Add _cstring literal suffix and document

docs/index.html

@@ -176,7 +176,7 @@ <h2>What is Nelua?</h2>
         <p>
         Nelua takes advantage of ahead of time compilation
         using powerful optimized C compilers such as GCC or Clang thus generating very
-        efficient native code, it doesn't use a interpreter at runtime.
+        efficient native code, it doesn't use an interpreter at runtime.
         </p>
       </div>
       <div class="col">

docs/pages/overview.md

@@ -453,8 +453,9 @@ Number literals are defined similar as in Lua:
 local a = 1234 -- variable of type 'integer'
 local b = 0xff -- variable of type 'integer'
 local c = 3.14159 -- variable of type 'number'
-local d: integer
-print(a,b,c,d) -- outputs: 1234 255 3.141590 0
+local d = 'A'_uint8 -- variable of type 'uint8' set from an ASCII character
+local e: integer
+print(a,b,c,d,e) -- outputs: 1234 255 3.141590 65 0
 ```
 
 The `integer` is the default type for integral literals without suffix.
@@ -2315,6 +2316,7 @@ For importing C functions, additional compatibility primitive types are provided
 | `culonglong`      | `unsigned long long` | `_culonglong`    |
 | `csize`           | `size_t`             | `_csize`         |
 | `clongdouble`     | `long double`        | `_clongdouble`   |
+| `cstring`         | `char*`              | `_cstring`       |
 {: .table.table-bordered.table-striped.table-sm}
 
 Use this types for **importing C functions only**, for doing usual

nelua/analyzer.lua

@@ -73,11 +73,15 @@ function visitors.String(_, node)
     if not type then
       node:raisef("literal suffix '%s' is undefined for strings", literal)
     end
-    if #value ~= 1 then
-      node:raisef("literal suffix '%s' expects a string of length 1")
+    if type.is_arithmetic then
+      if #value ~= 1 then
+        node:raisef("literal suffix '%s' expects a string of length 1")
+      end
+      attr.type = type
+      value = bn.new(string.byte(value))
+    elseif type.is_cstring then
+      attr.type = primtypes.cstring
     end
-    attr.type = type
-    value = bn.new(string.byte(value))
   else
     if node.desiredtype and node.desiredtype.is_cstring then
       attr.type = primtypes.cstring

nelua/typedefs.lua

@@ -149,6 +149,7 @@ typedefs.string_literals_types = {
   _cchar       = primtypes.cchar,
   _cuchar      = primtypes.cuchar,
   _cschar      = primtypes.cschar,
+  _cstring     = primtypes.cstring,
 }
 
 -- Ordered list of signed types for performing type promotion.

spec/05-cgenerator_spec.lua

@@ -58,6 +58,7 @@ it("number literals", function()
   assert.generate_c("local a = ' '_cchar", "char a = ' ';")
   assert.generate_c("local a = ' '_cschar", "signed char a = 32;")
   assert.generate_c("local a = ' '_cuchar", "unsigned char a = 32U;")
+  assert.generate_c("local a = 'str'_cstring", 'char* a = __strlit')
 end)
 
 it("type cast", function()