feat(analyzer): diagnose modification of for-loop bounds

crates/analyzer/src/analyzer.rs

@@ -3,6 +3,7 @@ use crate::attribute_table;
 use crate::comb_loop_detect;
 use crate::conv::{Context, Conv};
 use crate::definition_table;
+use crate::dynamic_for_check;
 use crate::generic_inference_table;
 use crate::handlers::*;
 use crate::ir::{Ir, IrResult};
@@ -266,6 +267,7 @@ impl Analyzer {
 
         ret.append(&mut symbol_table::check_unused_variable());
         ret.append(&mut symbol_table::check_wavedrom());
+        ret.append(&mut dynamic_for_check::check(ir));
         ret.append(&mut comb_loop_detect::check(ir));
 
         ret

crates/analyzer/src/analyzer_error.rs

@@ -740,6 +740,23 @@ pub enum AnalyzerError {
         token_source: TokenSource,
     },
 
+    #[diagnostic(
+        severity(Warning),
+        code(mutable_for_bound),
+        help("move the assignment outside the loop or iterate over a separate, stable bound; this will become an error in a future release"),
+        url("https://doc.veryl-lang.org/book/07_appendix/02_semantic_error.html#{}", self.code().unwrap())
+    )]
+    #[error(
+        "for-loop continuation bound is modified by the loop body, so backends may execute different iteration counts"
+    )]
+    MutableForBound {
+        #[source_code]
+        input: MultiSources,
+        #[label("Warning location")]
+        error_location: SourceSpan,
+        token_source: TokenSource,
+    },
+
     #[diagnostic(
         severity(Error),
         code(invalid_for_step),
@@ -2076,6 +2093,7 @@ impl AnalyzerError {
             AnalyzerError::MissingTri { input, .. } => input,
             AnalyzerError::MixedFunctionArgument { input, .. } => input,
             AnalyzerError::MixedStructUnionMember { input, .. } => input,
+            AnalyzerError::MutableForBound { input, .. } => input,
             AnalyzerError::MultipleAssignment { input, .. } => input,
             AnalyzerError::MultipleDefault { input, .. } => input,
             AnalyzerError::NonConstantSelectWidth { input, .. } => input,
@@ -2197,6 +2215,7 @@ impl AnalyzerError {
             AnalyzerError::MissingTri { token_source, .. } => *token_source,
             AnalyzerError::MixedFunctionArgument { token_source, .. } => *token_source,
             AnalyzerError::MixedStructUnionMember { token_source, .. } => *token_source,
+            AnalyzerError::MutableForBound { token_source, .. } => *token_source,
             AnalyzerError::MultipleAssignment { token_source, .. } => *token_source,
             AnalyzerError::MultipleDefault { token_source, .. } => *token_source,
             AnalyzerError::PrivateMember { token_source, .. } => *token_source,
@@ -2638,6 +2657,13 @@ impl AnalyzerError {
             token_source: token.source(),
         }
     }
+    pub fn mutable_for_bound(token: &TokenRange) -> Self {
+        AnalyzerError::MutableForBound {
+            input: source(token),
+            error_location: token.into(),
+            token_source: token.source(),
+        }
+    }
     pub fn invalid_for_step(cause: InvalidForStepKind, token: &TokenRange) -> Self {
         AnalyzerError::InvalidForStep {
             cause,

crates/analyzer/src/attribute.rs

@@ -196,6 +196,7 @@ struct Pattern {
     pub missing_reset_statement: StrId,
     pub unused_variable: StrId,
     pub unassign_variable: StrId,
+    pub mutable_for_bound: StrId,
     pub enum_encoding: StrId,
     pub sequential: StrId,
     pub onehot: StrId,
@@ -231,6 +232,7 @@ impl Pattern {
             missing_reset_statement: resource_table::insert_str("missing_reset_statement"),
             unused_variable: resource_table::insert_str("unused_variable"),
             unassign_variable: resource_table::insert_str("unassign_variable"),
+            mutable_for_bound: resource_table::insert_str("mutable_for_bound"),
             enum_encoding: resource_table::insert_str("enum_encoding"),
             sequential: resource_table::insert_str("sequential"),
             onehot: resource_table::insert_str("onehot"),
@@ -348,6 +350,9 @@ impl TryFrom<&veryl_parser::veryl_grammar_trait::Attribute> for Attribute {
                         x if x == pat.unassign_variable => {
                             Ok(Attribute::Allow(AllowItem::UnassignVariable))
                         }
+                        x if x == pat.mutable_for_bound => {
+                            Ok(Attribute::Allow(AllowItem::MutableForBound))
+                        }
                         _ => Err(err),
                     }
                 } else {
@@ -536,6 +541,7 @@ pub enum AllowItem {
     MissingResetStatement,
     UnusedVariable,
     UnassignVariable,
+    MutableForBound,
 }
 
 impl AllowItem {
@@ -558,6 +564,7 @@ impl fmt::Display for AllowItem {
             AllowItem::MissingResetStatement => "missing_reset_statement",
             AllowItem::UnusedVariable => "unused_variable",
             AllowItem::UnassignVariable => "unassign_variable",
+            AllowItem::MutableForBound => "mutable_for_bound",
         };
         text.fmt(f)
     }