From 0bf8a95309992b7cb940fdf0629d3d58e3104861 Mon Sep 17 00:00:00 2001
From: Fredrik Roubert <roubert@google.com>
Date: Wed, 18 Sep 2024 20:42:13 +0200
Subject: [PATCH] ICU-22793 Remove superfluous return value typecasts to UBool.

---
 icu4c/source/common/bmpset.cpp                |  4 +-
 icu4c/source/common/bmpset.h                  |  2 +-
 icu4c/source/common/normalizer2impl.h         |  2 +-
 icu4c/source/common/patternprops.cpp          | 10 +--
 icu4c/source/common/putil.cpp                 | 12 ++--
 icu4c/source/common/ubidi_props.cpp           |  6 +-
 icu4c/source/common/ucase.cpp                 | 10 +--
 icu4c/source/common/uchar.cpp                 | 63 +++++++++----------
 icu4c/source/common/uchriter.cpp              |  4 +-
 icu4c/source/common/ucnv.cpp                  |  2 +-
 icu4c/source/common/ucnv_bld.cpp              |  4 +-
 icu4c/source/common/ucnv_io.cpp               |  6 +-
 icu4c/source/common/ucnv_u8.cpp               |  2 +-
 icu4c/source/common/ucnvisci.cpp              |  4 +-
 icu4c/source/common/ucnvmbcs.cpp              |  2 +-
 icu4c/source/common/ucnvscsu.cpp              |  4 +-
 icu4c/source/common/uhash.cpp                 |  8 +--
 icu4c/source/common/unames.cpp                |  6 +-
 icu4c/source/common/unicode/uniset.h          |  4 +-
 icu4c/source/common/unicode/unistr.h          |  8 +--
 icu4c/source/common/unicode/utypes.h          |  4 +-
 icu4c/source/common/uniset.cpp                |  6 +-
 icu4c/source/common/unisetspan.cpp            |  2 +-
 icu4c/source/common/unisetspan.h              |  4 +-
 icu4c/source/common/uprops.cpp                |  8 +--
 icu4c/source/common/uresbund.cpp              |  5 +-
 icu4c/source/common/uresdata.cpp              |  4 +-
 icu4c/source/common/uset.cpp                  |  4 +-
 icu4c/source/common/usprep.cpp                |  3 +-
 icu4c/source/common/ustr_wcs.cpp              |  2 +-
 icu4c/source/common/utrie.cpp                 |  2 +-
 icu4c/source/common/utrie2.cpp                |  2 +-
 icu4c/source/common/utrie2_builder.cpp        |  8 +--
 icu4c/source/i18n/calendar.cpp                |  2 +-
 icu4c/source/i18n/datefmt.cpp                 |  2 +-
 icu4c/source/i18n/dtptngen.cpp                |  4 +-
 icu4c/source/i18n/tznames_impl.h              |  2 +-
 icu4c/source/i18n/unicode/tblcoll.h           |  2 +-
 icu4c/source/io/ufmt_cmn.cpp                  |  2 +-
 icu4c/source/test/cintltst/chashtst.c         |  6 +-
 icu4c/source/test/cintltst/cintltst.c         |  2 +-
 icu4c/source/test/cintltst/crestst.c          |  2 +-
 icu4c/source/test/cintltst/creststn.c         |  2 +-
 icu4c/source/test/intltest/nptrans.cpp        |  2 +-
 icu4c/source/test/intltest/restest.cpp        |  4 +-
 icu4c/source/test/intltest/restsnew.cpp       |  2 +-
 icu4c/source/test/intltest/usettest.cpp       |  2 +-
 .../test/perf/unisetperf/draft/bitset.cpp     |  4 +-
 .../test/perf/unisetperf/draft/trieset.cpp    |  4 +-
 icu4c/source/tools/genrb/parse.cpp            |  2 +-
 icu4c/source/tools/gensprep/store.c           |  2 +-
 icu4c/source/tools/icupkg/icupkg.cpp          |  2 +-
 icu4c/source/tools/makeconv/genmbcs.cpp       |  2 +-
 icu4c/source/tools/toolutil/package.cpp       |  2 +-
 54 files changed, 133 insertions(+), 138 deletions(-)

diff --git a/icu4c/source/common/bmpset.cpp b/icu4c/source/common/bmpset.cpp
index bab4cff41728..9b2a2967f0dd 100644
--- a/icu4c/source/common/bmpset.cpp
+++ b/icu4c/source/common/bmpset.cpp
@@ -293,14 +293,14 @@ BMPSet::contains(UChar32 c) const {
     if (static_cast<uint32_t>(c) <= 0xff) {
         return latin1Contains[c];
     } else if (static_cast<uint32_t>(c) <= 0x7ff) {
-        return static_cast<UBool>((table7FF[c & 0x3f] & (static_cast<uint32_t>(1) << (c >> 6))) != 0);
+        return (table7FF[c & 0x3f] & (static_cast<uint32_t>(1) << (c >> 6))) != 0;
     } else if (static_cast<uint32_t>(c) < 0xd800 || (c >= 0xe000 && c <= 0xffff)) {
         int lead=c>>12;
         uint32_t twoBits=(bmpBlockBits[(c>>6)&0x3f]>>lead)&0x10001;
         if(twoBits<=1) {
             // All 64 code points with the same bits 15..6
             // are either in the set or not.
-            return static_cast<UBool>(twoBits);
+            return twoBits;
         } else {
             // Look up the code point in its 4k block of code points.
             return containsSlow(c, list4kStarts[lead], list4kStarts[lead+1]);
diff --git a/icu4c/source/common/bmpset.h b/icu4c/source/common/bmpset.h
index 440a7a81b087..00253f97c126 100644
--- a/icu4c/source/common/bmpset.h
+++ b/icu4c/source/common/bmpset.h
@@ -156,7 +156,7 @@ class BMPSet : public UMemory {
 };
 
 inline UBool BMPSet::containsSlow(UChar32 c, int32_t lo, int32_t hi) const {
-    return static_cast<UBool>(findCodePoint(c, lo, hi) & 1);
+    return findCodePoint(c, lo, hi) & 1;
 }
 
 U_NAMESPACE_END
diff --git a/icu4c/source/common/normalizer2impl.h b/icu4c/source/common/normalizer2impl.h
index 7bd733dee92e..5999190bae9b 100644
--- a/icu4c/source/common/normalizer2impl.h
+++ b/icu4c/source/common/normalizer2impl.h
@@ -364,7 +364,7 @@ class U_COMMON_API Normalizer2Impl : public UObject {
         // 0<=lead<=0xffff
         uint8_t bits=smallFCD[lead>>8];
         if(bits==0) { return false; }
-        return static_cast<UBool>((bits >> ((lead >> 5) & 7)) & 1);
+        return (bits >> ((lead >> 5) & 7)) & 1;
     }
     /** Returns the FCD value from the regular normalization data. */
     uint16_t getFCD16FromNormData(UChar32 c) const;
diff --git a/icu4c/source/common/patternprops.cpp b/icu4c/source/common/patternprops.cpp
index 19998574cc55..782d3366f93d 100644
--- a/icu4c/source/common/patternprops.cpp
+++ b/icu4c/source/common/patternprops.cpp
@@ -120,12 +120,12 @@ PatternProps::isSyntax(UChar32 c) {
     if(c<0) {
         return false;
     } else if(c<=0xff) {
-        return static_cast<UBool>(latin1[c] >> 1) & 1;
+        return (latin1[c] >> 1) & 1;
     } else if(c<0x2010) {
         return false;
     } else if(c<=0x3030) {
         uint32_t bits=syntax2000[index2000[(c-0x2000)>>5]];
-        return static_cast<UBool>((bits >> (c & 0x1f)) & 1);
+        return (bits >> (c & 0x1f)) & 1;
     } else if(0xfd3e<=c && c<=0xfe46) {
         return c<=0xfd3f || 0xfe45<=c;
     } else {
@@ -138,12 +138,12 @@ PatternProps::isSyntaxOrWhiteSpace(UChar32 c) {
     if(c<0) {
         return false;
     } else if(c<=0xff) {
-        return static_cast<UBool>(latin1[c] & 1);
+        return latin1[c] & 1;
     } else if(c<0x200e) {
         return false;
     } else if(c<=0x3030) {
         uint32_t bits=syntaxOrWhiteSpace2000[index2000[(c-0x2000)>>5]];
-        return static_cast<UBool>((bits >> (c & 0x1f)) & 1);
+        return (bits >> (c & 0x1f)) & 1;
     } else if(0xfd3e<=c && c<=0xfe46) {
         return c<=0xfd3f || 0xfe45<=c;
     } else {
@@ -156,7 +156,7 @@ PatternProps::isWhiteSpace(UChar32 c) {
     if(c<0) {
         return false;
     } else if(c<=0xff) {
-        return static_cast<UBool>(latin1[c] >> 2) & 1;
+        return (latin1[c] >> 2) & 1;
     } else if(0x200e<=c && c<=0x2029) {
         return c<=0x200f || 0x2028<=c;
     } else {
diff --git a/icu4c/source/common/putil.cpp b/icu4c/source/common/putil.cpp
index 718bbb3d371a..4cf07797ba35 100644
--- a/icu4c/source/common/putil.cpp
+++ b/icu4c/source/common/putil.cpp
@@ -342,7 +342,7 @@ uprv_isNaN(double number)
     BitPatternConversion convertedNumber;
     convertedNumber.d64 = number;
     /* Infinity is 0x7FF0000000000000U. Anything greater than that is a NaN */
-    return (UBool)((convertedNumber.i64 & U_INT64_MAX) > gInf.i64);
+    return (convertedNumber.i64 & U_INT64_MAX) > gInf.i64;
 
 #elif U_PLATFORM == U_PF_OS390
     uint32_t highBits = *(uint32_t*)u_topNBytesOfDouble(&number,
@@ -368,7 +368,7 @@ uprv_isInfinite(double number)
     BitPatternConversion convertedNumber;
     convertedNumber.d64 = number;
     /* Infinity is exactly 0x7FF0000000000000U. */
-    return (UBool)((convertedNumber.i64 & U_INT64_MAX) == gInf.i64);
+    return (convertedNumber.i64 & U_INT64_MAX) == gInf.i64;
 #elif U_PLATFORM == U_PF_OS390
     uint32_t highBits = *(uint32_t*)u_topNBytesOfDouble(&number,
                         sizeof(uint32_t));
@@ -389,7 +389,7 @@ U_CAPI UBool U_EXPORT2
 uprv_isPositiveInfinity(double number)
 {
 #if IEEE_754 || U_PLATFORM == U_PF_OS390
-    return (UBool)(number > 0 && uprv_isInfinite(number));
+    return number > 0 && uprv_isInfinite(number);
 #else
     return uprv_isInfinite(number);
 #endif
@@ -399,7 +399,7 @@ U_CAPI UBool U_EXPORT2
 uprv_isNegativeInfinity(double number)
 {
 #if IEEE_754 || U_PLATFORM == U_PF_OS390
-    return (UBool)(number < 0 && uprv_isInfinite(number));
+    return number < 0 && uprv_isInfinite(number);
 
 #else
     uint32_t highBits = *(uint32_t*)u_topNBytesOfDouble(&number,
@@ -744,11 +744,11 @@ static UBool isValidOlsonID(const char *id) {
     The timezone is sometimes set to "CST-7CDT", "CST6CDT5,J129,J131/19:30",
     "GRNLNDST3GRNLNDDT" or similar, so we cannot use it.
     The rest of the time it could be an Olson ID. George */
-    return static_cast<UBool>(id[idx] == 0
+    return id[idx] == 0
         || uprv_strcmp(id, "PST8PDT") == 0
         || uprv_strcmp(id, "MST7MDT") == 0
         || uprv_strcmp(id, "CST6CDT") == 0
-        || uprv_strcmp(id, "EST5EDT") == 0);
+        || uprv_strcmp(id, "EST5EDT") == 0;
 }
 
 /* On some Unix-like OS, 'posix' subdirectory in
diff --git a/icu4c/source/common/ubidi_props.cpp b/icu4c/source/common/ubidi_props.cpp
index 80044cca5413..1ac4ab12a2c3 100644
--- a/icu4c/source/common/ubidi_props.cpp
+++ b/icu4c/source/common/ubidi_props.cpp
@@ -139,7 +139,7 @@ ubidi_getClass(UChar32 c) {
 U_CFUNC UBool
 ubidi_isMirrored(UChar32 c) {
     uint16_t props=UTRIE2_GET16(&ubidi_props_singleton.trie, c);
-    return (UBool)UBIDI_GET_FLAG(props, UBIDI_IS_MIRRORED_SHIFT);
+    return UBIDI_GET_FLAG(props, UBIDI_IS_MIRRORED_SHIFT);
 }
 
 static UChar32
@@ -183,13 +183,13 @@ ubidi_getMirror(UChar32 c) {
 U_CFUNC UBool
 ubidi_isBidiControl(UChar32 c) {
     uint16_t props=UTRIE2_GET16(&ubidi_props_singleton.trie, c);
-    return (UBool)UBIDI_GET_FLAG(props, UBIDI_BIDI_CONTROL_SHIFT);
+    return UBIDI_GET_FLAG(props, UBIDI_BIDI_CONTROL_SHIFT);
 }
 
 U_CFUNC UBool
 ubidi_isJoinControl(UChar32 c) {
     uint16_t props=UTRIE2_GET16(&ubidi_props_singleton.trie, c);
-    return (UBool)UBIDI_GET_FLAG(props, UBIDI_JOIN_CONTROL_SHIFT);
+    return UBIDI_GET_FLAG(props, UBIDI_JOIN_CONTROL_SHIFT);
 }
 
 U_CFUNC UJoiningType
diff --git a/icu4c/source/common/ucase.cpp b/icu4c/source/common/ucase.cpp
index 40b43cd89275..5a2feaee840b 100644
--- a/icu4c/source/common/ucase.cpp
+++ b/icu4c/source/common/ucase.cpp
@@ -696,17 +696,17 @@ getDotType(UChar32 c) {
 
 U_CAPI UBool U_EXPORT2
 ucase_isSoftDotted(UChar32 c) {
-    return (UBool)(getDotType(c)==UCASE_SOFT_DOTTED);
+    return getDotType(c)==UCASE_SOFT_DOTTED;
 }
 
 U_CAPI UBool U_EXPORT2
 ucase_isCaseSensitive(UChar32 c) {
     uint16_t props=UTRIE2_GET16(&ucase_props_singleton.trie, c);
     if(!UCASE_HAS_EXCEPTION(props)) {
-        return (UBool)((props&UCASE_SENSITIVE)!=0);
+        return (props&UCASE_SENSITIVE)!=0;
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(&ucase_props_singleton, props);
-        return (UBool)((*pe&UCASE_EXC_SENSITIVE)!=0);
+        return (*pe&UCASE_EXC_SENSITIVE)!=0;
     }
 }
 
@@ -1623,12 +1623,12 @@ ucase_toFullFolding(UChar32 c,
 
 U_CAPI UBool U_EXPORT2
 u_isULowercase(UChar32 c) {
-    return (UBool)(UCASE_LOWER==ucase_getType(c));
+    return UCASE_LOWER==ucase_getType(c);
 }
 
 U_CAPI UBool U_EXPORT2
 u_isUUppercase(UChar32 c) {
-    return (UBool)(UCASE_UPPER==ucase_getType(c));
+    return UCASE_UPPER==ucase_getType(c);
 }
 
 /* Transforms the Unicode character to its lower case equivalent.*/
diff --git a/icu4c/source/common/uchar.cpp b/icu4c/source/common/uchar.cpp
index f22d861c96e9..3b2ae8c8af5d 100644
--- a/icu4c/source/common/uchar.cpp
+++ b/icu4c/source/common/uchar.cpp
@@ -91,7 +91,7 @@ U_CAPI UBool U_EXPORT2
 u_islower(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)==U_LOWERCASE_LETTER);
+    return GET_CATEGORY(props)==U_LOWERCASE_LETTER;
 }
 
 /* Checks if ch is an upper case letter.*/
@@ -99,7 +99,7 @@ U_CAPI UBool U_EXPORT2
 u_isupper(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)==U_UPPERCASE_LETTER);
+    return GET_CATEGORY(props)==U_UPPERCASE_LETTER;
 }
 
 /* Checks if ch is a title case letter; usually upper case letters.*/
@@ -107,7 +107,7 @@ U_CAPI UBool U_EXPORT2
 u_istitle(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)==U_TITLECASE_LETTER);
+    return GET_CATEGORY(props)==U_TITLECASE_LETTER;
 }
 
 /* Checks if ch is a decimal digit. */
@@ -115,7 +115,7 @@ U_CAPI UBool U_EXPORT2
 u_isdigit(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)==U_DECIMAL_DIGIT_NUMBER);
+    return GET_CATEGORY(props)==U_DECIMAL_DIGIT_NUMBER;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -131,7 +131,7 @@ u_isxdigit(UChar32 c) {
     }
 
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)==U_DECIMAL_DIGIT_NUMBER);
+    return GET_CATEGORY(props)==U_DECIMAL_DIGIT_NUMBER;
 }
 
 /* Checks if the Unicode character is a letter.*/
@@ -139,7 +139,7 @@ U_CAPI UBool U_EXPORT2
 u_isalpha(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&U_GC_L_MASK)!=0);
+    return (CAT_MASK(props)&U_GC_L_MASK)!=0;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -152,7 +152,7 @@ U_CAPI UBool U_EXPORT2
 u_isalnum(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&(U_GC_L_MASK|U_GC_ND_MASK))!=0);
+    return (CAT_MASK(props)&(U_GC_L_MASK|U_GC_ND_MASK))!=0;
 }
 
 /**
@@ -161,7 +161,7 @@ u_isalnum(UChar32 c) {
  */
 U_CFUNC UBool
 u_isalnumPOSIX(UChar32 c) {
-    return (UBool)(u_isUAlphabetic(c) || u_isdigit(c));
+    return u_isUAlphabetic(c) || u_isdigit(c);
 }
 
 /* Checks if ch is a unicode character with assigned character type.*/
@@ -169,7 +169,7 @@ U_CAPI UBool U_EXPORT2
 u_isdefined(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(GET_CATEGORY(props)!=0);
+    return GET_CATEGORY(props)!=0;
 }
 
 /* Checks if the Unicode character is a base form character that can take a diacritic.*/
@@ -177,7 +177,7 @@ U_CAPI UBool U_EXPORT2
 u_isbase(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&(U_GC_L_MASK|U_GC_N_MASK|U_GC_MC_MASK|U_GC_ME_MASK))!=0);
+    return (CAT_MASK(props)&(U_GC_L_MASK|U_GC_N_MASK|U_GC_MC_MASK|U_GC_ME_MASK))!=0;
 }
 
 /* Checks if the Unicode character is a control character.*/
@@ -185,7 +185,7 @@ U_CAPI UBool U_EXPORT2
 u_iscntrl(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&(U_GC_CC_MASK|U_GC_CF_MASK|U_GC_ZL_MASK|U_GC_ZP_MASK))!=0);
+    return (CAT_MASK(props)&(U_GC_CC_MASK|U_GC_CF_MASK|U_GC_ZL_MASK|U_GC_ZP_MASK))!=0;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -206,14 +206,14 @@ U_CAPI UBool U_EXPORT2
 u_isspace(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&U_GC_Z_MASK)!=0 || IS_THAT_CONTROL_SPACE(c));
+    return (CAT_MASK(props)&U_GC_Z_MASK)!=0 || IS_THAT_CONTROL_SPACE(c);
 }
 
 U_CAPI UBool U_EXPORT2
 u_isJavaSpaceChar(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&U_GC_Z_MASK)!=0);
+    return (CAT_MASK(props)&U_GC_Z_MASK)!=0;
 }
 
 /* Checks if the Unicode character is a whitespace character.*/
@@ -221,11 +221,9 @@ U_CAPI UBool U_EXPORT2
 u_isWhitespace(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(
-                ((CAT_MASK(props)&U_GC_Z_MASK)!=0 &&
-                    c!=NBSP && c!=FIGURESP && c!=NNBSP) || /* exclude no-break spaces */
-                IS_THAT_ASCII_CONTROL_SPACE(c)
-           );
+    return ((CAT_MASK(props)&U_GC_Z_MASK)!=0 &&
+               c!=NBSP && c!=FIGURESP && c!=NNBSP) || /* exclude no-break spaces */
+           IS_THAT_ASCII_CONTROL_SPACE(c);
 }
 
 U_CAPI UBool U_EXPORT2
@@ -236,7 +234,7 @@ u_isblank(UChar32 c) {
         /* Zs */
         uint32_t props;
         GET_PROPS(c, props);
-        return (UBool)(GET_CATEGORY(props)==U_SPACE_SEPARATOR);
+        return GET_CATEGORY(props)==U_SPACE_SEPARATOR;
     }
 }
 
@@ -251,7 +249,7 @@ u_isprint(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
     /* comparing ==0 returns false for the categories mentioned */
-    return (UBool)((CAT_MASK(props)&U_GC_C_MASK)==0);
+    return (CAT_MASK(props)&U_GC_C_MASK)==0;
 }
 
 /**
@@ -267,7 +265,7 @@ u_isprintPOSIX(UChar32 c) {
      * The only cntrl character in graph+blank is TAB (in blank).
      * Here we implement (blank-TAB)=Zs instead of calling u_isblank().
      */
-    return (UBool)((GET_CATEGORY(props)==U_SPACE_SEPARATOR) || u_isgraphPOSIX(c));
+    return (GET_CATEGORY(props)==U_SPACE_SEPARATOR) || u_isgraphPOSIX(c);
 }
 
 U_CAPI UBool U_EXPORT2
@@ -275,9 +273,9 @@ u_isgraph(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
     /* comparing ==0 returns false for the categories mentioned */
-    return (UBool)((CAT_MASK(props)&
-                    (U_GC_CC_MASK|U_GC_CF_MASK|U_GC_CS_MASK|U_GC_CN_MASK|U_GC_Z_MASK))
-                   ==0);
+    return (CAT_MASK(props)&
+            (U_GC_CC_MASK|U_GC_CF_MASK|U_GC_CS_MASK|U_GC_CN_MASK|U_GC_Z_MASK))
+           ==0;
 }
 
 /**
@@ -293,16 +291,16 @@ u_isgraphPOSIX(UChar32 c) {
     GET_PROPS(c, props);
     /* \p{space}\p{gc=Control} == \p{gc=Z}\p{Control} */
     /* comparing ==0 returns false for the categories mentioned */
-    return (UBool)((CAT_MASK(props)&
-                    (U_GC_CC_MASK|U_GC_CS_MASK|U_GC_CN_MASK|U_GC_Z_MASK))
-                   ==0);
+    return (CAT_MASK(props)&
+            (U_GC_CC_MASK|U_GC_CS_MASK|U_GC_CN_MASK|U_GC_Z_MASK))
+           ==0;
 }
 
 U_CAPI UBool U_EXPORT2
 u_ispunct(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&U_GC_P_MASK)!=0);
+    return (CAT_MASK(props)&U_GC_P_MASK)!=0;
 }
 
 /*Checks if the Unicode character can be ignorable in a Java or Unicode identifier.*/
@@ -313,7 +311,7 @@ u_isIDIgnorable(UChar32 c) {
     } else {
         uint32_t props;
         GET_PROPS(c, props);
-        return (UBool)(GET_CATEGORY(props)==U_FORMAT_CHAR);
+        return GET_CATEGORY(props)==U_FORMAT_CHAR;
     }
 }
 
@@ -322,7 +320,7 @@ U_CAPI UBool U_EXPORT2
 u_isJavaIDStart(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)((CAT_MASK(props)&(U_GC_L_MASK|U_GC_SC_MASK|U_GC_PC_MASK))!=0);
+    return (CAT_MASK(props)&(U_GC_L_MASK|U_GC_SC_MASK|U_GC_PC_MASK))!=0;
 }
 
 /*Checks if the Unicode character can be a Java identifier part other than starting the
@@ -332,14 +330,13 @@ U_CAPI UBool U_EXPORT2
 u_isJavaIDPart(UChar32 c) {
     uint32_t props;
     GET_PROPS(c, props);
-    return (UBool)(
-           (CAT_MASK(props)&
+    return (CAT_MASK(props)&
             (U_GC_ND_MASK|U_GC_NL_MASK|
              U_GC_L_MASK|
              U_GC_SC_MASK|U_GC_PC_MASK|
              U_GC_MC_MASK|U_GC_MN_MASK)
            )!=0 ||
-           u_isIDIgnorable(c));
+           u_isIDIgnorable(c);
 }
 
 U_CAPI int32_t U_EXPORT2
diff --git a/icu4c/source/common/uchriter.cpp b/icu4c/source/common/uchriter.cpp
index b3402989011b..903eb46c3b34 100644
--- a/icu4c/source/common/uchriter.cpp
+++ b/icu4c/source/common/uchriter.cpp
@@ -172,7 +172,7 @@ UCharCharacterIterator::nextPostInc() {
 
 UBool
 UCharCharacterIterator::hasNext() {
-    return static_cast<UBool>(pos < end);
+    return pos < end;
 }
 
 char16_t
@@ -186,7 +186,7 @@ UCharCharacterIterator::previous() {
 
 UBool
 UCharCharacterIterator::hasPrevious() {
-    return static_cast<UBool>(pos > begin);
+    return pos > begin;
 }
 
 UChar32
diff --git a/icu4c/source/common/ucnv.cpp b/icu4c/source/common/ucnv.cpp
index 2ea88cca691a..c66200b79323 100644
--- a/icu4c/source/common/ucnv.cpp
+++ b/icu4c/source/common/ucnv.cpp
@@ -2684,7 +2684,7 @@ ucnv_fixFileSeparator(const UConverter *cnv,
 
 U_CAPI UBool  U_EXPORT2
 ucnv_isAmbiguous(const UConverter *cnv) {
-    return (UBool)(ucnv_getAmbiguous(cnv)!=nullptr);
+    return ucnv_getAmbiguous(cnv)!=nullptr;
 }
 
 U_CAPI void  U_EXPORT2
diff --git a/icu4c/source/common/ucnv_bld.cpp b/icu4c/source/common/ucnv_bld.cpp
index eb7ae1eaa9da..8dc166cd5b55 100644
--- a/icu4c/source/common/ucnv_bld.cpp
+++ b/icu4c/source/common/ucnv_bld.cpp
@@ -270,7 +270,7 @@ static UBool U_CALLCONV
 isCnvAcceptable(void * /*context*/,
                 const char * /*type*/, const char * /*name*/,
                 const UDataInfo *pInfo) {
-    return static_cast<UBool>(
+    return
         pInfo->size>=20 &&
         pInfo->isBigEndian==U_IS_BIG_ENDIAN &&
         pInfo->charsetFamily==U_CHARSET_FAMILY &&
@@ -279,7 +279,7 @@ isCnvAcceptable(void * /*context*/,
         pInfo->dataFormat[1]==0x6e &&
         pInfo->dataFormat[2]==0x76 &&
         pInfo->dataFormat[3]==0x74 &&
-        pInfo->formatVersion[0]==6);  /* Everything will be version 6 */
+        pInfo->formatVersion[0]==6;  /* Everything will be version 6 */
 }
 
 /**
diff --git a/icu4c/source/common/ucnv_io.cpp b/icu4c/source/common/ucnv_io.cpp
index abd19022ebb3..7207de397eb1 100644
--- a/icu4c/source/common/ucnv_io.cpp
+++ b/icu4c/source/common/ucnv_io.cpp
@@ -205,7 +205,7 @@ static UBool U_CALLCONV
 isAcceptable(void * /*context*/,
              const char * /*type*/, const char * /*name*/,
              const UDataInfo *pInfo) {
-    return static_cast<UBool>(
+    return
         pInfo->size>=20 &&
         pInfo->isBigEndian==U_IS_BIG_ENDIAN &&
         pInfo->charsetFamily==U_CHARSET_FAMILY &&
@@ -213,7 +213,7 @@ isAcceptable(void * /*context*/,
         pInfo->dataFormat[1]==0x76 &&
         pInfo->dataFormat[2]==0x41 &&
         pInfo->dataFormat[3]==0x6c &&
-        pInfo->formatVersion[0]==3);
+        pInfo->formatVersion[0]==3;
 }
 
 static UBool U_CALLCONV ucnv_io_cleanup()
@@ -321,7 +321,7 @@ isAlias(const char *alias, UErrorCode *pErrorCode) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return false;
     }
-    return static_cast<UBool>(*alias != 0);
+    return *alias != 0;
 }
 
 static uint32_t getTagNumber(const char *tagname) {
diff --git a/icu4c/source/common/ucnv_u8.cpp b/icu4c/source/common/ucnv_u8.cpp
index 18c57c61482a..cca6e603ae32 100644
--- a/icu4c/source/common/ucnv_u8.cpp
+++ b/icu4c/source/common/ucnv_u8.cpp
@@ -58,7 +58,7 @@ static UBool hasCESU8Data(const UConverter *cnv)
 #if UCONFIG_ONLY_HTML_CONVERSION
     return false;
 #else
-    return static_cast<UBool>(cnv->sharedData == &_CESU8Data);
+    return cnv->sharedData == &_CESU8Data;
 #endif
 }
 U_CDECL_BEGIN
diff --git a/icu4c/source/common/ucnvisci.cpp b/icu4c/source/common/ucnvisci.cpp
index 9f3a8125e28d..c5f5832dcfcc 100644
--- a/icu4c/source/common/ucnvisci.cpp
+++ b/icu4c/source/common/ucnvisci.cpp
@@ -174,7 +174,7 @@ isPNJConsonant(UChar32 c) {
     if (c < 0xa00 || 0xa50 <= c) {
         return false;
     } else {
-        return static_cast<UBool>(pnjMap[c - 0xa00] & 1);
+        return pnjMap[c - 0xa00] & 1;
     }
 }
 
@@ -183,7 +183,7 @@ isPNJBindiTippi(UChar32 c) {
     if (c < 0xa00 || 0xa50 <= c) {
         return false;
     } else {
-        return static_cast<UBool>(pnjMap[c - 0xa00] >> 1);
+        return pnjMap[c - 0xa00] >> 1;
     }
 }
 U_CDECL_BEGIN
diff --git a/icu4c/source/common/ucnvmbcs.cpp b/icu4c/source/common/ucnvmbcs.cpp
index 6b4d1491a2a6..e20dc984155a 100644
--- a/icu4c/source/common/ucnvmbcs.cpp
+++ b/icu4c/source/common/ucnvmbcs.cpp
@@ -5644,7 +5644,7 @@ ucnv_MBCSGetStarters(const UConverter* cnv,
  */
 U_CFUNC UBool
 ucnv_MBCSIsLeadByte(UConverterSharedData *sharedData, char byte) {
-    return (UBool)MBCS_ENTRY_IS_TRANSITION(sharedData->mbcs.stateTable[0][(uint8_t)byte]);
+    return MBCS_ENTRY_IS_TRANSITION(sharedData->mbcs.stateTable[0][(uint8_t)byte]);
 }
 
 static void U_CALLCONV
diff --git a/icu4c/source/common/ucnvscsu.cpp b/icu4c/source/common/ucnvscsu.cpp
index 6dd1654636a1..5412136a346a 100644
--- a/icu4c/source/common/ucnvscsu.cpp
+++ b/icu4c/source/common/ucnvscsu.cpp
@@ -893,9 +893,9 @@ getWindow(const uint32_t offsets[8], uint32_t c) {
 /* is the character in the dynamic window starting at the offset, or in the direct-encoded range? */
 static UBool
 isInOffsetWindowOrDirect(uint32_t offset, uint32_t c) {
-    return static_cast<UBool>(c<=offset+0x7f &&
+    return c<=offset+0x7f &&
           (c>=offset || (c<=0x7f &&
-                        (c>=0x20 || (1UL<<c)&0x2601))));
+                        (c>=0x20 || (1UL<<c)&0x2601)));
                                 /* binary 0010 0110 0000 0001,
                                    check for b==0xd || b==0xa || b==9 || b==0 */
 }
diff --git a/icu4c/source/common/uhash.cpp b/icu4c/source/common/uhash.cpp
index c2eb02fbfbd1..02dc3d047897 100644
--- a/icu4c/source/common/uhash.cpp
+++ b/icu4c/source/common/uhash.cpp
@@ -1022,7 +1022,7 @@ uhash_compareUChars(const UHashTok key1, const UHashTok key2) {
         ++p1;
         ++p2;
     }
-    return (UBool)(*p1 == *p2);
+    return *p1 == *p2;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -1039,7 +1039,7 @@ uhash_compareChars(const UHashTok key1, const UHashTok key2) {
         ++p1;
         ++p2;
     }
-    return (UBool)(*p1 == *p2);
+    return *p1 == *p2;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -1056,7 +1056,7 @@ uhash_compareIChars(const UHashTok key1, const UHashTok key2) {
         ++p1;
         ++p2;
     }
-    return (UBool)(*p1 == *p2);
+    return *p1 == *p2;
 }
 
 U_CAPI UBool U_EXPORT2
@@ -1093,5 +1093,5 @@ uhash_hashLong(const UHashTok key) {
 
 U_CAPI UBool U_EXPORT2
 uhash_compareLong(const UHashTok key1, const UHashTok key2) {
-    return (UBool)(key1.integer == key2.integer);
+    return key1.integer == key2.integer;
 }
diff --git a/icu4c/source/common/unames.cpp b/icu4c/source/common/unames.cpp
index 89dbcc88286a..71b2baff6c19 100644
--- a/icu4c/source/common/unames.cpp
+++ b/icu4c/source/common/unames.cpp
@@ -180,7 +180,7 @@ static UBool U_CALLCONV
 isAcceptable(void * /*context*/,
              const char * /*type*/, const char * /*name*/,
              const UDataInfo *pInfo) {
-    return static_cast<UBool>(
+    return
         pInfo->size>=20 &&
         pInfo->isBigEndian==U_IS_BIG_ENDIAN &&
         pInfo->charsetFamily==U_CHARSET_FAMILY &&
@@ -188,7 +188,7 @@ isAcceptable(void * /*context*/,
         pInfo->dataFormat[1]==0x6e &&
         pInfo->dataFormat[2]==0x61 &&
         pInfo->dataFormat[3]==0x6d &&
-        pInfo->formatVersion[0]==1);
+        pInfo->formatVersion[0]==1;
 }
 
 static void U_CALLCONV
@@ -415,7 +415,7 @@ compareName(UCharNames *names,
     }
 
     /* complete match? */
-    return static_cast<UBool>(*otherName == 0);
+    return *otherName == 0;
 }
 
 static uint8_t getCharCat(UChar32 cp) {
diff --git a/icu4c/source/common/unicode/uniset.h b/icu4c/source/common/unicode/uniset.h
index c45f93d19674..d070fd631a22 100644
--- a/icu4c/source/common/unicode/uniset.h
+++ b/icu4c/source/common/unicode/uniset.h
@@ -1843,7 +1843,7 @@ inline bool UnicodeSet::operator!=(const UnicodeSet& o) const {
 }
 
 inline UBool UnicodeSet::isFrozen() const {
-    return static_cast<UBool>(bmpSet != nullptr || stringSpan != nullptr);
+    return bmpSet != nullptr || stringSpan != nullptr;
 }
 
 inline UBool UnicodeSet::containsSome(UChar32 start, UChar32 end) const {
@@ -1859,7 +1859,7 @@ inline UBool UnicodeSet::containsSome(const UnicodeString& s) const {
 }
 
 inline UBool UnicodeSet::isBogus() const {
-    return static_cast<UBool>(fFlags & kIsBogus);
+    return fFlags & kIsBogus;
 }
 
 inline UnicodeSet *UnicodeSet::fromUSet(USet *uset) {
diff --git a/icu4c/source/common/unicode/unistr.h b/icu4c/source/common/unicode/unistr.h
index a65d467c07dc..a0a4f0021ff6 100644
--- a/icu4c/source/common/unicode/unistr.h
+++ b/icu4c/source/common/unicode/unistr.h
@@ -4227,18 +4227,18 @@ UnicodeString::hashCode() const
 
 inline UBool
 UnicodeString::isBogus() const
-{ return static_cast<UBool>(fUnion.fFields.fLengthAndFlags & kIsBogus); }
+{ return fUnion.fFields.fLengthAndFlags & kIsBogus; }
 
 inline UBool
 UnicodeString::isWritable() const
-{ return static_cast<UBool>(!(fUnion.fFields.fLengthAndFlags & (kOpenGetBuffer | kIsBogus))); }
+{ return !(fUnion.fFields.fLengthAndFlags & (kOpenGetBuffer | kIsBogus)); }
 
 inline UBool
 UnicodeString::isBufferWritable() const
 {
-  return static_cast<UBool>(
+  return
       !(fUnion.fFields.fLengthAndFlags&(kOpenGetBuffer|kIsBogus|kBufferIsReadonly)) &&
-      (!(fUnion.fFields.fLengthAndFlags&kRefCounted) || refCount()==1));
+      (!(fUnion.fFields.fLengthAndFlags&kRefCounted) || refCount()==1);
 }
 
 inline const char16_t *
diff --git a/icu4c/source/common/unicode/utypes.h b/icu4c/source/common/unicode/utypes.h
index fcec29546af7..87fa5ddf7e87 100644
--- a/icu4c/source/common/unicode/utypes.h
+++ b/icu4c/source/common/unicode/utypes.h
@@ -729,13 +729,13 @@ typedef enum UErrorCode {
      * @stable ICU 2.0
      */
     static
-    inline UBool U_SUCCESS(UErrorCode code) { return static_cast<UBool>(code <= U_ZERO_ERROR); }
+    inline UBool U_SUCCESS(UErrorCode code) { return code <= U_ZERO_ERROR; }
     /**
      * Does the error code indicate a failure?
      * @stable ICU 2.0
      */
     static
-    inline UBool U_FAILURE(UErrorCode code) { return static_cast<UBool>(code > U_ZERO_ERROR); }
+    inline UBool U_FAILURE(UErrorCode code) { return code > U_ZERO_ERROR; }
 #else
     /**
      * Does the error code indicate success?
diff --git a/icu4c/source/common/uniset.cpp b/icu4c/source/common/uniset.cpp
index ef78ce33b195..2d6610cb355d 100644
--- a/icu4c/source/common/uniset.cpp
+++ b/icu4c/source/common/uniset.cpp
@@ -355,7 +355,7 @@ UBool UnicodeSet::contains(UChar32 c) const {
         return false;
     }
     int32_t i = findCodePoint(c);
-    return static_cast<UBool>(i & 1); // return true if odd
+    return i & 1; // return true if odd
 }
 
 /**
@@ -460,7 +460,7 @@ UBool UnicodeSet::containsAll(const UnicodeSet& c) const {
  * @return true if the test condition is met
  */
 UBool UnicodeSet::containsAll(const UnicodeString& s) const {
-    return static_cast<UBool>(span(s.getBuffer(), s.length(), USET_SPAN_CONTAINED) == s.length());
+    return span(s.getBuffer(), s.length(), USET_SPAN_CONTAINED) == s.length();
 }
 
 /**
@@ -505,7 +505,7 @@ UBool UnicodeSet::containsNone(const UnicodeSet& c) const {
  * @return true if the test condition is met
  */
 UBool UnicodeSet::containsNone(const UnicodeString& s) const {
-    return static_cast<UBool>(span(s.getBuffer(), s.length(), USET_SPAN_NOT_CONTAINED) == s.length());
+    return span(s.getBuffer(), s.length(), USET_SPAN_NOT_CONTAINED) == s.length();
 }
 
 /**
diff --git a/icu4c/source/common/unisetspan.cpp b/icu4c/source/common/unisetspan.cpp
index dc4e89e5ca4a..209f0a86b541 100644
--- a/icu4c/source/common/unisetspan.cpp
+++ b/icu4c/source/common/unisetspan.cpp
@@ -84,7 +84,7 @@ class OffsetList {  // Only ever stack-allocated, does not need to inherit UMemo
     }
 
     UBool isEmpty() const {
-        return static_cast<UBool>(length == 0);
+        return length == 0;
     }
 
     // Reduce all stored offsets by delta, used when the current position
diff --git a/icu4c/source/common/unisetspan.h b/icu4c/source/common/unisetspan.h
index ecf8a9b00ffc..482782ebf75e 100644
--- a/icu4c/source/common/unisetspan.h
+++ b/icu4c/source/common/unisetspan.h
@@ -141,11 +141,11 @@ class UnicodeSetStringSpan : public UMemory {
 };
 
 UBool UnicodeSetStringSpan::needsStringSpanUTF16() {
-    return static_cast<UBool>(maxLength16 != 0);
+    return maxLength16 != 0;
 }
 
 UBool UnicodeSetStringSpan::needsStringSpanUTF8() {
-    return static_cast<UBool>(maxLength8 != 0);
+    return maxLength8 != 0;
 }
 
 UBool UnicodeSetStringSpan::contains(UChar32 c) const {
diff --git a/icu4c/source/common/uprops.cpp b/icu4c/source/common/uprops.cpp
index 36aaba698d05..0f80d742d657 100644
--- a/icu4c/source/common/uprops.cpp
+++ b/icu4c/source/common/uprops.cpp
@@ -171,7 +171,7 @@ static UBool defaultContains(const BinaryProperty &prop, UChar32 c, UProperty /*
 }
 
 static UBool caseBinaryPropertyContains(const BinaryProperty &/*prop*/, UChar32 c, UProperty which) {
-    return static_cast<UBool>(ucase_hasBinaryProperty(c, which));
+    return ucase_hasBinaryProperty(c, which);
 }
 
 static UBool isBidiControl(const BinaryProperty &/*prop*/, UChar32 c, UProperty /*which*/) {
@@ -242,7 +242,7 @@ static UBool changesWhenCasefolded(const BinaryProperty &/*prop*/, UChar32 c, UP
     if(c>=0) {
         /* single code point */
         const char16_t *resultString;
-        return static_cast<UBool>(ucase_toFullFolding(c, &resultString, U_FOLD_CASE_DEFAULT) >= 0);
+        return ucase_toFullFolding(c, &resultString, U_FOLD_CASE_DEFAULT) >= 0;
     } else {
         /* guess some large but stack-friendly capacity */
         char16_t dest[2*UCASE_MAX_STRING_LENGTH];
@@ -250,9 +250,9 @@ static UBool changesWhenCasefolded(const BinaryProperty &/*prop*/, UChar32 c, UP
         destLength=u_strFoldCase(dest, UPRV_LENGTHOF(dest),
                                   nfd.getBuffer(), nfd.length(),
                                   U_FOLD_CASE_DEFAULT, &errorCode);
-        return static_cast<UBool>(U_SUCCESS(errorCode) &&
+        return U_SUCCESS(errorCode) &&
                        0!=u_strCompare(nfd.getBuffer(), nfd.length(),
-                                       dest, destLength, false));
+                                       dest, destLength, false);
     }
 }
 #endif
diff --git a/icu4c/source/common/uresbund.cpp b/icu4c/source/common/uresbund.cpp
index cfe2f4a4d20f..3a09cbf3bcaa 100644
--- a/icu4c/source/common/uresbund.cpp
+++ b/icu4c/source/common/uresbund.cpp
@@ -72,8 +72,7 @@ static UBool U_CALLCONV compareEntries(const UHashTok p1, const UHashTok p2) {
     name2.pointer = b2->fName;
     path1.pointer = b1->fPath;
     path2.pointer = b2->fPath;
-    return static_cast<UBool>(uhash_compareChars(name1, name2) &&
-        uhash_compareChars(path1, path2));
+    return uhash_compareChars(name1, name2) && uhash_compareChars(path1, path2);
 }
 
 
@@ -1730,7 +1729,7 @@ U_CAPI UBool U_EXPORT2 ures_hasNext(const UResourceBundle *resB) {
   if(resB == nullptr) {
     return false;
   }
-  return (UBool)(resB->fIndex < resB->fSize-1);
+  return resB->fIndex < resB->fSize-1;
 }
 
 U_CAPI const char16_t* U_EXPORT2 ures_getNextString(UResourceBundle *resB, int32_t* len, const char ** key, UErrorCode *status) {
diff --git a/icu4c/source/common/uresdata.cpp b/icu4c/source/common/uresdata.cpp
index 896e4ed1d6f1..11faddf1ade9 100644
--- a/icu4c/source/common/uresdata.cpp
+++ b/icu4c/source/common/uresdata.cpp
@@ -140,7 +140,7 @@ isAcceptable(void *context,
              const char * /*type*/, const char * /*name*/,
              const UDataInfo *pInfo) {
     uprv_memcpy(context, pInfo->formatVersion, 4);
-    return static_cast<UBool>(
+    return
         pInfo->size>=20 &&
         pInfo->isBigEndian==U_IS_BIG_ENDIAN &&
         pInfo->charsetFamily==U_CHARSET_FAMILY &&
@@ -149,7 +149,7 @@ isAcceptable(void *context,
         pInfo->dataFormat[1]==0x65 &&
         pInfo->dataFormat[2]==0x73 &&
         pInfo->dataFormat[3]==0x42 &&
-        (1<=pInfo->formatVersion[0] && pInfo->formatVersion[0]<=3));
+        (1<=pInfo->formatVersion[0] && pInfo->formatVersion[0]<=3);
 }
 
 /* semi-public functions ---------------------------------------------------- */
diff --git a/icu4c/source/common/uset.cpp b/icu4c/source/common/uset.cpp
index 8712da8b07fe..29b8655ac965 100644
--- a/icu4c/source/common/uset.cpp
+++ b/icu4c/source/common/uset.cpp
@@ -496,7 +496,7 @@ uset_serializedContains(const USerializedSet* set, UChar32 c) {
         } else {
             hi += 1;
         }
-        return (UBool)(hi&1);
+        return hi&1;
     } else {
         /* find c in the supplementary part */
         uint16_t high=(uint16_t)(c>>16), low=(uint16_t)c;
@@ -521,7 +521,7 @@ uset_serializedContains(const USerializedSet* set, UChar32 c) {
             hi += 2;
         }
         /* count pairs of 16-bit units even per BMP and check if the number of pairs is odd */
-        return (UBool)(((hi+(base<<1))&2)!=0);
+        return ((hi+(base<<1))&2)!=0;
     }
 }
 
diff --git a/icu4c/source/common/usprep.cpp b/icu4c/source/common/usprep.cpp
index 82dd7a4ca0fd..477b8f2309db 100644
--- a/icu4c/source/common/usprep.cpp
+++ b/icu4c/source/common/usprep.cpp
@@ -126,8 +126,7 @@ compareEntries(const UHashTok p1, const UHashTok p2) {
     name2.pointer = b2->name;
     path1.pointer = b1->path;
     path2.pointer = b2->path;
-    return ((UBool)(uhash_compareChars(name1, name2) & 
-        uhash_compareChars(path1, path2)));
+    return uhash_compareChars(name1, name2) & uhash_compareChars(path1, path2);
 }
 
 static void 
diff --git a/icu4c/source/common/ustr_wcs.cpp b/icu4c/source/common/ustr_wcs.cpp
index efbbbc2f1878..8ce0855226d6 100644
--- a/icu4c/source/common/ustr_wcs.cpp
+++ b/icu4c/source/common/ustr_wcs.cpp
@@ -57,7 +57,7 @@ u_growAnyBufferFromStatic(void *context,
     }
 
     *pBuffer=newBuffer;
-    return (UBool)(newBuffer!=nullptr);
+    return newBuffer!=nullptr;
 }
 
 /* helper function */
diff --git a/icu4c/source/common/utrie.cpp b/icu4c/source/common/utrie.cpp
index 88c01a53d2df..c27f447eddad 100644
--- a/icu4c/source/common/utrie.cpp
+++ b/icu4c/source/common/utrie.cpp
@@ -40,7 +40,7 @@ equal_uint32(const uint32_t *s, const uint32_t *t, int32_t length) {
         ++t;
         --length;
     }
-    return static_cast<UBool>(length == 0);
+    return length == 0;
 }
 
 /* Building a trie ----------------------------------------------------------*/
diff --git a/icu4c/source/common/utrie2.cpp b/icu4c/source/common/utrie2.cpp
index f8ed7cfc70fe..35be698fbb5d 100644
--- a/icu4c/source/common/utrie2.cpp
+++ b/icu4c/source/common/utrie2.cpp
@@ -389,7 +389,7 @@ utrie2_close(UTrie2 *trie) {
 
 U_CAPI UBool U_EXPORT2
 utrie2_isFrozen(const UTrie2 *trie) {
-    return (UBool)(trie->newTrie==nullptr);
+    return trie->newTrie==nullptr;
 }
 
 U_CAPI int32_t U_EXPORT2
diff --git a/icu4c/source/common/utrie2_builder.cpp b/icu4c/source/common/utrie2_builder.cpp
index 92e9fd733c4f..4bd49c7adfa4 100644
--- a/icu4c/source/common/utrie2_builder.cpp
+++ b/icu4c/source/common/utrie2_builder.cpp
@@ -506,7 +506,7 @@ isInNullBlock(UNewTrie2 *trie, UChar32 c, UBool forLSCP) {
             ((c>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK);
     }
     block=trie->index2[i2];
-    return static_cast<UBool>(block == trie->dataNullOffset);
+    return block == trie->dataNullOffset;
 }
 
 static int32_t
@@ -603,7 +603,7 @@ releaseDataBlock(UNewTrie2 *trie, int32_t block) {
 
 static inline UBool
 isWritableBlock(UNewTrie2 *trie, int32_t block) {
-    return static_cast<UBool>(block != trie->dataNullOffset && 1 == trie->map[block >> UTRIE2_SHIFT_2]);
+    return block != trie->dataNullOffset && 1 == trie->map[block >> UTRIE2_SHIFT_2];
 }
 
 static inline void
@@ -891,7 +891,7 @@ equal_int32(const int32_t *s, const int32_t *t, int32_t length) {
         ++t;
         --length;
     }
-    return static_cast<UBool>(length == 0);
+    return length == 0;
 }
 
 static inline UBool
@@ -901,7 +901,7 @@ equal_uint32(const uint32_t *s, const uint32_t *t, int32_t length) {
         ++t;
         --length;
     }
-    return static_cast<UBool>(length == 0);
+    return length == 0;
 }
 
 static int32_t
diff --git a/icu4c/source/i18n/calendar.cpp b/icu4c/source/i18n/calendar.cpp
index f74446b43765..96247174f70d 100644
--- a/icu4c/source/i18n/calendar.cpp
+++ b/icu4c/source/i18n/calendar.cpp
@@ -2849,7 +2849,7 @@ Calendar::inDaylightTime(UErrorCode& status) const
     // Force an update of the state of the Calendar.
     const_cast<Calendar*>(this)->complete(status); // cast away const
 
-    return static_cast<UBool>(U_SUCCESS(status) ? internalGet(UCAL_DST_OFFSET) != 0 : false);
+    return U_SUCCESS(status) ? internalGet(UCAL_DST_OFFSET) != 0 : false;
 }
 
 bool
diff --git a/icu4c/source/i18n/datefmt.cpp b/icu4c/source/i18n/datefmt.cpp
index 80f74ede65df..655cfbd1239d 100644
--- a/icu4c/source/i18n/datefmt.cpp
+++ b/icu4c/source/i18n/datefmt.cpp
@@ -763,7 +763,7 @@ DateFormat::setBooleanAttribute(UDateFormatBooleanAttribute attr,
 UBool 
 DateFormat::getBooleanAttribute(UDateFormatBooleanAttribute attr, UErrorCode &/*status*/) const {
 
-    return static_cast<UBool>(fBoolFlags.get(attr));
+    return fBoolFlags.get(attr);
 }
 
 U_NAMESPACE_END
diff --git a/icu4c/source/i18n/dtptngen.cpp b/icu4c/source/i18n/dtptngen.cpp
index 976e8d28b305..50c0b050b92e 100644
--- a/icu4c/source/i18n/dtptngen.cpp
+++ b/icu4c/source/i18n/dtptngen.cpp
@@ -1874,7 +1874,7 @@ DateTimePatternGenerator::setAvailableFormat(const UnicodeString &key, UErrorCod
 
 UBool
 DateTimePatternGenerator::isAvailableFormatSet(const UnicodeString &key) const {
-    return static_cast<UBool>(fAvailableFormatKeyHash->geti(key) == 1);
+    return fAvailableFormatKeyHash->geti(key) == 1;
 }
 
 void
@@ -2576,7 +2576,7 @@ FormatParser::getCanonicalIndex(const UnicodeString& s, UBool strict) {
 
 UBool
 FormatParser::isQuoteLiteral(const UnicodeString& s) {
-    return static_cast<UBool>(s.charAt(0) == SINGLE_QUOTE);
+    return s.charAt(0) == SINGLE_QUOTE;
 }
 
 // This function assumes the current itemIndex points to the quote literal.
diff --git a/icu4c/source/i18n/tznames_impl.h b/icu4c/source/i18n/tznames_impl.h
index eb4748799e2e..c628cd72edab 100644
--- a/icu4c/source/i18n/tznames_impl.h
+++ b/icu4c/source/i18n/tznames_impl.h
@@ -99,7 +99,7 @@ struct CharacterNode {
 };
 
 inline UBool CharacterNode::hasValues() const {
-    return static_cast<UBool>(fValues != nullptr);
+    return fValues != nullptr;
 }
 
 inline int32_t CharacterNode::countValues() const {
diff --git a/icu4c/source/i18n/unicode/tblcoll.h b/icu4c/source/i18n/unicode/tblcoll.h
index 3843691ddf5f..0c65e897f501 100644
--- a/icu4c/source/i18n/unicode/tblcoll.h
+++ b/icu4c/source/i18n/unicode/tblcoll.h
@@ -850,7 +850,7 @@ class U_I18N_API RuleBasedCollator final : public Collator {
     }
     UBool attributeHasBeenSetExplicitly(int32_t attribute) const {
         // assert(0 <= attribute < ATTR_LIMIT);
-        return static_cast<UBool>((explicitlySetAttributes & (static_cast<uint32_t>(1) << attribute)) != 0);
+        return (explicitlySetAttributes & (static_cast<uint32_t>(1) << attribute)) != 0;
     }
 
     /**
diff --git a/icu4c/source/io/ufmt_cmn.cpp b/icu4c/source/io/ufmt_cmn.cpp
index 0202783f8b5e..7930fe30beb6 100644
--- a/icu4c/source/io/ufmt_cmn.cpp
+++ b/icu4c/source/io/ufmt_cmn.cpp
@@ -58,7 +58,7 @@ ufmt_isdigit(char16_t  c,
 {
     int digitVal = ufmt_digitvalue(c);
 
-    return static_cast<UBool>(digitVal < radix && digitVal >= 0);
+    return digitVal < radix && digitVal >= 0;
 }
 
 #define TO_UC_DIGIT(a) a <= 9 ? (DIGIT_0 + a) : (0x0037 + a)
diff --git a/icu4c/source/test/cintltst/chashtst.c b/icu4c/source/test/cintltst/chashtst.c
index a4b774d93a1c..729b9b9c3ae0 100644
--- a/icu4c/source/test/cintltst/chashtst.c
+++ b/icu4c/source/test/cintltst/chashtst.c
@@ -379,9 +379,9 @@ static int32_t U_EXPORT2 U_CALLCONV hashChars(const UHashTok key) {
 }
 
 static UBool U_EXPORT2 U_CALLCONV isEqualChars(const UHashTok key1, const UHashTok key2) {
-    return (UBool)((key1.pointer != NULL) &&
-        (key2.pointer != NULL) &&
-        (uprv_strcmp((const char*)key1.pointer, (const char*)key2.pointer) == 0));
+    return key1.pointer != NULL &&
+           key2.pointer != NULL &&
+           uprv_strcmp((const char*)key1.pointer, (const char*)key2.pointer) == 0;
 }
 
 /**********************************************************************
diff --git a/icu4c/source/test/cintltst/cintltst.c b/icu4c/source/test/cintltst/cintltst.c
index 4c6d5fc6dec7..5af75680138a 100644
--- a/icu4c/source/test/cintltst/cintltst.c
+++ b/icu4c/source/test/cintltst/cintltst.c
@@ -723,7 +723,7 @@ U_CFUNC UBool assertTrue(const char* msg, int /*not UBool*/ condition) {
         log_verbose("Ok: %s\n", msg);
     }
 #endif
-    return (UBool)condition;   
+    return condition;
 }
 
 U_CFUNC UBool assertEquals(const char* message, const char* expected,
diff --git a/icu4c/source/test/cintltst/crestst.c b/icu4c/source/test/cintltst/crestst.c
index 7d0476462e66..f32dce366eac 100644
--- a/icu4c/source/test/cintltst/crestst.c
+++ b/icu4c/source/test/cintltst/crestst.c
@@ -428,7 +428,7 @@ UBool testTag(const char* frag,
         ures_close(theBundle);
     }
     free(base);
-    return (UBool)(passNum == pass);
+    return passNum == pass;
 }
 
 void record_pass(void)
diff --git a/icu4c/source/test/cintltst/creststn.c b/icu4c/source/test/cintltst/creststn.c
index 4877d8b49ccf..d5b0bb4febf8 100644
--- a/icu4c/source/test/cintltst/creststn.c
+++ b/icu4c/source/test/cintltst/creststn.c
@@ -2055,7 +2055,7 @@ static UBool testTag(const char* frag,
     ures_close(tags);
     ures_close(arrayItem1);
     free(base);
-    return (UBool)(failNum == fail);
+    return failNum == fail;
 }
 
 static void record_pass(void)
diff --git a/icu4c/source/test/intltest/nptrans.cpp b/icu4c/source/test/intltest/nptrans.cpp
index aebf18104924..879fdfa16af3 100644
--- a/icu4c/source/test/intltest/nptrans.cpp
+++ b/icu4c/source/test/intltest/nptrans.cpp
@@ -122,7 +122,7 @@ NamePrepTransform::NamePrepTransform(UParseError& parseError, UErrorCode& status
 
 
 UBool NamePrepTransform::isProhibited(UChar32 ch){ 
-    return static_cast<UBool>(ch != ASCII_SPACE);
+    return ch != ASCII_SPACE;
 }
 
 NamePrepTransform::~NamePrepTransform(){
diff --git a/icu4c/source/test/intltest/restest.cpp b/icu4c/source/test/intltest/restest.cpp
index 381dfa25627a..661312ad5316 100644
--- a/icu4c/source/test/intltest/restest.cpp
+++ b/icu4c/source/test/intltest/restest.cpp
@@ -499,12 +499,12 @@ ResourceBundleTest::testTag(const char* frag,
         else if (status != expected_resource_status)
         {
             record_fail("Error getting " + UnicodeString(tag));
-            return static_cast<UBool>(failOrig != fail);
+            return failOrig != fail;
         }
 
     }
 
-    return static_cast<UBool>(failOrig != fail);
+    return failOrig != fail;
 }
 
 void
diff --git a/icu4c/source/test/intltest/restsnew.cpp b/icu4c/source/test/intltest/restsnew.cpp
index 1bdfa2140781..a7bbf7717d9b 100644
--- a/icu4c/source/test/intltest/restsnew.cpp
+++ b/icu4c/source/test/intltest/restsnew.cpp
@@ -1051,7 +1051,7 @@ NewResourceBundleTest::testTag(const char* frag,
         CONFIRM_EQ(count, tag_count);
 
     }
-    return static_cast<UBool>(failOrig == fail);
+    return failOrig == fail;
 }
 
 void
diff --git a/icu4c/source/test/intltest/usettest.cpp b/icu4c/source/test/intltest/usettest.cpp
index 18320f928fd7..b047b01bfa2d 100644
--- a/icu4c/source/test/intltest/usettest.cpp
+++ b/icu4c/source/test/intltest/usettest.cpp
@@ -2530,7 +2530,7 @@ class UnicodeSetWithStrings {
     }
 
     UBool hasStrings() const {
-        return static_cast<UBool>(stringsLength > 0);
+        return stringsLength > 0;
     }
 
     UBool hasStringsWithSurrogates() const {
diff --git a/icu4c/source/test/perf/unisetperf/draft/bitset.cpp b/icu4c/source/test/perf/unisetperf/draft/bitset.cpp
index dc72cf4df237..d720b3827e4b 100644
--- a/icu4c/source/test/perf/unisetperf/draft/bitset.cpp
+++ b/icu4c/source/test/perf/unisetperf/draft/bitset.cpp
@@ -190,9 +190,9 @@ class BitSet : public UObject, public UnicodeContainable {
 
     UBool contains(UChar32 c) const override {
         if (static_cast<uint32_t>(c) <= 0xff) {
-            return static_cast<UBool>((latin1Set[c >> 5] & (static_cast<uint32_t>(1) << (c & 0x1f))) != 0);
+            return (latin1Set[c >> 5] & (static_cast<uint32_t>(1) << (c & 0x1f))) != 0;
         } else if (static_cast<uint32_t>(c) < 0xffff) {
-            return static_cast<UBool>((bits[c >> 6] & (INT64_C(1) << (c & 0x3f))) != 0);
+            return (bits[c >> 6] & (INT64_C(1) << (c & 0x3f))) != 0;
         } else {
             return restSet->contains(c);
         }
diff --git a/icu4c/source/test/perf/unisetperf/draft/trieset.cpp b/icu4c/source/test/perf/unisetperf/draft/trieset.cpp
index 9c15179216c1..d5406601fcef 100644
--- a/icu4c/source/test/perf/unisetperf/draft/trieset.cpp
+++ b/icu4c/source/test/perf/unisetperf/draft/trieset.cpp
@@ -108,9 +108,9 @@ class TrieSet : public UObject, public UnicodeContainable {
 
     UBool contains(UChar32 c) const override {
         if (static_cast<uint32_t>(c) <= 0xff) {
-            return static_cast<UBool>(latin1[c]);
+            return latin1[c];
         } else if (static_cast<uint32_t>(c) < 0xffff) {
-            return static_cast<UBool>(UTRIE_GET8_FROM_LEAD(&trie, c));
+            return UTRIE_GET8_FROM_LEAD(&trie, c);
         } else {
             return restSet->contains(c);
         }
diff --git a/icu4c/source/tools/genrb/parse.cpp b/icu4c/source/tools/genrb/parse.cpp
index f0bf9e79a0b4..f487241cc189 100644
--- a/icu4c/source/tools/genrb/parse.cpp
+++ b/icu4c/source/tools/genrb/parse.cpp
@@ -2137,7 +2137,7 @@ void initParser()
 }
 
 static inline UBool isTable(enum EResourceType type) {
-    return static_cast<UBool>(type == RESTYPE_TABLE || type == RESTYPE_TABLE_NO_FALLBACK);
+    return type == RESTYPE_TABLE || type == RESTYPE_TABLE_NO_FALLBACK;
 }
 
 static enum EResourceType
diff --git a/icu4c/source/tools/gensprep/store.c b/icu4c/source/tools/gensprep/store.c
index f0f4d7844be8..b2cf44d186b3 100644
--- a/icu4c/source/tools/gensprep/store.c
+++ b/icu4c/source/tools/gensprep/store.c
@@ -233,7 +233,7 @@ static int32_t U_CALLCONV hashEntry(const UHashTok parm) {
 
 /* Callback for comparing two entries */
 static UBool U_CALLCONV compareEntries(const UHashTok p1, const UHashTok p2) {
-    return (UBool)(p1.integer != p2.integer);
+    return p1.integer != p2.integer;
 }
 
 
diff --git a/icu4c/source/tools/icupkg/icupkg.cpp b/icu4c/source/tools/icupkg/icupkg.cpp
index 45663d413ac4..3da4af745786 100644
--- a/icu4c/source/tools/icupkg/icupkg.cpp
+++ b/icu4c/source/tools/icupkg/icupkg.cpp
@@ -253,7 +253,7 @@ isPackageName(const char *filename) {
     int32_t len;
 
     len = static_cast<int32_t>(strlen(filename)) - 4; /* -4: subtract the length of ".dat" */
-    return static_cast<UBool>(len > 0 && 0 == strcmp(filename + len, ".dat"));
+    return len > 0 && 0 == strcmp(filename + len, ".dat");
 }
 /*
 This line is required by MinGW because it incorrectly globs the arguments.
diff --git a/icu4c/source/tools/makeconv/genmbcs.cpp b/icu4c/source/tools/makeconv/genmbcs.cpp
index 774cdc6045d1..25b5ddcb0152 100644
--- a/icu4c/source/tools/makeconv/genmbcs.cpp
+++ b/icu4c/source/tools/makeconv/genmbcs.cpp
@@ -559,7 +559,7 @@ MBCSIsValid(NewConverter *cnvData,
             const uint8_t *bytes, int32_t length) {
     MBCSData *mbcsData=(MBCSData *)cnvData;
 
-    return (UBool)(1==ucm_countChars(&mbcsData->ucm->states, bytes, length));
+    return 1==ucm_countChars(&mbcsData->ucm->states, bytes, length);
 }
 U_CDECL_END
 static UBool
diff --git a/icu4c/source/tools/toolutil/package.cpp b/icu4c/source/tools/toolutil/package.cpp
index dd4814927833..e58c6648b647 100644
--- a/icu4c/source/tools/toolutil/package.cpp
+++ b/icu4c/source/tools/toolutil/package.cpp
@@ -1233,7 +1233,7 @@ UBool
 Package::checkDependencies() {
     isMissingItems=false;
     enumDependencies(this, checkDependency);
-    return static_cast<UBool>(!isMissingItems);
+    return !isMissingItems;
 }
 
 void