ICU-21833 remove redundant void parameter lists

See unicode-org#2351

Author: markusicu

docs/userguide/locale/resources.md

@@ -335,7 +335,7 @@ accessed using indexes and by iteration.
 In order to be able to distinguish between resources, one needs to know the type
 of the resource at hand. To find this out, use the
 `UResType ures_getType(UResourceBundle* resourceBundle)` API, or the C++ analog
-`UResType getType(void)`. The `UResType` is an enumeration defined in the
+`UResType getType()`. The `UResType` is an enumeration defined in the
 [unicode/ures.h](https://github.com/unicode-org/icu/blob/main/icu4c/source/common/unicode/ures.h)
 header file.
 
@@ -443,8 +443,8 @@ ures_close(currentZone);
 ...
 ```
 
-C++ provides analogous APIs: `ResourceBundle getNext(UErrorCode& status)`, `void resetIterator(void)`
- and `UBool hasNext(void)`.
+C++ provides analogous APIs: `ResourceBundle getNext(UErrorCode& status)`, `void resetIterator()`
+ and `UBool hasNext()`.
 
 #### Accessing Data in the Simple Resources
 
@@ -540,22 +540,22 @@ following tables.
 | Language | API                                                     |
 | -------- | ------------------------------------------------------- |
 | C        | `int32_t ures_getSize(UResourceBundle* resourceBundle)` |
-| C++      | `int32_t getSize(void) const`                           |
+| C++      | `int32_t getSize() const`                               |
 
 Gets the number of items in a resource. Simple resources always return size 1.
 
 | Language | API                                                      |
 | -------- | -------------------------------------------------------- |
 | C        | `UResType ures_getType(UResourceBundle* resourceBundle)` |
-| C++      | `UResType getType(void)`                                 |
+| C++      | `UResType getType()`                                     |
 
 Gets the type of the resource. For a list of resource types, see:
 [unicode/ures.h](https://github.com/unicode-org/icu/blob/main/icu4c/source/common/unicode/ures.h)
 
 | Language | API                                              |
 | -------- | ------------------------------------------------ |
 | C        | `const char* ures_getKey(UResourceBundle* resB)` |
-| C++      | `const char* getKey(void)`                       |
+| C++      | `const char* getKey()`                           |
 
 Gets the key of a named resource or `NULL` if this resource is a member of an
 array.
@@ -570,7 +570,7 @@ Fills out the version structure for this resource.
 | Language | API                                                                                     |
 | -------- | --------------------------------------------------------------------------------------- |
 | C        | `const char* ures_getLocale(const UResourceBundle* resourceBundle, UErrorCode* status)` |
-| C++      | `const Locale& getLocale(void) const`                                                   |
+| C++      | `const Locale& getLocale() const`                                                       |
 
 Returns the locale this resource is from. This API is going to change, so stay
 tuned.

icu4c/source/common/brkiter.cpp

@@ -288,7 +288,7 @@ static icu::ICULocaleService* gService = nullptr;
  * Release all static memory held by breakiterator.
  */
 U_CDECL_BEGIN
-static UBool U_CALLCONV breakiterator_cleanup(void) {
+static UBool U_CALLCONV breakiterator_cleanup() {
 #if !UCONFIG_NO_SERVICE
     if (gService) {
         delete gService;
@@ -302,13 +302,13 @@ U_CDECL_END
 U_NAMESPACE_BEGIN
 
 static void U_CALLCONV 
-initService(void) {
+initService() {
     gService = new ICUBreakIteratorService();
     ucln_common_registerCleanup(UCLN_COMMON_BREAKITERATOR, breakiterator_cleanup);
 }
 
 static ICULocaleService*
-getService(void)
+getService()
 {
     umtx_initOnce(gInitOnceBrkiter, &initService);
     return gService;
@@ -318,7 +318,7 @@ getService(void)
 // -------------------------------------
 
 static inline UBool
-hasService(void)
+hasService()
 {
     return !gInitOnceBrkiter.isReset() && getService() != nullptr;
 }
@@ -353,7 +353,7 @@ BreakIterator::unregister(URegistryKey key, UErrorCode& status)
 // -------------------------------------
 
 StringEnumeration* U_EXPORT2
-BreakIterator::getAvailableLocales(void)
+BreakIterator::getAvailableLocales()
 {
     ICULocaleService *service = getService();
     if (service == nullptr) {

icu4c/source/common/chariter.cpp

@@ -86,13 +86,13 @@ CharacterIterator::operator=(const CharacterIterator &that) {
 // implementing first[32]PostInc() directly in a subclass should be faster
 // but these implementations make subclassing a little easier
 char16_t
-CharacterIterator::firstPostInc(void) {
+CharacterIterator::firstPostInc() {
     setToStart();
     return nextPostInc();
 }
 
 UChar32
-CharacterIterator::first32PostInc(void) {
+CharacterIterator::first32PostInc() {
     setToStart();
     return next32PostInc();
 }

icu4c/source/common/cmemory.cpp

@@ -129,7 +129,7 @@ u_setMemoryFunctions(const void *context, UMemAllocFn *a, UMemReallocFn *r, UMem
 }
 
 
-U_CFUNC UBool cmemory_cleanup(void) {
+U_CFUNC UBool cmemory_cleanup() {
     pContext   = nullptr;
     pAlloc     = nullptr;
     pRealloc   = nullptr;

icu4c/source/common/filteredbrk.cpp

@@ -191,7 +191,7 @@ class SimpleFilteredSentenceBreakIterator : public BreakIterator {
     return clone();
   }
   virtual SimpleFilteredSentenceBreakIterator* clone() const override { return new SimpleFilteredSentenceBreakIterator(*this); }
-  virtual UClassID getDynamicClassID(void) const override { return nullptr; }
+  virtual UClassID getDynamicClassID() const override { return nullptr; }
   virtual bool operator==(const BreakIterator& o) const override { if(this==&o) return true; return false; }
 
   /* -- text modifying -- */
@@ -202,20 +202,20 @@ class SimpleFilteredSentenceBreakIterator : public BreakIterator {
 
   /* -- other functions that are just delegated -- */
   virtual UText *getUText(UText *fillIn, UErrorCode &status) const override { return fDelegate->getUText(fillIn,status); }
-  virtual CharacterIterator& getText(void) const override { return fDelegate->getText(); }
+  virtual CharacterIterator& getText() const override { return fDelegate->getText(); }
 
   /* -- ITERATION -- */
-  virtual int32_t first(void) override;
+  virtual int32_t first() override;
   virtual int32_t preceding(int32_t offset) override;
-  virtual int32_t previous(void) override;
+  virtual int32_t previous() override;
   virtual UBool isBoundary(int32_t offset) override;
-  virtual int32_t current(void) const override { return fDelegate->current(); } // we keep the delegate current, so this should be correct.
+  virtual int32_t current() const override { return fDelegate->current(); } // we keep the delegate current, so this should be correct.
 
-  virtual int32_t next(void) override;
+  virtual int32_t next() override;
 
   virtual int32_t next(int32_t n) override;
   virtual int32_t following(int32_t offset) override;
-  virtual int32_t last(void) override;
+  virtual int32_t last() override;
 
 private:
     /**
@@ -428,7 +428,7 @@ SimpleFilteredSentenceBreakIterator::next() {
 }
 
 int32_t
-SimpleFilteredSentenceBreakIterator::first(void) {
+SimpleFilteredSentenceBreakIterator::first() {
   // Don't suppress a break opportunity at the beginning of text.
   return fDelegate->first();
 }
@@ -439,7 +439,7 @@ SimpleFilteredSentenceBreakIterator::preceding(int32_t offset) {
 }
 
 int32_t
-SimpleFilteredSentenceBreakIterator::previous(void) {
+SimpleFilteredSentenceBreakIterator::previous() {
   return internalPrev(fDelegate->previous());
 }
 
@@ -473,7 +473,7 @@ SimpleFilteredSentenceBreakIterator::following(int32_t offset) {
 }
 
 int32_t
-SimpleFilteredSentenceBreakIterator::last(void) {
+SimpleFilteredSentenceBreakIterator::last() {
   // Don't suppress a break opportunity at the end of text.
   return fDelegate->last();
 }

icu4c/source/common/hash.h

@@ -97,7 +97,7 @@ class U_COMMON_API Hashtable : public UMemory {
 
     inline int32_t removei(const UnicodeString& key);
 
-    inline void removeAll(void);
+    inline void removeAll();
 
     inline UBool containsKey(const UnicodeString& key) const;
 
@@ -246,7 +246,7 @@ inline const UHashElement* Hashtable::nextElement(int32_t& pos) const {
     return uhash_nextElement(hash, &pos);
 }
 
-inline void Hashtable::removeAll(void) {
+inline void Hashtable::removeAll() {
     uhash_removeAll(hash);
 }
 

icu4c/source/common/icuplug.cpp

@@ -632,7 +632,7 @@ U_CAPI UPlugLevel U_EXPORT2 uplug_getCurrentLevel() {
   return gCurrentLevel;
 }
 
-static UBool U_CALLCONV uplug_cleanup(void)
+static UBool U_CALLCONV uplug_cleanup()
 {
   int32_t i;
 

icu4c/source/common/locavailable.cpp

@@ -43,7 +43,7 @@ U_NAMESPACE_END
 
 U_CDECL_BEGIN
 
-static UBool U_CALLCONV locale_available_cleanup(void)
+static UBool U_CALLCONV locale_available_cleanup()
 {
     U_NAMESPACE_USE
 
@@ -196,7 +196,7 @@ class AvailableLocalesStringEnumeration : public StringEnumeration {
 
 /* ### Get available **************************************************/
 
-static UBool U_CALLCONV uloc_cleanup(void) {
+static UBool U_CALLCONV uloc_cleanup() {
     for (int32_t i = 0; i < UPRV_LENGTHOF(gAvailableLocaleNames); i++) {
         uprv_free(gAvailableLocaleNames[i]);
         gAvailableLocaleNames[i] = nullptr;

icu4c/source/common/locdspnm.cpp

@@ -347,7 +347,7 @@ class LocaleDisplayNamesImpl : public LocaleDisplayNames {
     UnicodeString& keyDisplayName(const char* key, UnicodeString& result, UBool skipAdjust) const;
     UnicodeString& keyValueDisplayName(const char* key, const char* value,
                                         UnicodeString& result, UBool skipAdjust) const;
-    void initialize(void);
+    void initialize();
 
     struct CapitalizationContextSink;
 };
@@ -447,7 +447,7 @@ struct LocaleDisplayNamesImpl::CapitalizationContextSink : public ResourceSink {
 LocaleDisplayNamesImpl::CapitalizationContextSink::~CapitalizationContextSink() {}
 
 void
-LocaleDisplayNamesImpl::initialize(void) {
+LocaleDisplayNamesImpl::initialize() {
     LocaleDisplayNamesImpl *nonConstThis = (LocaleDisplayNamesImpl *)this;
     nonConstThis->locale = langData.getLocale() == Locale::getRoot()
         ? regionData.getLocale()