Implement default argument promotions (for old-style function calls and variable...

Implement default argument promotions (for old-style function calls and variable argument lists).

[dylan:~/llvm/tools/clang] admin% cat x.c

int printf(const char *, ...);

int oldschool();

void foo() {
  float f;
  short i;
  printf("foo %f", 1.0f);

  oldschool(f,i);
}

[dylan:~/llvm/tools/clang] admin% ../../Debug/bin/clang x.c -parse-ast-dump

int printf(char const *, ...);

int oldschool();

void foo()
(CompoundStmt 0x3105f00
  (DeclStmt 0x3105ba0
    0x3105ce0 "float f")
  (DeclStmt 0x3105c90
    0x3105d10 "short i")
  (CallExpr 0x3105df0 'int'
    (ImplicitCastExpr 0x3105dc0 'int (*)(char const *, ...)'
      (DeclRefExpr 0x3105c20 'int (char const *, ...)' Decl='printf' 0x3105bd0))
    (ImplicitCastExpr 0x3105dd0 'char const *'
      (StringLiteral 0x3105d60 'char *' "foo %f"))
    (ImplicitCastExpr 0x3105de0 'double'
      (FloatingLiteral 0x3105d80 'float' 1.000000)))
  (CallExpr 0x3105ed0 'int'
    (ImplicitCastExpr 0x3105ea0 'int (*)()'
      (DeclRefExpr 0x3105e20 'int ()' Decl='oldschool' 0x3105c40))
    (ImplicitCastExpr 0x3105eb0 'double'
      (DeclRefExpr 0x3105e40 'float' Decl='f' 0x3105ce0))
    (ImplicitCastExpr 0x3105ec0 'int'
      (DeclRefExpr 0x3105e60 'short' Decl='i' 0x3105d10))))

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@41558 91177308-0d34-0410-b5e6-96231b3b80d8