no longer need extern "C" { } around epicsExport macros

documentation/RELEASE_NOTES.md

@@ -18,6 +18,11 @@ __This version of EPICS has not been released yet.__
 
 __Add new items below here__
 
+### epicsExport simplifications
+
+`epicsExportAddress()`, `epicsExportRegistrar()` and `epicsRegisterFunction()`
+no longer require to be wrapped in `extern "C" { }` in C++ code.
+
 ### New `dbServerStats()` API for iocStats
 
 A new routine provides the ability to request channel and client counts from

modules/database/test/std/rec/Makefile

@@ -221,6 +221,34 @@ testHarness_SRCS += linkFilterTest.c
 TESTFILES += ../linkFilterTest.db
 TESTS += linkFilterTest
 
+TARGETS += $(COMMON_DIR)/epicsExportTestIoc.dbd
+DBDDEPENDS_FILES += epicsExportTestIoc.dbd$(DEP)
+epicsExportTestIoc_DBD += base.dbd
+epicsExportTestIoc_DBD += epicsExportTest.dbd
+TESTFILES += $(COMMON_DIR)/epicsExportTestIoc.dbd ../epicsExportTest.db
+
+TESTLIBRARY += epicsExportTestLib
+epicsExportTestLib_SRCS += epicsExportTest.c
+epicsExportTestLib_LIBS += dbCore Com
+
+TESTPROD_HOST += epicsExportTest
+TESTS += epicsExportTest
+TARGETS += epicsExportTest$(OBJ)
+epicsExportTest_SRCS += epicsExportTestMain.c
+epicsExportTest_SRCS += epicsExportTestIoc_registerRecordDeviceDriver.cpp
+epicsExportTest_LIBS = epicsExportTestLib
+
+TESTLIBRARY += epicsExportTestxxLib
+epicsExportTestxxLib_SRCS += epicsExportTestxx.cpp
+epicsExportTestxxLib_LIBS += dbCore Com
+
+TESTPROD_HOST += epicsExportTestxx
+TESTS += epicsExportTestxx
+TARGETS += epicsExportTestxx$(OBJ)
+epicsExportTestxx_SRCS += epicsExportTestMain.c
+epicsExportTestxx_SRCS += epicsExportTestIoc_registerRecordDeviceDriver.cpp
+epicsExportTestxx_LIBS = epicsExportTestxxLib
+
 # These are compile-time tests, no need to link or run
 TARGETS += dbHeaderTest$(OBJ)
 TARGET_SRCS += dbHeaderTest.cpp

modules/database/test/std/rec/epicsExportTest.c

@@ -0,0 +1,146 @@
+/*************************************************************************\
+* Copyright (c) 2025 Dirk Zimoch
+* SPDX-License-Identifier: EPICS
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+/* Compile and link test for epicsExport.h
+* 
+* Test if macros eppicsExportAddr, epicsExportRegistrar and epicsRegisterFunction
+* expand to valid C and C++ code, in the latter case regardless if
+* wrapped with extern "C" {} or not.
+* Also test that those macros have the intended effect in both cases.
+*
+* This file is compiled directly as C
+* and included from epicsExportTestxx.cpp as C++
+*/
+
+#include <epicsUnitTest.h>
+#include <dbUnitTest.h>
+#include <testMain.h>
+#include <dbAccess.h>
+#include <longinRecord.h>
+#include <aSubRecord.h>
+#include <iocsh.h>
+#include <registryFunction.h>
+#include <epicsExport.h>
+
+int i1, i2;
+volatile int v1=10, v2=20;
+const int c1=100, c2=200;
+
+static long myReadLongin(struct dbCommon* prec)
+{
+    struct longinRecord* pli =
+#ifdef __cplusplus
+        reinterpret_cast<struct longinRecord*>(prec);
+#else
+        (struct longinRecord*)prec;
+#endif
+    pli->val=5;
+    return 0;
+}
+
+/* Also test cast from user-specific const mydset to dset */
+const struct mydset {
+    long number;
+    long (*report)(int);
+    long (*init)(int);
+    long (*init_record)(struct dbCommon*);
+    long (*get_ioint_info)(int, struct dbCommon*, IOSCANPVT*);
+    long (*process)(struct dbCommon*);
+    long (*something_else)(struct dbCommon*);
+} dset1 = {
+    6,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    myReadLongin,
+    NULL
+}, dset2 = {
+    6,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    myReadLongin,
+    NULL
+};
+
+static void registrar1() {
+    i1++;
+    testPass("registrar1 executed");
+}
+
+static void registrar2() {
+    i2++;
+    testPass("registrar2 executed");
+}
+
+/* Also test cast from int(*)() to REGISTRAR */
+static int registrar3() {
+    i1++;
+    testPass("registrar3 executed");
+    return 0;
+}
+
+static int registrar4() {
+    i2++;
+    testPass("registrar4 executed");
+    return 0;
+}
+
+/* Test both, native (potentially C++) and extern "C" functions */
+static long aSubInit1(aSubRecord* prec) {
+    *(epicsInt32*)prec->a = 1;
+    return 0;
+}
+
+static long aSubProc1(aSubRecord* prec) {
+    *(epicsInt32*)prec->b = 2;
+    return 0;
+}
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+static long aSubInit2(aSubRecord* prec) {
+    *(epicsInt32*)prec->a = 3;
+    return 0;
+}
+static long aSubProc2(aSubRecord* prec) {
+    *(epicsInt32*)prec->b = 4;
+    return 0;
+}
+#ifdef __cplusplus
+}
+#endif
+
+/* Test without wrapping */
+epicsExportAddress(int, i1);
+epicsExportAddress(int, v1);
+epicsExportAddress(int, c1);
+epicsExportAddress(dset, dset1);
+epicsExportRegistrar(registrar1);
+epicsExportRegistrar(registrar3);
+epicsRegisterFunction(aSubInit1);
+epicsRegisterFunction(aSubProc1);
+
+/* In C++ test wrapped in extern "C" {} */
+#ifdef __cplusplus
+extern "C" {
+#endif
+epicsExportAddress(int, i2);
+epicsExportAddress(int, v2);
+epicsExportAddress(int, c2);
+epicsExportAddress(dset, dset2);
+epicsExportRegistrar(registrar2);
+epicsExportRegistrar(registrar4);
+epicsRegisterFunction(aSubInit2);
+epicsRegisterFunction(aSubProc2);
+
+#ifdef __cplusplus
+}
+#endif

modules/database/test/std/rec/epicsExportTest.db

@@ -0,0 +1,24 @@
+record(longin, "li1") {
+  field(DTYP, "dset1")
+  field(VAL, "-1")
+}
+record(longin, "li2") {
+  field(DTYP, "dset2")
+  field(VAL, "-2")
+}
+record(aSub, "asub1") {
+  field(FTA, "LONG")
+  field(FTB, "LONG")
+  field(INPA, "-1")
+  field(INPB, "-2")
+  field(INAM, "aSubInit1")
+  field(SNAM, "aSubProc1")
+}
+record(aSub, "asub2") {
+  field(FTA, "LONG")
+  field(FTB, "LONG")
+  field(INPA, "-3")
+  field(INPB, "-4")
+  field(INAM, "aSubInit2")
+  field(SNAM, "aSubProc2")
+}

modules/database/test/std/rec/epicsExportTest.dbd

@@ -0,0 +1,16 @@
+variable(i1,int)
+variable(i2,int)
+variable(v1,int)
+variable(v2,int)
+variable(c1,int)
+variable(c2,int)
+device(longin, CONSTANT, dset1, "dset1")
+device(longin, CONSTANT, dset2, "dset2")
+registrar(registrar1)
+registrar(registrar2)
+registrar(registrar3)
+registrar(registrar4)
+function(aSubInit1)
+function(aSubProc1)
+function(aSubInit2)
+function(aSubProc2)

modules/database/test/std/rec/epicsExportTestMain.c

@@ -0,0 +1,95 @@
+/*************************************************************************\
+* Copyright (c) 2025 Dirk Zimoch
+* SPDX-License-Identifier: EPICS
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+/* Compile and link test for epicsExport.h
+* 
+*/
+
+#include <epicsUnitTest.h>
+#include <dbUnitTest.h>
+#include <testMain.h>
+#include <dbAccess.h>
+#include <iocsh.h>
+#include <epicsExport.h>
+
+#ifdef __cplusplus
+extern "C"
+#endif
+int epicsExportTestIoc_registerRecordDeviceDriver(struct dbBase *);
+
+static int* testVarEquals(const char* name, int expected)
+{
+    const iocshVarDef *var;
+    int *p;
+
+    var = iocshFindVariable(name);
+    if (!var) {
+        testFail("Cannot access variable %s", name);
+        return NULL;
+    }
+    if (var->type != iocshArgInt) {
+        testFail("Variable %s has wrong type", name);
+        return NULL;
+    }
+    p = (int*)(var->pval);
+    testOk(*p == expected, "Variable %s == %d", name, expected);
+    return p;
+}
+
+MAIN(epicsExportTest)
+{
+    int *p1, *p2;
+
+    testPlan(31);
+    testdbPrepare();
+    testdbReadDatabase("epicsExportTestIoc.dbd", 0, 0);
+    testOk(epicsExportTestIoc_registerRecordDeviceDriver(pdbbase)==0, "registerRecordDeviceDriver");
+
+    testDiag("Testing if dsets and functions are found");
+    testdbReadDatabase("epicsExportTest.db", 0, 0);
+    testIocInitOk();
+
+    testDiag("Testing if dsets work correctly");
+    testdbGetFieldEqual("li1", DBF_LONG, -1);
+    testdbGetFieldEqual("li2", DBF_LONG, -2);
+    testdbPutFieldOk("li1.PROC", DBF_LONG, 1);
+    testdbPutFieldOk("li2.PROC", DBF_LONG, 1);
+    testdbGetFieldEqual("li1", DBF_LONG, 5);
+    testdbGetFieldEqual("li2", DBF_LONG, 5);
+
+    testDiag("Testing if functions work correctly");
+    testdbGetFieldEqual("asub1.A", DBF_LONG, 1);
+    testdbGetFieldEqual("asub1.B", DBF_LONG, -2);
+    testdbGetFieldEqual("asub2.A", DBF_LONG, 3);
+    testdbGetFieldEqual("asub2.B", DBF_LONG, -4);
+    testdbPutFieldOk("asub1.PROC", DBF_LONG, 1);
+    testdbPutFieldOk("asub2.PROC", DBF_LONG, 1);
+    testdbGetFieldEqual("asub1.A", DBF_LONG, 1);
+    testdbGetFieldEqual("asub1.B", DBF_LONG, 2);
+    testdbGetFieldEqual("asub2.A", DBF_LONG, 3);
+    testdbGetFieldEqual("asub2.B", DBF_LONG, 4);
+
+    testDiag("Testing if variable access works");
+    p1 = testVarEquals("i1", 2);
+    p2 = testVarEquals("i2", 2);
+    testVarEquals("v1", 10);
+    testVarEquals("v2", 20);
+    testVarEquals("c1", 100);
+    testVarEquals("c2", 200);
+
+    if (p1 && p2) {
+        testDiag("Testing if variables are accessible from iocsh");
+        testOk(iocshCmd("var i1,4") == 0, "Setting i1 = 4 in iocsh");
+        testOk(iocshCmd("var i2,5") == 0, "Setting i2 = 5 in iocsh");
+        testOk(*p1==4, "Variable i1 == 4");
+        testOk(*p2==5, "Variable i2 == 5");
+    }
+
+    testIocShutdownOk();
+    testdbCleanup();
+    return testDone();
+}

modules/database/test/std/rec/epicsExportTestxx.cpp

@@ -0,0 +1,2 @@
+// just compile as c++
+#include "epicsExportTest.c"

modules/libcom/src/misc/epicsExport.h

@@ -41,6 +41,10 @@ extern "C" {
 
 typedef void (*REGISTRAR)(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #define EPICS_EXPORT_POBJ(typ, obj) pvar_ ## typ ## _ ## obj
 #define EPICS_EXPORT_PFUNC(fun) EPICS_EXPORT_POBJ(func, fun)
 
@@ -75,12 +79,16 @@ typedef void (*REGISTRAR)(void);
  *
  * \param typ Object's data type.
  * \param obj Object's name.
- *
- * \note C++ code needs to wrap with @code extern "C" { } @endcode
  */
+#ifdef __cplusplus
+#define epicsExportAddress(typ, obj) \
+    extern "C" { epicsShareExtern typ *EPICS_EXPORT_POBJ(typ,obj); } \
+    epicsShareDef typ *EPICS_EXPORT_POBJ(typ, obj) = (typ *) (char *) &obj
+#else
 #define epicsExportAddress(typ, obj) \
     epicsShareExtern typ *EPICS_EXPORT_POBJ(typ,obj); \
     epicsShareDef typ *EPICS_EXPORT_POBJ(typ, obj) = (typ *) (char *) &obj
+#endif
 
 /** \brief Declare a registrar function for exporting.
  *
@@ -94,11 +102,15 @@ typedef void (*REGISTRAR)(void);
  \endcode
  *
  * \param fun Registrar function's name.
- *
- * \note C++ code needs to wrap with @code extern "C" { } @endcode
  */
+#ifdef __cplusplus
+#define epicsExportRegistrar(fun) \
+    extern "C" { extern epicsShareFunc REGISTRAR EPICS_EXPORT_PFUNC(fun); } \
+    REGISTRAR EPICS_EXPORT_PFUNC(fun) = reinterpret_cast<REGISTRAR>(&fun)
+#else
 #define epicsExportRegistrar(fun) \
     epicsShareFunc REGISTRAR EPICS_EXPORT_PFUNC(fun) = (REGISTRAR) &fun
+#endif
 
 /** \brief Declare and register a function for exporting.
  *
@@ -111,18 +123,21 @@ typedef void (*REGISTRAR)(void);
  \endcode
 *
  * \param fun Function's name
- *
- * \note C++ code needs to wrap with @code extern "C" { } @endcode
  */
+#ifdef __cplusplus
+#define epicsRegisterFunction(fun) \
+    static void register_func_ ## fun(void) \
+    { \
+        registryFunctionAdd(#fun, reinterpret_cast<REGISTRYFUNCTION>(fun)); \
+    } \
+    epicsExportRegistrar(register_func_ ## fun)
+#else
 #define epicsRegisterFunction(fun) \
     static void register_func_ ## fun(void) \
     { \
         registryFunctionAdd(#fun, (REGISTRYFUNCTION) fun); \
     } \
     epicsExportRegistrar(register_func_ ## fun)
-
-#ifdef __cplusplus
-}
 #endif
 
 #endif /* INC_epicsExport_H */