compiler: fix ??=, ||= and &&= logical assignment operators

When compiling logical assignment expressions, ensure that the rhs of the
assignment is not evaluated when the assignment condition is unfulfilled.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

compiler.c

@@ -1161,9 +1161,38 @@ uc_compiler_compile_expression(uc_compiler_t *compiler)
 static bool
 uc_compiler_compile_assignment(uc_compiler_t *compiler, uc_value_t *var)
 {
+	uc_chunk_t *chunk = uc_compiler_current_chunk(compiler);
 	uc_tokentype_t type = compiler->parser->curr.type;
+	size_t jmpz_off;
 
-	if (uc_compiler_parse_at_assignment_op(compiler)) {
+	if (type == TK_ASNULLISH) {
+		uc_compiler_parse_advance(compiler);
+		uc_compiler_emit_variable_rw(compiler, var, 0);
+		uc_compiler_emit_insn(compiler, 0, I_LNULL);
+		uc_compiler_emit_insn(compiler, 0, I_EQS);
+		jmpz_off = uc_compiler_emit_jmpz(compiler, 0);
+		uc_compiler_parse_precedence(compiler, P_ASSIGN);
+		uc_compiler_emit_variable_rw(compiler, var, type);
+		uc_compiler_set_jmpaddr(compiler, jmpz_off, chunk->count);
+	}
+	else if (type == TK_ASOR) {
+		uc_compiler_parse_advance(compiler);
+		uc_compiler_emit_variable_rw(compiler, var, 0);
+		uc_compiler_emit_insn(compiler, 0, I_NOT);
+		jmpz_off = uc_compiler_emit_jmpz(compiler, 0);
+		uc_compiler_parse_precedence(compiler, P_ASSIGN);
+		uc_compiler_emit_variable_rw(compiler, var, type);
+		uc_compiler_set_jmpaddr(compiler, jmpz_off, chunk->count);
+	}
+	else if (type == TK_ASAND) {
+		uc_compiler_parse_advance(compiler);
+		uc_compiler_emit_variable_rw(compiler, var, 0);
+		jmpz_off = uc_compiler_emit_jmpz(compiler, 0);
+		uc_compiler_parse_precedence(compiler, P_ASSIGN);
+		uc_compiler_emit_variable_rw(compiler, var, type);
+		uc_compiler_set_jmpaddr(compiler, jmpz_off, chunk->count);
+	}
+	else if (uc_compiler_parse_at_assignment_op(compiler)) {
 		uc_compiler_parse_advance(compiler);
 		uc_compiler_parse_precedence(compiler, P_ASSIGN);
 		uc_compiler_emit_variable_rw(compiler, var, type);

tests/custom/00_syntax/25_and_or_assignment

@@ -53,3 +53,33 @@ expression result if the lhs is falsy.
 	printf("%.J\n", [ x, y, z ]);
 %}
 -- End --
+
+
+3. Ensure that the assignment value expression is not evaluated if the
+assignment condition is false.
+
+-- Expect stdout --
+[
+	0,
+	0,
+	0
+]
+-- End --
+
+-- Testcase --
+{%
+	a = 0;
+	b = 0;
+	c = 0;
+
+	x = false;
+	y = false;
+	z = true;
+
+	x ??= a++;
+	y &&= b++;
+	z ||= c++;
+
+	printf("%.J\n", [ a, b, c ]);
+%}
+-- End --