[LLDB] Clarifying the documentation for variable formatting wrt to qu…

…alifiers and adding a test that demonstrates this

When looking up user specified formatters qualifiers are removed from types before matching,
I have added a clarifying example to the document and added an example to a relevant test to demonstrate this behavior.

Differential Revision: https://reviews.llvm.org/D99827

lldb/docs/use/variable.rst

@@ -131,6 +131,20 @@ which provides the desired output:
    (C) c = {0x03 0x00 0x00 0x00}
    (D) d = 4
 
+Note, that qualifiers such as const and volatile will be stripped when matching types for example:
+
+::
+
+   (lldb) frame var x y z
+   (int) x = 1
+   (const int) y = 2
+   (volatile int) z = 4
+   (lldb) type format add -f hex int
+   (lldb) frame var x y z
+   (int) x = 0x00000001
+   (const int) y = 0x00000002
+   (volatile int) z = 0x00000004
+
 Two additional options that you will want to look at are --skip-pointers (-p)
 and --skip-references (-r). These two options prevent LLDB from applying a
 format for type T to values of type T* and T& respectively.

lldb/test/API/functionalities/data-formatter/data-formatter-advanced/TestDataFormatterAdv.py

@@ -244,6 +244,12 @@ def cleanup():
         self.expect("frame variable a_simple_object", matching=True,
                     substrs=['x=0x00000003'])
 
+        self.expect_var_path("constInt", value='0x0000002a')
+
+        self.expect_var_path("volatileInt", value='0x0000002b')
+
+        self.expect_var_path("constVolatileInt", value='0x0000002c')
+
         # check that we can correctly cap the number of children shown
         self.runCmd("settings set target.max-children-count 5")
 

lldb/test/API/functionalities/data-formatter/data-formatter-advanced/main.cpp

@@ -128,6 +128,9 @@ int main (int argc, const char * argv[])
 {
 
     int iAmInt = 9;
+    const int constInt = 42;
+    volatile int volatileInt = 43;
+    const volatile int constVolatileInt = 44;
 
     i_am_cool cool_boy(1,0.5,3);
     i_am_cooler cooler_boy(1,2,0.1,0.2,'A','B');