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translate-c: comma operator should introduce a new scope

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This prevents inadvertent side-effects when an expression is not evaluated
due to boolean short-circuiting

Fixes #7989
This commit is contained in:
Evan Haas 2021-02-11 09:43:30 -08:00 committed by Veikka Tuominen
parent 61bcac108c
commit d98f09e4f6
3 changed files with 49 additions and 29 deletions
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33
src/translate_c.zig
View File

@ -1438,30 +1438,25 @@ fn transBinaryOperator(
switch (op) {
.Assign => return try transCreateNodeAssign(rp, scope, result_used, stmt.getLHS(), stmt.getRHS()),
.Comma => {
const block_scope = try scope.findBlockScope(rp.c);
const expr = block_scope.base.parent == scope;
const lparen = if (expr) try appendToken(rp.c, .LParen, "(") else undefined;
var block_scope = try Scope.Block.init(rp.c, scope, true);
const lparen = try appendToken(rp.c, .LParen, "(");
const lhs = try transExpr(rp, &block_scope.base, stmt.getLHS(), .unused, .r_value);
try block_scope.statements.append(lhs);
const rhs = try transExpr(rp, &block_scope.base, stmt.getRHS(), .used, .r_value);
if (expr) {
_ = try appendToken(rp.c, .Semicolon, ";");
const break_node = try transCreateNodeBreak(rp.c, block_scope.label, rhs);
try block_scope.statements.append(&break_node.base);
const block_node = try block_scope.complete(rp.c);
const rparen = try appendToken(rp.c, .RParen, ")");
const grouped_expr = try rp.c.arena.create(ast.Node.GroupedExpression);
grouped_expr.* = .{
.lparen = lparen,
.expr = block_node,
.rparen = rparen,
};
return maybeSuppressResult(rp, scope, result_used, &grouped_expr.base);
} else {
return maybeSuppressResult(rp, scope, result_used, rhs);
}
_ = try appendToken(rp.c, .Semicolon, ";");
const break_node = try transCreateNodeBreak(rp.c, block_scope.label, rhs);
try block_scope.statements.append(&break_node.base);
const block_node = try block_scope.complete(rp.c);
const rparen = try appendToken(rp.c, .RParen, ")");
const grouped_expr = try rp.c.arena.create(ast.Node.GroupedExpression);
grouped_expr.* = .{
.lparen = lparen,
.expr = block_node,
.rparen = rparen,
};
return maybeSuppressResult(rp, scope, result_used, &grouped_expr.base);
},
.Div => {
if (cIsSignedInteger(qt)) {

13
test/run_translated_c.zig
View File

@ -909,4 +909,17 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {
\\ return 1 != 1;
\\}
, "");
cases.add("Comma operator should create new scope; issue #7989",
\\#include <stdlib.h>
\\#include <stdio.h>
\\int main(void) {
\\ if (1 || (abort(), 1)) {}
\\ if (0 && (1, printf("do not print\n"))) {}
\\ int x = 0;
\\ x = (x = 3, 4, x + 1);
\\ if (x != 4) abort();
\\ return 0;
\\}
, "");
}

32
test/translate_c.zig
View File

@ -1723,11 +1723,17 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
\\}
, &[_][]const u8{
\\pub export fn foo() c_int {
\\ _ = @as(c_int, 2);
\\ _ = @as(c_int, 4);
\\ _ = @as(c_int, 2);
\\ _ = @as(c_int, 4);
\\ return @as(c_int, 6);
\\ _ = (blk: {
\\ _ = @as(c_int, 2);
\\ break :blk @as(c_int, 4);
\\ });
\\ return (blk: {
\\ _ = (blk_1: {
\\ _ = @as(c_int, 2);
\\ break :blk_1 @as(c_int, 4);
\\ });
\\ break :blk @as(c_int, 6);
\\ });
\\}
});
@ -1774,8 +1780,10 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
\\ while (true) {
\\ var a_1: c_int = 4;
\\ a_1 = 9;
\\ _ = @as(c_int, 6);
\\ return a_1;
\\ return (blk: {
\\ _ = @as(c_int, 6);
\\ break :blk a_1;
\\ });
\\ }
\\ while (true) {
\\ var a_1: c_int = 2;
@ -1805,9 +1813,13 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
\\ var b: c_int = 4;
\\ while ((i + @as(c_int, 2)) != 0) : (i = 2) {
\\ var a: c_int = 2;
\\ a = 6;
\\ _ = @as(c_int, 5);
\\ _ = @as(c_int, 7);
\\ _ = (blk: {
\\ _ = (blk_1: {
\\ a = 6;
\\ break :blk_1 @as(c_int, 5);
\\ });
\\ break :blk @as(c_int, 7);
\\ });
\\ }
\\ }
\\ var i: u8 = @bitCast(u8, @truncate(i8, @as(c_int, 2)));