Fix expansions that start from the end of another expansion (#839)

Do not free an expansion until its offset is *past* its size.
This means potentially freeing a nested stack of expansions
all at once.

Fixes #696

src/asm/lexer.c

@@ -736,7 +736,11 @@ static char const *readMacroArg(char name)
 static int peekInternal(uint8_t distance)
 {
 	for (struct Expansion *exp = lexerState->expansions; exp; exp = exp->parent) {
-		assert(exp->offset < exp->size);
+		/*
+		 * An expansion that has reached its end will have `exp->offset` == `exp->size`,
+		 * and `peekInternal` will continue with its parent
+		 */
+		assert(exp->offset <= exp->size);
 		if (distance < exp->size - exp->offset)
 			return exp->contents.unowned[exp->offset + distance];
 		distance -= exp->size - exp->offset;
@@ -870,16 +874,21 @@ static void shiftChar(void)
 
 	lexerState->macroArgScanDistance--;
 
+restart:
 	if (lexerState->expansions) {
 		/* Advance within the current expansion */
-		assert(lexerState->expansions->offset < lexerState->expansions->size);
+		assert(lexerState->expansions->offset <= lexerState->expansions->size);
 		lexerState->expansions->offset++;
-		if (lexerState->expansions->offset == lexerState->expansions->size) {
+		if (lexerState->expansions->offset > lexerState->expansions->size) {
-			/* When an expansion is done, free it and move up to its parent */
+			/*
+			 * When advancing would go past an expansion's end, free it,
+			 * move up to its parent, and try again to advance
+			 */
 			struct Expansion *exp = lexerState->expansions;
 
 			lexerState->expansions = lexerState->expansions->parent;
 			freeExpansion(exp);
+			goto restart;
 		}
 	} else {
 		/* Advance within the file contents */

test/asm/equs-newline.err

@@ -3,5 +3,6 @@ warning: equs-newline.asm(3): [-Wuser]
 while expanding symbol "ACT"
 warning: equs-newline.asm(3): [-Wuser]
     Second
+while expanding symbol "ACT"
 warning: equs-newline.asm(4): [-Wuser]
     Third

test/asm/equs-recursion.asm

@@ -1,6 +1,2 @@
 recurse EQUS "recurse"
 recurse
-
-; FIXME: also handle the following:
-; recurse EQUS "recurse"
-; recurse

test/asm/interpolation-recursion.asm

@@ -1,6 +1,2 @@
 recurse EQUS "\{recurse\}"
 {recurse}
-
-; FIXME: also handle the following:
-; recurse EQUS "\{recurse\}"
-; {recurse}

test/asm/rst.asm

@@ -16,12 +16,8 @@ SECTION "calls", ROM0[0]
 
 
 defRST: MACRO
-; FIXME: This is required, otherwise the lexer does not paste the two tokens
+	SECTION "rst\1", ROM0[$\1]
-ADDR equs "$\1"
-SECTION "rst\1", ROM0[ADDR]
-
 	rst\1:
-	PURGE ADDR
 ENDM
 	defRST 00
 	defRST 08

test/asm/test.sh

@@ -62,6 +62,7 @@ EOF
 	cat > quote\"file.err <<EOF
 warning: quote"file.asm(1): [-Wuser]
     quote"file.asm
+while expanding symbol "__FILE__"
 EOF
 fi
 

test/asm/unique-id.err

@@ -1,19 +1,27 @@
 warning: unique-id.asm(12) -> unique-id.asm::m(4): [-Wuser]
     _u1
+while expanding symbol "warn_unique"
 warning: unique-id.asm(12) -> unique-id.asm::m(5) -> unique-id.asm::m::REPT~1(6): [-Wuser]
     _u2
+while expanding symbol "warn_unique"
 warning: unique-id.asm(12) -> unique-id.asm::m(5) -> unique-id.asm::m::REPT~2(6): [-Wuser]
     _u3
+while expanding symbol "warn_unique"
 warning: unique-id.asm(12) -> unique-id.asm::m(8): [-Wuser]
     _u1
+while expanding symbol "warn_unique"
 warning: unique-id.asm(14) -> unique-id.asm::m(4): [-Wuser]
     _u4
+while expanding symbol "warn_unique"
 warning: unique-id.asm(14) -> unique-id.asm::m(5) -> unique-id.asm::m::REPT~1(6): [-Wuser]
     _u5
+while expanding symbol "warn_unique"
 warning: unique-id.asm(14) -> unique-id.asm::m(5) -> unique-id.asm::m::REPT~2(6): [-Wuser]
     _u6
+while expanding symbol "warn_unique"
 warning: unique-id.asm(14) -> unique-id.asm::m(8): [-Wuser]
     _u4
+while expanding symbol "warn_unique"
 FATAL: unique-id.asm(15):
     Macro argument '\@' not defined
 while expanding symbol "warn_unique"

test/link/rst.asm

@@ -14,12 +14,8 @@ SECTION "calls", ROM0[0]
 
 
 defRST: MACRO
-; FIXME: This is required, otherwise the lexer does not paste the two tokens
+	SECTION "rst\1", ROM0[$\1]
-ADDR equs "$\1"
-SECTION "rst\1", ROM0[ADDR]
-
 	rst\1:
-	PURGE ADDR
 ENDM
 	defRST 00
 	defRST 08