From: Rico Tzschichholz <ricotz@ubuntu.com>
Date: Mon, 17 Feb 2020 16:43:24 +0000 (+0100)
Subject: codegen: Don't initialize stack-allocated array with local-constant length
X-Git-Tag: 0.47.92~22
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a0bb129e5a2e8580eb272d9a68ba054e7b170dba;p=thirdparty%2Fvala.git

codegen: Don't initialize stack-allocated array with local-constant length

Fixes https://gitlab.gnome.org/GNOME/vala/issues/910
---

diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 52bc6d930..4336fb37f 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -2547,8 +2547,10 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 
 				// try to initialize uninitialized variables
 				// initialization not necessary for variables stored in closure
-				cvar.initializer = default_value_for_type (local.variable_type, true);
-				cvar.init0 = true;
+				if (is_init_allowed (local.variable_type)) {
+					cvar.initializer = default_value_for_type (local.variable_type, true);
+					cvar.init0 = true;
+				}
 
 				ccode.add_declaration (get_ccode_name (local.variable_type), cvar);
 			}
@@ -3802,7 +3804,7 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 			}
 		} else {
 			var cvar = new CCodeVariableDeclarator (local.name, null, get_ccode_declarator_suffix (local.variable_type));
-			if (init) {
+			if (init && is_init_allowed (local.variable_type)) {
 				cvar.initializer = default_value_for_type (local.variable_type, true, on_error);
 				cvar.init0 = true;
 			}
@@ -6350,6 +6352,17 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 		return true;
 	}
 
+	public bool is_init_allowed (DataType type) {
+		unowned ArrayType? array_type = type as ArrayType;
+		if (array_type != null && array_type.inline_allocated
+		   && array_type.fixed_length) {
+		   unowned Constant? c = array_type.length.symbol_reference as Constant;
+		   // our local constants are not actual constants in C
+		   return (c == null || !(c.parent_symbol is Block));
+		}
+		return true;
+	}
+
 	public CCodeDeclaratorSuffix? get_ccode_declarator_suffix (DataType type) {
 		var array_type = type as ArrayType;
 		if (array_type != null) {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8079e335a..f683d18c7 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -75,6 +75,7 @@ TESTS = \
 	arrays/cast-silent-invalid.test \
 	arrays/class-field-length-cname.vala \
 	arrays/expression-bracket.test \
+	arrays/fixed-length-init0-not-allowed.vala \
 	arrays/field-global-length-cname.vala \
 	arrays/fixed-length-concat-invalid.test \
 	arrays/fixed-length-non-const.test \
diff --git a/tests/arrays/fixed-length-init0-not-allowed.vala b/tests/arrays/fixed-length-init0-not-allowed.vala
new file mode 100644
index 000000000..932f011b3
--- /dev/null
+++ b/tests/arrays/fixed-length-init0-not-allowed.vala
@@ -0,0 +1,13 @@
+void main () {
+	const int FOO = 4;
+
+	char bar[FOO] = { 'f', 'o', 'o', '\0' };
+	assert ((string) bar == "foo");
+
+	char baz[FOO];
+	baz[0] = 'f';
+	baz[1] = 'o';
+	baz[2] = 'o';
+	baz[3] = '\0';
+	assert ((string) baz == "foo");
+}