🐞 Fix LibString.packTwo() (#1510)

* 🐞 Fix packTwo

* f fmt

* T

* T

* fix typo

Author: atarpara

foundry.toml

@@ -15,6 +15,8 @@ fs_permissions = [{ access = "read", path = "./test/data"}]
 remappings = [
   "forge-std=test/utils/forge-std/"
 ]
+# remove memory-safe-assembly warning from compiler
+ignored_error_codes = [2424,8429,4591]
 
 [profile.pre_global_structs]
 skip = ["*/g/*", "*/*7702*", "*/*BlockHashLib*", "*/*Transient*", "*/ext/ithaca/*", "*/ext/zksync/*"]
@@ -46,6 +48,9 @@ remappings = [
   "forge-std=test/utils/forge-std/"
 ]
 
+[lint]
+lint_on_build = false
+
 [fmt]
 line_length = 100 # While we allow up to 120, we lint at 100 for readability.
 ignore = ["src/accounts/EIP7702Proxy.sol"]

src/utils/LibString.sol

@@ -926,7 +926,7 @@ library LibString {
             result := mul(
                 or( // Load the length and the bytes of `a` and `b`.
                     shl(shl(3, sub(0x1f, aLen)), mload(add(a, aLen))),
-                    mload(sub(add(b, 0x1e), aLen))
+                    shr(shl(3, add(aLen, 1)), mload(add(b, 0x1f)))
                 ),
                 // `totalLen != 0 && totalLen < 31`. Abuses underflow.
                 // Assumes that the lengths are valid and within the block gas limit.

src/utils/g/LibString.sol

@@ -930,7 +930,7 @@ library LibString {
             result := mul(
                 or( // Load the length and the bytes of `a` and `b`.
                     shl(shl(3, sub(0x1f, aLen)), mload(add(a, aLen))),
-                    mload(sub(add(b, 0x1e), aLen))
+                    shr(shl(3, add(aLen, 1)), mload(add(b, 0x1f)))
                 ),
                 // `totalLen != 0 && totalLen < 31`. Abuses underflow.
                 // Assumes that the lengths are valid and within the block gas limit.

test/LibString.t.sol

@@ -1456,6 +1456,14 @@ contract LibStringTest is SoladyTest {
             testStringPackAndUnpackTwo("abcdefghijklmnopqrstuvwxyzABCD", "");
             testStringPackAndUnpackTwo("The strongest community I've ever seen", "NGL");
             testStringPackAndUnpackTwo("", "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
+            testStringPackAndUnpackTwo(
+                "01234567890123456789012345678901_search_search_search_search_search_search_23456789012345678901234567890123456789_search_search_search_search_search_search",
+                ""
+            );
+            testStringPackAndUnpackTwoDifferential(
+                "01234567890123456789012345678901_search_search_search_search_search_search_23456789012345678901234567890123456789_search_search_search_search_search_search",
+                ""
+            );
         }
     }