletions doc/langdef.md
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,21 @@ name which resolves in the current lexical scope is used. For example, if
possible field selection, then `a.b.c` takes priority over the interpretation
`(a.b).c`.

Note: Comprehensions (.exists, .all, etc) introduce new scopes that add
variables as simple identifiers. When resolving a name within a comprehension
body, the name is first compared against the variables declared by the
comprehension. If there is a match, the name resolves to that variable, taking
precedence over the package-based resolution rules above. If not,
resolution proceeds checking for variable matches in parent
comprehension scopes recursively. Finally the name follows the package
resolution rules above against declarations in the environment. A name with a
leading '.' always resolves in the root scope, bypassing local scopes from
comprehensions.

For example, in `[1].exists(x, x == 1)`, `x` is a local variable which shadows
any identifier named 'x' in ancestor scopes or the package namespace. In
`[1].exists(x, .x == 1)`, x is the global variable `x`.

## Values

Values in CEL represent any of the following:
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59 changes: 59 additions & 0 deletions tests/simple/testdata/bindings_ext.textproto
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Expand Up @@ -40,4 +40,63 @@ section: {
bool_value: true
}
}
test: {
name: "shadowing"
expr: "cel.bind(x, 0, x == 0)"
type_env: {
name: "x"
ident: {
type: { primitive: INT64 }
}
}
bindings: {
key: "x"
value: {
value: { int64_value: 1 }
}
}
value: {
bool_value: true
}
}
test: {
name: "shadowing_namespace_resolution"
expr: "cel.bind(x, 0, x == 0)"
container: "com.example"
type_env: {
name: "com.example.x"
ident: {
type: { primitive: INT64 }
}
}
bindings: {
key: "com.example.x"
value: {
value: { int64_value: 1 }
}
}
value: {
bool_value: true
}
}
test: {
name: "shadowing_namespace_resolution_selector"
expr: "cel.bind(x, {'y': 0}, x.y == 0)"
container: "com.example"
type_env: {
name: "com.example.x.y"
ident: {
type: { primitive: INT64 }
}
}
bindings: {
key: "com.example.x.y"
value: {
value: { int64_value: 1 }
}
}
value: {
bool_value: true
}
}
}
203 changes: 197 additions & 6 deletions tests/simple/testdata/namespace.textproto
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Expand Up @@ -11,7 +11,7 @@ section {
expr: "x.y"
value: { bool_value: true }
type_env: {
name: "x.y",
name: "x.y"
ident: { type: { primitive: BOOL } }
}
bindings: {
Expand All @@ -28,11 +28,11 @@ section {
expr: "y"
container: "x"
type_env: {
name: "x.y",
name: "x.y"
ident: { type: { primitive: BOOL } }
}
type_env: {
name: "y",
name: "y"
ident: { type: { primitive: STRING } }
}
bindings: {
Expand All @@ -50,11 +50,11 @@ section {
expr: "y"
container: "x"
type_env: {
name: "x.y",
name: "x.y"
ident: { type: { primitive: BOOL } }
}
type_env: {
name: "y",
name: "y"
ident: { type: { primitive: BOOL } }
}
bindings: {
Expand All @@ -65,7 +65,198 @@ section {
key: "y"
value: { value: { bool_value: false } }
}
disable_check: true ## ensure unchecked ASTs resolve the same as checked ASTs
disable_check: true ## ensure unchecked ASTs resolve the same as checked ASTs
value: { bool_value: true }
}
}
section {
name: "namespace_shadowing"
description: "Variable shadowing in comprehensions"
test {
name: "basic"
expr: "y"
container: "com.example"
type_env: {
name: "com.example.y"
ident: { type: { primitive: BOOL } }
}
type_env: {
name: "y"
ident: { type: { primitive: STRING } }
}
bindings: {
key: "com.example.y"
value: { value: { bool_value: true } }
}
bindings: {
key: "y"
value: { value: { string_value: "string" } }
}
value: { bool_value: true }
}
test {
name: "disambiguation"
expr: ".y"
container: "com.example"
type_env: {
name: "com.example.y"
ident: { type: { primitive: STRING } }
}
type_env: {
name: "y"
ident: { type: { primitive: STRING } }
}
bindings: {
key: "com.example.y"
value: { value: { string_value: "com.example.y" } }
}
bindings: {
key: "y"
value: { value: { string_value: "y" } }
}
value: { string_value: "y" }
}
test {
name: "comprehension_shadowing"
expr: "[0].exists(y, y == 0)"
container: "com.example"
type_env: {
name: "com.example.y"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "com.example.y"
value: { value: { int64_value: 42 } }
}
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_disambiguation"
expr: "['compre'].exists(y, .y == 'y')"
container: "com.example"
type_env: {
name: "y"
ident: { type: { primitive: STRING } }
}
bindings: {
key: "y"
value: { value: { string_value: "y" } }
}
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_parse_only"
expr: "[0].exists(y, y == 0)"
container: "com.example"
type_env: {
name: "com.example.y"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "com.example.y"
value: { value: { int64_value: 42 } }
}
disable_check: true
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_selector"
expr: "[{'z': 0}].exists(y, y.z == 0)"
type_env: {
name: "y.z"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "y.z"
value: { value: { int64_value: 42 } }
}
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_selector_parse_only"
expr: "[{'z': 0}].exists(y, y.z == 0)"
type_env: {
name: "y.z"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "y.z"
value: { value: { int64_value: 42 } }
}
disable_check: true
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_namespaced_selector"
expr: "[{'z': 0}].exists(y, y.z == 0)"
container: "com.example"
type_env: {
name: "com.example.y.z"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "com.example.y.z"
value: { value: { int64_value: 42 } }
}
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_namespaced_selector_parse_only"
expr: "[{'z': 0}].exists(y, y.z == 0)"
container: "com.example"
type_env: {
name: "com.example.y.z"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "com.example.y.z"
value: { value: { int64_value: 42 } }
}
disable_check: true
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_namespaced_selector_disambiguation"
expr: "[{'z': 'compre'}].exists(y, .y.z == 'y.z')"
container: "com.example"
type_env: {
name: "com.example.y.z"
ident: { type: { primitive: STRING } }
}
type_env: {
name: "y.z"
ident: { type: { primitive: STRING } }
}
bindings: {
key: "com.example.y.z"
value: { value: { string_value: "com.example.y.z" } }
}
bindings: {
key: "y.z"
value: { value: { string_value: "y.z" } }
}
value: { bool_value: true }
}
test {
name: "comprehension_shadowing_nesting"
expr: "[1].exists(y, [0].exists(y, y == 0))"
container: "com.example"
type_env: {
name: "com.example.y"
ident: { type: { primitive: INT64 } }
}
type_env: {
name: "y"
ident: { type: { primitive: INT64 } }
}
bindings: {
key: "com.example.y"
value: { value: { int64_value: 42 } }
}
bindings: {
key: "y"
value: { value: { int64_value: 42 } }
}
value: { bool_value: true }
}
}
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