Update error messages

compiler/desugared/linting.mli

@@ -0,0 +1,19 @@
+(* This file is part of the Catala compiler, a specification language for tax
+   and social benefits computation rules. Copyright (C) 2023 Inria, contributor:
+   Denis Merigoux <denis.merigoux@inria.fr>
+
+   Licensed under the Apache License, Version 2.0 (the "License"); you may not
+   use this file except in compliance with the License. You may obtain a copy of
+   the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+   License for the specific language governing permissions and limitations under
+   the License. *)
+
+val lint_program : Ast.program -> unit
+(** Performs various lints on the program, displaying warnings to help the
+    developer improve the code. *)

tests/test_enum/bad/missing_case.catala_en

@@ -18,6 +18,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
+[WARNING] The constructor "Case3" of enumeration "E" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_enum/bad/missing_case.catala_en:7.5-10:
+└─┐
+7 │   -- Case3
+  │      ‾‾‾‾‾
+  └─ Article
 [ERROR] The constructor Case3 of enum E is missing from this pattern matching
 
 ┌─⯈ tests/test_enum/bad/missing_case.catala_en:14.24-16.21:

tests/test_proof/bad/enums-empty.catala_en

@@ -23,6 +23,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples 
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/bad/enums-empty.catala_en:7.6-7:
+└─┐
+7 │    -- C content boolean
+  │       ‾
+  └─ Test
 [ERROR] [A.x] This variable might return an empty error:
 ┌─⯈ tests/test_proof/bad/enums-empty.catala_en:15.10-11:
 └──┐

tests/test_proof/bad/enums-nonbool-empty.catala_en

@@ -21,6 +21,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/bad/enums-nonbool-empty.catala_en:5.6-7:
+└─┐
+5 │    -- C content boolean
+  │       ‾
+  └─ Test
 [ERROR] [A.x] This variable might return an empty error:
 ┌─⯈ tests/test_proof/bad/enums-nonbool-empty.catala_en:13.10-11:
 └──┐

tests/test_proof/bad/enums-nonbool-overlap.catala_en

@@ -21,6 +21,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/bad/enums-nonbool-overlap.catala_en:5.6-7:
+└─┐
+5 │    -- C content boolean
+  │       ‾
+  └─ Test
 [ERROR] [A.x] At least two exceptions overlap for this variable:
 ┌─⯈ tests/test_proof/bad/enums-nonbool-overlap.catala_en:13.10-11:
 └──┐

tests/test_proof/bad/enums-overlap.catala_en

@@ -23,6 +23,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples 
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/bad/enums-overlap.catala_en:7.6-7:
+└─┐
+7 │    -- C content boolean
+  │       ‾
+  └─ Test
 [ERROR] [A.x] At least two exceptions overlap for this variable:
 ┌─⯈ tests/test_proof/bad/enums-overlap.catala_en:15.10-11:
 └──┐

tests/test_proof/bad/enums_inj-empty.catala_en

@@ -16,6 +16,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples 
+[WARNING] The constructor "C2" of enumeration "E" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/bad/enums_inj-empty.catala_en:6.5-7:
+└─┐
+6 │   -- C2
+  │      ‾‾
+  └─ Article
 [ERROR] [A.y] This variable might return an empty error:
 ┌─⯈ tests/test_proof/bad/enums_inj-empty.catala_en:10.10-11:
 └──┐

tests/test_proof/good/enums-arith.catala_en

@@ -21,5 +21,12 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples 
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/good/enums-arith.catala_en:5.6-7:
+└─┐
+5 │    -- C content boolean
+  │       ‾
+  └─ Test
 [RESULT] No errors found during the proof mode run.
 ```

tests/test_proof/good/enums-nonbool.catala_en

@@ -21,5 +21,12 @@ scope A:
 
 ```catala-test-inline
 $ catala Proof --disable_counterexamples
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/good/enums-nonbool.catala_en:5.6-7:
+└─┐
+5 │    -- C content boolean
+  │       ‾
+  └─ Test
 [RESULT] No errors found during the proof mode run.
 ```

tests/test_proof/good/enums.catala_en

@@ -20,5 +20,12 @@ scope A:
 ```
 ```catala-test-inline
 $ catala Proof --disable_counterexamples 
+[WARNING] The constructor "C" of enumeration "T" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_proof/good/enums.catala_en:5.6-7:
+└─┐
+5 │    -- C content boolean
+  │       ‾
+  └─ Test
 [RESULT] No errors found during the proof mode run.
 ```

tests/test_scope/good/nothing.catala_en

@@ -7,6 +7,13 @@ declaration scope Foo2:
 
 ```catala-test-inline
 $ catala Scalc -s Foo2 -O -t
+[WARNING] The variable "bar" is declared but never defined in scope "Foo2"; did you forget something?
+
+┌─⯈ tests/test_scope/good/nothing.catala_en:5.9-12:
+└─┐
+5 │   output bar content integer
+  │          ‾‾‾
+  └─ Test
 let Foo2_3 (Foo2_in_2: Foo2_in {}) =
   decl temp_bar_4 : any;
   temp_bar_4 = dead_value_1;

tests/test_scope/good/scope_call.catala_en

@@ -26,6 +26,20 @@ scope Foo:
 
 ```catala-test-inline
 $ catala interpret -s Foo
+[WARNING] The field "z2" of struct "Test" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_scope/good/scope_call.catala_en:3.9-11:
+└─┐
+3 │     data z2 content integer
+  │          ‾‾
+
+[WARNING] The field "z3" of struct "Test" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_scope/good/scope_call.catala_en:4.9-11:
+└─┐
+4 │     data z3 content integer
+  │          ‾‾
+
 [RESULT] Computation successful! Results:
 [RESULT] example = -7
 ```

tests/test_struct/bad/nested.catala_en

@@ -14,6 +14,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
+[WARNING] The constructor "Rec" of enumeration "E" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/bad/nested.catala_en:6.5-8:
+└─┐
+6 │   -- Rec content E
+  │      ‾‾‾
+  └─ Article
 [ERROR] The type E is defined using itself, which is forbidden since Catala does not provide recursive types
 
 ┌─⯈ tests/test_struct/bad/nested.catala_en:6.17-18:

tests/test_struct/bad/nested2.catala_en

@@ -15,6 +15,27 @@ declaration scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
+[WARNING] The field "x" of struct "S" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/bad/nested2.catala_en:5.7-8:
+└─┐
+5 │   data x content E
+  │        ‾
+  └─ Article
+[WARNING] The field "y" of struct "S" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/bad/nested2.catala_en:6.7-8:
+└─┐
+6 │   data y content integer
+  │        ‾
+  └─ Article
+[WARNING] The enumeration "E" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/bad/nested2.catala_en:8.24-25:
+└─┐
+8 │ declaration enumeration E:
+  │                         ‾
+  └─ Article
 [ERROR] Cyclic dependency detected between types!
 
 Cycle type S, declared:

tests/test_struct/bad/wrong_qualified_field.catala_en

@@ -19,7 +19,7 @@ scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
-[ERROR] Field g does not belong to structure Foo, but to Bar
+[ERROR] Field "g" does not belong to structure "Foo", but to "Bar"
 
 ┌─⯈ tests/test_struct/bad/wrong_qualified_field.catala_en:17.22-29:
 └──┐

tests/test_struct/good/ambiguous_fields.catala_en

@@ -18,5 +18,12 @@ scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
+[WARNING] The field "f" of struct "Bar" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/good/ambiguous_fields.catala_en:8.7-8:
+└─┐
+8 │   data f content integer
+  │        ‾
+  └─ Article
 [RESULT] Computation successful!
 ```

tests/test_struct/good/same_name_fields.catala_en

@@ -18,6 +18,13 @@ scope A:
 
 ```catala-test-inline
 $ catala Interpret -s A
+[WARNING] The field "f" of struct "Bar" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_struct/good/same_name_fields.catala_en:8.7-8:
+└─┐
+8 │   data f content integer
+  │        ‾
+  └─ Article
 [RESULT] Computation successful! Results:
 [RESULT] x = Foo { "f"= 1 }
 [RESULT] y = 1

tests/test_typing/bad/err3.catala_en

@@ -12,6 +12,13 @@ scope S:
 
 ```catala-test-inline
 $ catala Typecheck
+[WARNING] The constructor "Dec" of enumeration "Enum" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:4.5-8:
+└─┐
+4 │   -- Dec content decimal
+  │      ‾‾‾
+
 [ERROR] Error during typechecking, incompatible types:
 --> integer
 --> decimal
@@ -43,6 +50,13 @@ Re-putting the same check again, to ensure that the `Typecheck` and `ocaml` subc
 
 ```catala-test-inline
 $ catala ocaml
+[WARNING] The constructor "Dec" of enumeration "Enum" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:4.5-8:
+└─┐
+4 │   -- Dec content decimal
+  │      ‾‾‾
+
 [ERROR] Error during typechecking, incompatible types:
 --> integer
 --> decimal

tests/test_typing/bad/err4.catala_en

@@ -10,6 +10,34 @@ Should be "catala Typecheck", see test err3
 
 ```catala-test-inline
 $ catala ocaml
+[WARNING] The field "i" of struct "Structure" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:8.7-8:
+└─┐
+8 │   data i content integer
+  │        ‾
+
+[WARNING] The field "e" of struct "Structure" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:9.7-8:
+└─┐
+9 │   data e content Enum
+  │        ‾
+
+[WARNING] The constructor "Dec" of enumeration "Enum" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:4.5-8:
+└─┐
+4 │   -- Dec content decimal
+  │      ‾‾‾
+
+[WARNING] The constructor "Dat" of enumeration "Enum" is never used; maybe it's unnecessary?
+
+┌─⯈ tests/test_typing/bad/common.catala_en:5.5-8:
+└─┐
+5 │   -- Dat content date
+  │      ‾‾‾
+
 [ERROR] Error during typechecking, incompatible types:
 --> Enum
 --> Structure