improve cname handling

Author: timotheecour

compiler/ast.nim

@@ -857,8 +857,9 @@ type
     loc*: TLoc
     annex*: PLib              # additional fields (seldom used, so we use a
                               # reference to another object to save space)
-    cname*: string            # resolved C declaration name in importc decl, eg:
-                              # {.importc: "foo".} => cname = foo
+    when hasFFI:
+      cname*: string          # resolved C declaration name in importc decl, eg:
+                              # proc fun() {.importc: "$1aux".} => cname = funaux
     constraint*: PNode        # additional constraints like 'lit|result'; also
                               # misused for the codegenDecl pragma in the hope
                               # it won't cause problems

compiler/cgen.nim

@@ -701,10 +701,6 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
 proc mangleDynLibProc(sym: PSym): Rope =
   # we have to build this as a single rope in order not to trip the
   # optimization in genInfixCall, see test tests/cpp/t8241.nim
-  if sym.loc.r != nil:
-    # `return rope($sym.loc.r)` would cause on windows a SIGSEGV in
-    # stdlib_winleanDatInit000 () at generated_not_to_break_here
-    if sym.cname.len == 0: sym.cname = $sym.loc.r
   if sfCompilerProc in sym.flags:
     # NOTE: sym.loc.r is the external name!
     result = rope(sym.name.s)

compiler/evalffi.nim

@@ -47,8 +47,7 @@ const
   nkPtrLit = nkIntLit # hopefully we can get rid of this hack soon
 
 proc importcSymbol*(conf: ConfigRef, sym: PSym): PNode =
-  var name = $sym.cname
-  if name.len == 0: name = $sym.loc.r
+  var name = sym.cname # $sym.loc.r would point to internal name
   # the AST does not support untyped pointers directly, so we use an nkIntLit
   # that contains the address instead:
   result = newNodeIT(nkPtrLit, sym.info, sym.typ)

compiler/pragmas.nim

@@ -129,6 +129,8 @@ proc setExternName(c: PContext; s: PSym, extname: string, info: TLineInfo) =
       s.loc.r = rope(extname % s.name.s)
     except ValueError:
       localError(c.config, info, "invalid extern name: '" & extname & "'. (Forgot to escape '$'?)")
+  when hasFFI:
+    s.cname = $s.loc.r
   if c.config.cmd == cmdPretty and '$' notin extname:
     # note that '{.importc.}' is transformed into '{.importc: "$1".}'
     s.loc.flags.incl(lfFullExternalName)