From 75105016f72a862ff30895b6cf4a8e5be63d1bd1 Mon Sep 17 00:00:00 2001
From: Rangi42 <remy.oukaour+rangi42@gmail.com>
Date: Wed, 6 Mar 2024 15:53:01 -0500
Subject: [PATCH] Make sure that parsed subexpressions are fully defined

We were not initializing some expressions, and they were using
the values of the previous expressions instead. This just so
happened to not crash the tests, and to sometimes even give valid
results (although `BANK()` of a non-label symbol being $4B4E4142,
the ASCII balue of "BANK", was something we missed).
---
 src/asm/parser.y  |  5 +++--
 src/asm/rpn.cpp   | 11 +++++++----
 test/asm/bank.out |  2 +-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/asm/parser.y b/src/asm/parser.y
index a88f2a7d..cd120fd5 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -1676,12 +1676,13 @@ sectattrs:
 		$$.bank = -1;
 	}
 	| sectattrs T_COMMA T_OP_ALIGN T_LBRACK align_spec T_RBRACK {
+		$$ = $1;
 		$$.alignment = $5.alignment;
 		$$.alignOfs = $5.alignOfs;
 	}
 	| sectattrs T_COMMA T_OP_BANK T_LBRACK uconst T_RBRACK {
-		// We cannot check the validity of this now
-		$$.bank = $5;
+		$$ = $1;
+		$$.bank = $5; // We cannot check the validity of this yet
 	}
 ;
 
diff --git a/src/asm/rpn.cpp b/src/asm/rpn.cpp
index bad0d5c1..afac5c37 100644
--- a/src/asm/rpn.cpp
+++ b/src/asm/rpn.cpp
@@ -24,6 +24,7 @@
 
 // Init a RPN expression
 static void initExpression(Expression &expr) {
+	expr.val = 0;
 	expr.reason = nullptr;
 	expr.isKnown = true;
 	expr.isSymbol = false;
@@ -68,13 +69,14 @@ void rpn_Number(Expression &expr, uint32_t val) {
 }
 
 void rpn_Symbol(Expression &expr, char const *symName) {
+	initExpression(expr);
+
 	Symbol *sym = sym_FindScopedSymbol(symName);
 
 	if (sym_IsPC(sym) && !sect_GetSymbolSection()) {
 		error("PC has no value outside a section\n");
-		rpn_Number(expr, 0);
+		expr.val = 0;
 	} else if (!sym || !sym->isConstant()) {
-		initExpression(expr);
 		expr.isSymbol = true;
 
 		if (sym_IsPC(sym))
@@ -89,7 +91,7 @@ void rpn_Symbol(Expression &expr, char const *symName) {
 		*ptr++ = RPN_SYM;
 		memcpy(ptr, sym->name, nameLen);
 	} else {
-		rpn_Number(expr, sym_GetConstantValue(symName));
+		expr.val = sym_GetConstantValue(symName);
 	}
 }
 
@@ -120,6 +122,7 @@ void rpn_BankSymbol(Expression &expr, char const *symName) {
 	initExpression(expr);
 	if (sym && !sym->isLabel()) {
 		error("BANK argument must be a label\n");
+		expr.val = 1;
 	} else {
 		sym = sym_Ref(symName);
 		assert(sym); // If the symbol didn't exist, it should have been created
@@ -345,13 +348,13 @@ static int32_t tryConstMask(Expression const &lhs, Expression const &rhs) {
 void rpn_BinaryOp(
     enum RPNCommand op, Expression &expr, const Expression &src1, const Expression &src2
 ) {
+	initExpression(expr);
 	expr.isSymbol = false;
 	int32_t constMaskVal;
 
 	// First, check if the expression is known
 	expr.isKnown = src1.isKnown && src2.isKnown;
 	if (expr.isKnown) {
-		initExpression(expr); // Init the expression to something sane
 
 		// If both expressions are known, just compute the value
 		uint32_t uleft = src1.val, uright = src2.val;
diff --git a/test/asm/bank.out b/test/asm/bank.out
index c1a51888..7335b56b 100644
--- a/test/asm/bank.out
+++ b/test/asm/bank.out
@@ -12,4 +12,4 @@ WRAMX_ok (WRAMX): $7 == $7
 WRAMX_bad (WRAMX): $0 == $0
 OAM_ok (OAM): $0 == $0
 HRAM_ok (HRAM): $0 == $0
-def_sect: $4B4E4142
+def_sect: $1