Add test for padded inner macros

libs/preprocessor/tests/warnings/pw3_padded_arg_inner/source.hpp

@@ -0,0 +1,6 @@
+#define HELLO(var1, var2) INNER(Hello, var1##var2)
+#define GREET(var1, var2) INNER(Greetings, var1##var2)
+#define INNER(var1, var2) var1 var2
+
+value1 = HELLO(John,Smith); // Only inner
+value2 = GREET(John, Smith); // Both call and inner

libs/preprocessor/tests/warnings/pw3_padded_arg_inner/stderr.ansi

@@ -0,0 +1,27 @@
+warning[PW3]: padding a macro argument
+  ┌─ source.hpp:1:39
+  │
+1 │ #define HELLO(var1, var2) INNER(Hello, var1##var2)
+  │                                       ^ padding a macro argument
+  │
+  = note: padding a macro argument is likely unintended
+  = note: occured in: `INNER`
+
+warning[PW3]: padding a macro argument
+  ┌─ source.hpp:6:21
+  │
+6 │ value2 = GREET(John, Smith); // Both call and inner
+  │                     ^ padding a macro argument
+  │
+  = note: padding a macro argument is likely unintended
+  = note: occured in: `GREET`
+
+warning[PW3]: padding a macro argument
+  ┌─ source.hpp:2:43
+  │
+2 │ #define GREET(var1, var2) INNER(Greetings, var1##var2)
+  │                                           ^ padding a macro argument
+  │
+  = note: padding a macro argument is likely unintended
+  = note: occured in: `INNER`
+