fix Issue 14555 - ModuleInfo should weakly link against classes

src/backend/cgen.c

@@ -727,10 +727,6 @@ STATIC int outfixlist_dg(void *parameter, void *pkey, void *pvalue)
                 }
                 s->Sclass = SCextern;   /* make it external             */
                 objmod->external(s);
-                if (s->Sflags & SFLweak)
-                {
-                    objmod->wkext(s, NULL);
-                }
             }
 #if TARGET_OSX
             symbol *funcsymsave = funcsym_p;

src/backend/cgobj.c

@@ -1236,10 +1236,9 @@ STATIC void obj_defaultlib()
 
 /*******************************
  * Output a weak extern record.
- * s1 is the weak extern, s2 is its default resolution.
  */
 
-void Obj::wkext(Symbol *s1,Symbol *s2)
+static void wkext(Symbol *s1)
 {
     //printf("Obj::wkext(%s)\n", s1->Sident);
     if (I32)
@@ -1248,25 +1247,16 @@ void Obj::wkext(Symbol *s1,Symbol *s2)
         return;
     }
 
-    int x2;
-    if (s2)
-        x2 = s2->Sxtrnnum;
-    else
-    {
-        if (!obj.nullext)
-        {
-            obj.nullext = Obj::external_def("__nullext");
-        }
-        x2 = obj.nullext;
-    }
+    if (!obj.nullext)
+        obj.nullext = objmod->external_def("__nullext");
     outextdata();
 
     char buffer[2+2+2];
     buffer[0] = 0x80;
     buffer[1] = 0xA8;
     int i = 2;
     i += insidx(&buffer[2],s1->Sxtrnnum);
-    i += insidx(&buffer[i],x2);
+    i += insidx(&buffer[i],obj.nullext);
     objrecord(COMENT,buffer,i);
 }
 
@@ -2524,6 +2514,8 @@ int Obj::external(Symbol *s)
     e[len] = 0;                 // typidx = 0
     obj.extdatai += len + 1;
     s->Sxtrnnum = ++obj.extidx;
+    if (s->Sflags & SFLweak)
+        wkext(s);
     return obj.extidx;
 }
 

src/backend/cod1.c

@@ -2314,9 +2314,9 @@ code *callclib(elem *e,unsigned clib,regm_t *pretregs,regm_t keepmask)
         if (I16 &&                                   // bug in Optlink for weak references
             config.flags3 & CFG3wkfloat &&
             (info[clib].flags & (INFfloat | INFwkdone)) == INFfloat)
-        {   info[clib].flags |= INFwkdone;
-            makeitextern(rtlsym[RTLSYM_INTONLY]);
-            objmod->wkext(s,rtlsym[RTLSYM_INTONLY]);
+        {
+            info[clib].flags |= INFwkdone;
+            objmod->external(s,rtlsym[RTLSYM_INTONLY]);
         }
 #endif
     }

src/backend/elfobj.c

@@ -1492,15 +1492,6 @@ void Obj::user(const char *p)
     //dbg_printf("Obj::user(char *%s)\n",p);
 }
 
-/*******************************
- * Output a weak extern record.
- */
-
-void Obj::wkext(Symbol *s1,Symbol *s2)
-{
-    //dbg_printf("Obj::wkext(Symbol *%s,Symbol *s2)\n",s1->Sident,s2->Sident);
-}
-
 /*******************************
  * Output file name record.
  *
@@ -2285,9 +2276,8 @@ int Obj::external(Symbol *s)
     }
 
     s->Sxtrnnum = elf_addsym(namidx, size, size, symtype,
-        /*(s->ty() & mTYweak) ? STB_WEAK : */STB_GLOBAL, sectype);
+                             (s->Sflags & SFLweak) ? STB_WEAK : STB_GLOBAL, sectype);
     return s->Sxtrnnum;
-
 }
 
 /*******************************

src/backend/machobj.c

@@ -1235,6 +1235,8 @@ void Obj::term(const char *objfilename)
         sym.n_type = N_EXT | N_UNDF;
         sym.n_desc = tyfunc(s->ty()) ? REFERENCE_FLAG_UNDEFINED_LAZY
                                      : REFERENCE_FLAG_UNDEFINED_NON_LAZY;
+        if (s->Sflags & SFLweak)
+            sym.n_desc |= N_WEAK_REF;
         sym.n_sect = 0;
         if (I64)
             fobjbuf->write(&sym, sizeof(sym));
@@ -1484,15 +1486,6 @@ void Obj::user(const char *p)
     //dbg_printf("Obj::user(char *%s)\n",p);
 }
 
-/*******************************
- * Output a weak extern record.
- */
-
-void Obj::wkext(Symbol *s1,Symbol *s2)
-{
-    //dbg_printf("Obj::wkext(Symbol *%s,Symbol *s2)\n",s1->Sident,s2->Sident);
-}
-
 /*******************************
  * Output file name record.
  *

src/backend/mscoff.h

@@ -143,6 +143,7 @@ struct syment
 #define IMAGE_SYM_CLASS_LABEL           6
 #define IMAGE_SYM_CLASS_FUNCTION        101
 #define IMAGE_SYM_CLASS_FILE            103
+#define IMAGE_SYM_CLASS_WEAK_EXTERNAL   105
 
     unsigned char n_numaux;
 };

src/backend/mscoffobj.c

@@ -674,6 +674,13 @@ void build_syment_table(bool bigobj)
                 sym.n_value = s->Soffset;
                 break;
 
+            case SCcomdat:
+            case SCcomdef:
+                sym.n_sclass = IMAGE_SYM_CLASS_WEAK_EXTERNAL;
+                if (sym.n_scnum != IMAGE_SYM_UNDEFINED)
+                    sym.n_value = s->Soffset;
+                break;
+
             default:
                 sym.n_sclass = IMAGE_SYM_CLASS_EXTERNAL;
                 if (sym.n_scnum != IMAGE_SYM_UNDEFINED)
@@ -1219,15 +1226,6 @@ void MsCoffObj::user(const char *p)
     //dbg_printf("MsCoffObj::user(char *%s)\n",p);
 }
 
-/*******************************
- * Output a weak extern record.
- */
-
-void MsCoffObj::wkext(Symbol *s1,Symbol *s2)
-{
-    //dbg_printf("MsCoffObj::wkext(Symbol *%s,Symbol *s2)\n",s1->Sident,s2->Sident);
-}
-
 /*******************************
  * Output file name record.
  *

src/backend/obj.h

@@ -41,7 +41,6 @@ struct Obj
     VIRTUAL void exestr(const char *p);
     VIRTUAL void user(const char *p);
     VIRTUAL void compiler();
-    VIRTUAL void wkext(Symbol *,Symbol *);
     VIRTUAL void lzext(Symbol *,Symbol *);
     VIRTUAL void alias(const char *n1,const char *n2);
     VIRTUAL void theadr(const char *modname);
@@ -135,7 +134,6 @@ struct MsCoffObj : Obj
     VIRTUAL void exestr(const char *p);
     VIRTUAL void user(const char *p);
     VIRTUAL void compiler();
-    VIRTUAL void wkext(Symbol *,Symbol *);
 //    VIRTUAL void lzext(Symbol *,Symbol *);
     VIRTUAL void alias(const char *n1,const char *n2);
 //    VIRTUAL void theadr(const char *modname);
@@ -154,7 +152,6 @@ struct MsCoffObj : Obj
     VIRTUAL void export_symbol(Symbol *s, unsigned argsize);
     VIRTUAL void pubdef(int seg, Symbol *s, targ_size_t offset);
     VIRTUAL void pubdefsize(int seg, Symbol *s, targ_size_t offset, targ_size_t symsize);
-//    VIRTUAL int external(const char *);
     VIRTUAL int external_def(const char *);
     VIRTUAL int data_start(Symbol *sdata, targ_size_t datasize, int seg);
     VIRTUAL int external(Symbol *);

src/backend/rtlsym.h

@@ -148,7 +148,7 @@ SYMBOL_SCPP(AHSHIFT,   FLfunc,0,"_AHSHIFT",0,tstrace) \
 \
 SYMBOL_SCPP_TX86(HDIFFN, FLfunc,mBX|mCX|mSI|mDI|mBP|mES,"_aNahdiff", 0, 0) \
 SYMBOL_SCPP_TX86(HDIFFF, FLfunc,mBX|mCX|mSI|mDI|mBP|mES,"_aFahdiff", 0, 0) \
-SYMBOL_SCPP_TX86(INTONLY,FLfunc,mSI|mDI,"_intonly", 0, 0) \
+SYMBOL_SCPP_TX86(INTONLY,FLfunc,mSI|mDI,"_intonly", SFLweak, 0) \
 \
 SYMBOL_Z(EXCEPT_LIST, FLextern,0,"_except_list",0,tsint) \
 SYMBOL_Z(SETJMP3, FLfunc,FREGSAVED,"_setjmp3", 0, 0) \

src/toobj.c

@@ -173,12 +173,9 @@ void genModuleInfo(Module *m)
                 continue;
 
             Symbol *s = toSymbol(mod);
-
-            /* Weak references don't pull objects in from the library,
-             * they resolve to 0 if not pulled in by something else.
-             * Don't pull in a module just because it was imported.
-             */
-            s->Sflags |= SFLweak;
+            // Ideally we'd use weak linkage for ModuleInfos, but as
+            // they contain the list ctors/dtors, they need to be
+            // linked whenever something of the module is used.
             dtxoff(&dt, s, 0, TYnptr);
         }
     }
@@ -188,7 +185,10 @@ void genModuleInfo(Module *m)
         for (size_t i = 0; i < aclasses.dim; i++)
         {
             ClassDeclaration *cd = aclasses[i];
-            dtxoff(&dt, toSymbol(cd), 0, TYnptr);
+            Symbol *s = toSymbol(cd);
+            // use weak reference to reduce size of static binaries
+            s->Sflags |= SFLweak;
+            dtxoff(&dt, s, 0, TYnptr);
         }
     }
     if (flags & MIname)

test/runnable/extra-files/lib14555.d

@@ -0,0 +1,5 @@
+module lib14555;
+
+shared static this() {} // needs ModuleInfo
+class A {}
+class B {}

test/runnable/extra-files/test14555.d

@@ -0,0 +1,8 @@
+import lib14555;
+
+void main()
+{
+    auto dummyLinkA = new A();
+    assert(Object.factory("lib14555.A") !is null);
+    assert(Object.factory("lib14555.B") is null);
+}

test/runnable/test14555.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+src=runnable${SEP}extra-files
+dir=${RESULTS_DIR}${SEP}runnable
+output_file=${dir}/test14555.sh.out
+
+if [ $OS == "win32" -o  $OS == "win64" ]; then
+	LIBEXT=.lib
+else
+	LIBEXT=.a
+fi
+libname=${dir}${SEP}lib14555${LIBEXT}
+
+$DMD -m${MODEL} -I${src} -of${libname} -lib ${src}${SEP}lib14555.d || exit 1
+$DMD -m${MODEL} -I${src} -of${dir}${SEP}test14555${EXE} ${src}${SEP}test14555.d ${libname} || exit 1
+./${dir}${SEP}test14555${EXE} || exit 1
+
+rm ${dir}/{lib14555${LIBEXT},test14555${OBJ},test14555${EXE}}
+
+echo Success >${output_file}