From 7d7d4dc46c2063f60e36f6297eda47e0ec1b0cd6 Mon Sep 17 00:00:00 2001
From: Mumfrey <adam@eq2.co.uk>
Date: Sat, 6 Jul 2024 13:54:43 +0100
Subject: [PATCH] Properly handle empty args window and report name of the
 original method

---
 .../mixin/injection/invoke/ModifyArgInjector.java  |  7 ++++++-
 .../mixin/injection/invoke/ModifyArgsInjector.java |  2 +-
 .../asm/mixin/injection/struct/ArgOffsets.java     | 14 +++++++++-----
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgInjector.java b/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgInjector.java
index a6064f7a..9f50fa4a 100644
--- a/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgInjector.java
+++ b/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgInjector.java
@@ -115,6 +115,11 @@ protected void injectAtInvoke(Target target, InjectionNode node) {
         boolean nested = node.hasDecoration(ArgOffsets.KEY);
         Type[] originalArgs = offsets.apply(args);
         
+        if (originalArgs.length == 0) {
+            throw new InvalidInjectionException(this.info, "@ModifyArg injector " + this + " targets a method invocation "
+                    + ((MethodInsnNode)node.getOriginalTarget()).name + "()" + Type.getReturnType(methodNode.desc) + " with no arguments!");
+        }
+
         int argIndex = offsets.getArgIndex(this.findArgIndex(target, originalArgs));
         int baseIndex = offsets.getStartIndex();
         
@@ -125,7 +130,7 @@ protected void injectAtInvoke(Target target, InjectionNode node) {
             this.injectSingleArgHandler(target, extraLocals, args, argIndex, insns, nested);
         } else {
             if (!Arrays.equals(originalArgs, this.methodArgs)) {
-                throw new InvalidInjectionException(this.info, "@ModifyArg method " + this + " targets a method with an invalid signature "
+                throw new InvalidInjectionException(this.info, "@ModifyArg injector " + this + " targets a method with an invalid signature "
                         + Bytecode.getDescriptor(originalArgs) + ", expected " + Bytecode.getDescriptor(this.methodArgs));
             }
 
diff --git a/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgsInjector.java b/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgsInjector.java
index e5712dc0..53157f1e 100644
--- a/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgsInjector.java
+++ b/src/main/java/org/spongepowered/asm/mixin/injection/invoke/ModifyArgsInjector.java
@@ -88,7 +88,7 @@ protected void injectAtInvoke(Target target, InjectionNode node) {
         
         if (originalArgs.length == 0) {
             throw new InvalidInjectionException(this.info, "@ModifyArgs injector " + this + " targets a method invocation "
-                    + methodNode.name + targetMethodDesc + " with no arguments!");
+                    + ((MethodInsnNode)node.getOriginalTarget()).name + targetMethodDesc + " with no arguments!");
         }
         
         String clArgs = this.argsClassGenerator.getArgsClass(targetMethodDesc, this.info.getMixin().getMixin()).getName();
diff --git a/src/main/java/org/spongepowered/asm/mixin/injection/struct/ArgOffsets.java b/src/main/java/org/spongepowered/asm/mixin/injection/struct/ArgOffsets.java
index 4fcbcb49..2483cb02 100644
--- a/src/main/java/org/spongepowered/asm/mixin/injection/struct/ArgOffsets.java
+++ b/src/main/java/org/spongepowered/asm/mixin/injection/struct/ArgOffsets.java
@@ -95,9 +95,6 @@ public Type[] apply(Type[] args) {
      * @param length length
      */
     public ArgOffsets(int offset, int length) {
-        if (length < 1) {
-            throw new IllegalArgumentException("Invalid length " + length + " for ArgOffsets window");
-        }
         this.offset = offset;
         this.length = length;
     }
@@ -121,12 +118,19 @@ public void replace(ArgOffsets old) {
     }
     
     /**
-     * Get the size of this mapping collection
+     * Get the size of the offset window
      */
     public int getLength() {
         return this.length;
     }
     
+    /**
+     * Get whether this argument offset window is empty
+     */
+    public boolean isEmpty() {
+        return this.length == 0;
+    }
+    
     /**
      * Compute the argument index for the start of the window (offet 0)
      * 
@@ -142,7 +146,7 @@ public int getStartIndex() {
      * @return the offset index for the end of the window (inclusive)
      */
     public int getEndIndex() {
-        return this.getArgIndex(this.length - 1);
+        return this.isEmpty() ? this.getStartIndex() : this.getArgIndex(this.length - 1);
     }
     
     /**