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-rw-r--r--AGENTS/ARCH.md3
-rw-r--r--AGENTS/CONVENTIONS.md19
-rw-r--r--AGENTS/EXTENDING.md3
-rw-r--r--AGENTS/PITFALLS.md8
-rw-r--r--AGENTS/SUBSYSTEMS.md2
5 files changed, 23 insertions, 12 deletions
diff --git a/AGENTS/ARCH.md b/AGENTS/ARCH.md
index 4fab3ee..ffde252 100644
--- a/AGENTS/ARCH.md
+++ b/AGENTS/ARCH.md
@@ -264,9 +264,10 @@ do not modify the real release for local verification.
| `lib/Parser/ParserExpression.cc`, `ParserControlFlow.cc` | Expressions/designators and control-flow statement parsing (including ordered CASE branches) |
| `lib/Parser/ParserFunction.cc` | FUNCTION/PROCEDURE/CALL/RETURN + parameter-list parsing |
| `lib/Parser/ParserFile.cc` | OPENFILE/READFILE/WRITEFILE/CLOSEFILE parsing |
-| `lib/Parser/ParserType.cc` | Type names, variable/array declarations, TYPE/ENDTYPE and CLASS/ENDCLASS declarations, shared field parsing, SET/DEFINE reserved stubs |
+| `lib/Parser/ParserType.cc` | Type names, variable/array/constant declarations, TYPE/ENDTYPE and CLASS/ENDCLASS declarations, shared field parsing, SET/DEFINE reserved stubs |
| `lib/CodeGen/CodeGen.cc` | Initialization, symbols, call arguments and main() compilation |
| `lib/CodeGen/ExpressionGen.cc`, `StatementGen.cc`, `ControlFlowGen.cc` | Expression/statement dispatch and control-flow emission |
+| `lib/CodeGen/ConstantGen.cc` | Literal constants, declaration conflicts and lexical binding restoration |
| `lib/CodeGen/ValueTypeGen.cc`, `OutputGen.cc`, `Builtins.h` | Expression typing, coercion/declarations, scalar output and the shared builtin table |
| `lib/CodeGen/Designator.cc`, `TypeCheckGen.cc` | TYPE pre-pass and lvalue access; type admission and user-kind binary operators |
| `lib/CodeGen/CTypeGen.cc` | CodeGen methods for native C scalar conversions, casts, arithmetic and input/output |
diff --git a/AGENTS/CONVENTIONS.md b/AGENTS/CONVENTIONS.md
index 5b16242..93c6f24 100644
--- a/AGENTS/CONVENTIONS.md
+++ b/AGENTS/CONVENTIONS.md
@@ -93,12 +93,19 @@ only `realloc`); `CodeGen` also keeps its own `MallocFunc` for the char→STRING
and INPUT STRING buffers — declared in `SetupExternalFunctions`, never fetched with a
bare `getFunction("malloc")`.
-**One flat symbol namespace, one table.** `Symbols` (name → `SymbolInfo{Storage,
-TypeName, IsArray}`) in CodeGen is the only symbol table; register through
-`registerSymbol()` (or directly, as `FunctionGen::createArgumentAllocas` does for
-parameters) and read storage through `getNamedValue()`/`getSymbolInfo()`. There is no
-scope stack. `FunctionGen` saves/clears/restores the table around a function body, but
-`ArrayHandler::ArrayTable` is *not* scoped (see `PITFALLS.md`).
+**One symbol namespace, one table.** `Symbols` (name → `SymbolInfo{Storage,
+TypeName, IsArray, ConstantValue, ScopeID}`) in CodeGen is the only symbol table.
+A non-null ConstantValue denotes a read-only CONSTANT with no Storage. Read it
+through `emitExpr`; all writable/address-taking paths must reject it through
+`requireWritable`. Register variables through `registerSymbol()` (parameters are
+also bound directly by FunctionGen). `prepareSymbolDeclaration` diagnoses
+same-scope conflicts involving constants before declaration emission. Unique
+scope IDs distinguish sibling blocks; `emitScopedBlock` restores only bindings
+introduced by constants or hiding constants, preserving other variables' existing
+function-wide visibility. FunctionGen saves/restores Symbols and inherits only
+previously visible top-level constants (ScopeID 0). CodeGen isolates constant
+scope bookkeeping and array metadata around each function body. Arrays also
+restore metadata at control-flow block exits.
**Dispatch is by `dynamic_cast` chain, not virtual methods.** `CodeGen::emitStmt` and
`emitExpr` walk a linear if-chain of casts. **A statement type missing from the chain is
diff --git a/AGENTS/EXTENDING.md b/AGENTS/EXTENDING.md
index d03c088..5e104c8 100644
--- a/AGENTS/EXTENDING.md
+++ b/AGENTS/EXTENDING.md
@@ -9,7 +9,8 @@ unique_ptr children, move ctor, raw-ptr getters) → `ParseXxx` in
the matching `Parser*.cc` file + branch in `ParseStatementImpl` (block statements parse their body with
`ParseBlock({terminator tokens})`; control-flow parsers live in `ParserControlFlow.cc`; comma-separated expression lists use
`ParseExprList(close, allowEmpty)`; add the new statement's leading keyword to
-`syncToStatementStart`) → `dynamic_cast` branch in `CodeGen::emitStmt`. Guard every
+`syncToStatementStart`) → `dynamic_cast` branch in `CodeGen::emitStmt`. Emit statement bodies through `emitScopedBlock`
+so constants cannot escape their lexical block. Guard every
fall-through branch in control-flow codegen with
`if (!Builder->GetInsertBlock()->hasTerminator())` — a RETURN in the body may have
already terminated the block.
diff --git a/AGENTS/PITFALLS.md b/AGENTS/PITFALLS.md
index 93564f1..58934ce 100644
--- a/AGENTS/PITFALLS.md
+++ b/AGENTS/PITFALLS.md
@@ -35,9 +35,11 @@ test programs.
- **`getExprTypeInfo` returns nullptr** for expressions it can't classify (null-check it
at any new call site) and internally defaults to INTEGER for arithmetic binaries and
unknown-function calls; OUTPUT reports an error for a nullptr result.
+- **CONSTANT** accepts only literals (including negative numeric literals), never expressions or other names. Constants have lexical block scope and may shadow outer names; bindings hiding constants are restored on block exit too. Only previously declared top-level constants are inherited by functions. Constants have no writable storage: assignment, INPUT, READFILE targets, FOR variables, BYREF and address-of are rejected.
- **CASE OF** reads its selector once and tests expression labels in source order, with inclusive TO ranges and an optional final OTHERWISE. Label headers occupy their own source line; bodies may begin after the colon or on subsequent lines. Comparisons reuse ordinary operator rules; records and whole arrays are unsupported.
-- The lexer emits no newline tokens; the grammar is purely keyword-delimited. Bare
- `RETURN` is recognized before block terminators, including CATCH and ENDTRY.
+- The lexer emits no newline tokens; most grammar is keyword-delimited, while CASE
+ uses token line information to recognize labels. Bare `RETURN` is recognized
+ before block terminators and the next CASE label.
- `verifyModule` runs at the end of `compile()`; invalid modules make the driver
exit non-zero without writing IR.
- The FOR loop variable must be pre-DECLAREd as INTEGER; FOR reuses that alloca. The
@@ -101,7 +103,7 @@ test programs.
## Not implemented (9618 features)
-CONSTANT, SET types (`SET`/`DEFINE` are reserved with dedicated errors),
+SET types (`SET`/`DEFINE` are reserved with dedicated errors),
random files (OPENFILE...FOR RANDOM/SEEK/GETRECORD/PUTRECORD — TYPE is done, so these
are unblocked now; the RANDOM keyword is reserved and gives a dedicated parse error),
DATE, INPUT into array elements, string escape sequences,
diff --git a/AGENTS/SUBSYSTEMS.md b/AGENTS/SUBSYSTEMS.md
index f693b1c..c553f8e 100644
--- a/AGENTS/SUBSYSTEMS.md
+++ b/AGENTS/SUBSYSTEMS.md
@@ -34,7 +34,7 @@ map (`FunctionGen::getSignature`); `CodeGen::marshalCallArgs` dispatches call ar
on those *declared* `ParamSig`s, and `getExprTypeInfo` reads return types from the same
map. Top-level prototypes are pre-registered at the start of `compile()` (after the
TYPE pre-pass), so calls may precede definitions; calling a name with no signature is a
-compile error (no extern is fabricated). Body emission is inverted: CodeGen injects a
+compile error (no extern is fabricated). Functions inherit previously declared top-level CONSTANT values; local constants use the same Symbols table with lexical binding restoration. Body emission is inverted: CodeGen injects a
`StmtEmitter` callback, and must restore its own insert point (and the exchanged
ArrayTable) afterwards.