fix Issue 22960 - importC: K&R-style functions assume variadic calling convention (#15107)

compiler/src/dmd/astbase.d

@@ -3951,7 +3951,7 @@ struct ASTBase
         extern (D) this(ParameterList pl, Type treturn, LINK linkage, StorageClass stc = 0)
         {
             super(Tfunction, treturn);
-            assert(VarArg.none <= pl.varargs && pl.varargs <= VarArg.typesafe);
+            assert(VarArg.none <= pl.varargs && pl.varargs <= VarArg.max);
             this.parameterList = pl;
             this.linkage = linkage;
 

compiler/src/dmd/astenums.d

@@ -327,6 +327,7 @@ enum VarArg : ubyte
     variadic = 1,  /// (T t, ...)  can be C-style (core.stdc.stdarg) or D-style (core.vararg)
     typesafe = 2,  /// (T t ...) typesafe https://dlang.org/spec/function.html#typesafe_variadic_functions
                    ///   or https://dlang.org/spec/function.html#typesafe_variadic_functions
+    KRvariadic = 3, /// K+R C style variadics (no function prototype)
 }
 
 /*************************

compiler/src/dmd/cparse.d

@@ -2081,8 +2081,7 @@ final class CParser(AST) : Parser!AST
             auto pl = ft.parameterList;
             if (pl.varargs != AST.VarArg.none && pl.length)
                 error("function identifier-list cannot end with `...`");
-            ft.parameterList.varargs = AST.VarArg.variadic;     // but C11 allows extra arguments
+            ft.parameterList.varargs = AST.VarArg.KRvariadic;   // but C11 allows extra arguments
-            importBuiltins = true;                              // will need __va_list_tag
             auto plLength = pl.length;
             if (symbols.length != plLength)
                 error(token.loc, "%d identifiers does not match %d declarations", cast(int)plLength, cast(int)symbols.length);
@@ -3046,8 +3045,7 @@ final class CParser(AST) : Parser!AST
         if (token.value == TOK.rightParenthesis)        // func()
         {
             nextToken();
-            importBuiltins = true;                              // will need __va_list_tag
+            return AST.ParameterList(parameters, AST.VarArg.KRvariadic, varargsStc);
-            return AST.ParameterList(parameters, AST.VarArg.variadic, varargsStc);
         }
 
         /* Create function prototype scope

compiler/src/dmd/expressionsem.d

@@ -2265,7 +2265,8 @@ private bool functionParameters(const ref Loc loc, Scope* sc,
                 default:
                     break;
                 }
-                if (tf.parameterList.varargs == VarArg.variadic)
+                if (tf.parameterList.varargs == VarArg.variadic ||
+                    tf.parameterList.varargs == VarArg.KRvariadic)
                 {
                     const(char)* p = tf.linkage == LINK.c ? "extern(C)" : "extern(C++)";
                     if (arg.type.ty == Tarray)

compiler/src/dmd/frontend.h

@@ -2405,6 +2405,7 @@ enum class VarArg : uint8_t
     none = 0u,
     variadic = 1u,
     typesafe = 2u,
+    KRvariadic = 3u,
 };
 
 struct ParameterList final
@@ -8873,7 +8874,9 @@ struct Id final
     static Identifier* naked;
     static Identifier* thread;
     static Identifier* vector_size;
+    static Identifier* noinline;
     static Identifier* noreturn;
+    static Identifier* _deprecated;
     static Identifier* _align;
     static Identifier* aligned;
     static Identifier* builtins;

compiler/src/dmd/glue.d

@@ -1520,7 +1520,8 @@ tym_t totym(Type tx)
                 case LINK.windows:
                     if (target.is64bit)
                         goto case LINK.c;
-                    t = (tf.parameterList.varargs == VarArg.variadic) ? TYnfunc : TYnsfunc;
+                    t = (tf.parameterList.varargs == VarArg.variadic ||
+                         tf.parameterList.varargs == VarArg.KRvariadic) ? TYnfunc : TYnsfunc;
                     break;
 
                 case LINK.c:

compiler/src/dmd/hdrgen.d

@@ -3229,6 +3229,7 @@ private void parametersToBuffer(ParameterList pl, OutBuffer* buf, HdrGenState* h
     final switch (pl.varargs)
     {
         case VarArg.none:
+        case VarArg.KRvariadic:
             break;
 
         case VarArg.variadic:

compiler/src/dmd/inline.d

@@ -1722,7 +1722,8 @@ private bool canInline(FuncDeclaration fd, bool hasthis, bool hdrscan, bool stat
         TypeFunction tf = fd.type.isTypeFunction();
 
         // no variadic parameter lists
-        if (tf.parameterList.varargs == VarArg.variadic)
+        if (tf.parameterList.varargs == VarArg.variadic ||
+            tf.parameterList.varargs == VarArg.KRvariadic)
             goto Lno;
 
         /* No lazy parameters when inlining by statement, as the inliner tries to

compiler/src/dmd/mtype.d

@@ -4267,7 +4267,7 @@ extern (C++) final class TypeFunction : TypeNext
         super(Tfunction, treturn);
         //if (!treturn) *(char*)0=0;
         //    assert(treturn);
-        assert(VarArg.none <= pl.varargs && pl.varargs <= VarArg.typesafe);
+        assert(VarArg.none <= pl.varargs && pl.varargs <= VarArg.max);
         this.parameterList = pl;
         this.linkage = linkage;
 

compiler/src/dmd/traits.d

@@ -1316,6 +1316,7 @@ Expression semanticTraits(TraitsExp e, Scope* sc)
          *  "argptr"    extern(D) void dstyle(...), use `__argptr` and `__arguments`
          *  "stdarg"    extern(C) void cstyle(int, ...), use core.stdc.stdarg
          *  "typesafe"  void typesafe(T[] ...)
+         *  "KR"        old K+R style
          */
         // get symbol linkage as a string
         if (dim != 1)
@@ -1350,6 +1351,7 @@ Expression semanticTraits(TraitsExp e, Scope* sc)
             case VarArg.variadic: style = (link == LINK.d)
                                              ? "argptr"
                                              : "stdarg";    break;
+            case VarArg.KRvariadic: style = "KR";           break;
             case VarArg.typesafe: style = "typesafe";       break;
         }
         auto se = new StringExp(e.loc, style);

compiler/test/compilable/cvariadic.i

@@ -0,0 +1,11 @@
+int abc() { return 1; }
+int def(const char *p, ...) { return 2; }
+int ghi(const char *p, int i) { return 3; }
+
+int main()
+{
+    abc("hello world %d\n", 1);
+    def("hello world %d\n", 2);
+    ghi("hello world %d\n", 3);
+    return 0;
+}