chore: error on false constraint (#5890)

# Description

## Problem\*

Report a bug during compilation when a constraint is false

## Summary\*

It is done in acir-gen which ensures that all side effects are resolved.


## Additional Context

The reported bug does not fail the compilation, because it will mess
around compile/run-time failures and also for the Noir tests. We want a
consistent handling of assert, whether it fails at compile-time,
run-time, or test-time.

## Documentation\*

Check one:
- [X] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [X] I have tested the changes locally.
- [X] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: jfecher <jake@aztecprotocol.com>

compiler/noirc_evaluator/src/errors.rs

@@ -88,6 +88,7 @@ impl From<SsaReport> for FileDiagnostic {
                     InternalBug::IndependentSubgraph { call_stack } => {
                         ("There is no path from the output of this brillig call to either return values or inputs of the circuit, which creates an independent subgraph. This is quite likely a soundness vulnerability".to_string(),call_stack)
                     }
+                    InternalBug::AssertFailed { call_stack } => ("As a result, the compiled circuit is ensured to fail. Other assertions may also fail during execution".to_string(), call_stack)
                 };
                 let call_stack = vecmap(call_stack, |location| location);
                 let file_id = call_stack.last().map(|location| location.file).unwrap_or_default();
@@ -111,6 +112,8 @@ pub enum InternalWarning {
 pub enum InternalBug {
     #[error("Input to brillig function is in a separate subgraph to output")]
     IndependentSubgraph { call_stack: CallStack },
+    #[error("Assertion is always false")]
+    AssertFailed { call_stack: CallStack },
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Error)]

compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/acir_variable.rs

@@ -2,7 +2,7 @@ use super::big_int::BigIntContext;
 use super::generated_acir::{BrilligStdlibFunc, GeneratedAcir, PLACEHOLDER_BRILLIG_INDEX};
 use crate::brillig::brillig_gen::brillig_directive;
 use crate::brillig::brillig_ir::artifact::GeneratedBrillig;
-use crate::errors::{InternalError, RuntimeError, SsaReport};
+use crate::errors::{InternalBug, InternalError, RuntimeError, SsaReport};
 use crate::ssa::acir_gen::{AcirDynamicArray, AcirValue};
 use crate::ssa::ir::dfg::CallStack;
 use crate::ssa::ir::types::Type as SsaType;
@@ -126,6 +126,8 @@ pub(crate) struct AcirContext<F: AcirField> {
     big_int_ctx: BigIntContext,
 
     expression_width: ExpressionWidth,
+
+    pub(crate) warnings: Vec<SsaReport>,
 }
 
 impl<F: AcirField> AcirContext<F> {
@@ -518,6 +520,12 @@ impl<F: AcirField> AcirContext<F> {
             self.mark_variables_equivalent(lhs, rhs)?;
             return Ok(());
         }
+        if diff_expr.is_const() {
+            // Constraint is always false
+            self.warnings.push(SsaReport::Bug(InternalBug::AssertFailed {
+                call_stack: self.get_call_stack(),
+            }));
+        }
 
         self.acir_ir.assert_is_zero(diff_expr);
         if let Some(payload) = assert_message {

compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs

@@ -453,6 +453,7 @@ impl<'a> Context<'a> {
         }
 
         warnings.extend(return_warnings);
+        warnings.extend(self.acir_context.warnings.clone());
 
         // Add the warnings from the alter Ssa passes
         Ok(self.acir_context.finish(input_witness, return_witnesses, warnings))