fix: normalize Unicode minus sign in GSP number formatting for locale compatibility

grails-fields/grails-app/taglib/grails/plugin/formfields/FormFieldsTagLib.groovy

@@ -19,6 +19,8 @@
 package grails.plugin.formfields
 
 import java.sql.Blob
+import java.text.DecimalFormat
+import java.text.DecimalFormatSymbols
 import java.text.NumberFormat
 import java.time.Instant
 import java.time.LocalDate
@@ -833,7 +835,15 @@ class FormFieldsTagLib {
 
     @CompileStatic
     protected NumberFormat getNumberFormatter() {
-        NumberFormat.getInstance(getLocale())
+        NumberFormat numberFormat = NumberFormat.getInstance(getLocale())
+        // Normalize Unicode minus sign (U+2212) to ASCII hyphen-minus (U+002D)
+        // for HTML compatibility (fixes grails-core#15178)
+        if (numberFormat instanceof DecimalFormat) {
+            DecimalFormatSymbols symbols = ((DecimalFormat) numberFormat).decimalFormatSymbols
+            symbols.minusSign = '-' as char
+            ((DecimalFormat) numberFormat).decimalFormatSymbols = symbols
+        }
+        return numberFormat
     }
 
     @CompileStatic

grails-gsp/plugin/src/main/groovy/org/grails/plugins/web/taglib/FormatTagLib.groovy

@@ -327,13 +327,25 @@ class FormatTagLib implements TagLibrary {
             number = decimalFormat.parse(number as String)
         }
 
+        // Normalize Unicode minus sign (U+2212) to ASCII hyphen-minus (U+002D)
+        // for HTML compatibility (fixes grails-core#15178)
+        DecimalFormatSymbols formatSymbols = decimalFormat.decimalFormatSymbols
+        formatSymbols.minusSign = '-' as char
+        decimalFormat.decimalFormatSymbols = formatSymbols
+
         def formatted
         try {
             formatted = decimalFormat.format(number)
         }
         catch (ArithmeticException e) {
             // if roundingMode is UNNECESSARY and ArithemeticException raises, just return original number formatted with default number formatting
-            formatted = NumberFormat.getNumberInstance(locale).format(number)
+            NumberFormat fallbackFormat = NumberFormat.getNumberInstance(locale)
+            if (fallbackFormat instanceof DecimalFormat) {
+                DecimalFormatSymbols fallbackSymbols = ((DecimalFormat) fallbackFormat).decimalFormatSymbols
+                fallbackSymbols.minusSign = '-' as char
+                ((DecimalFormat) fallbackFormat).decimalFormatSymbols = fallbackSymbols
+            }
+            formatted = fallbackFormat.format(number)
         }
         return formatted
     }

grails-gsp/plugin/src/main/groovy/org/grails/plugins/web/taglib/ValidationTagLib.groovy

@@ -471,7 +471,12 @@ class ValidationTagLib implements TagLibrary {
         PropertyEditor editor = registry.findCustomEditor(value.getClass(), propertyPath)
         if (editor) {
             editor.setValue(value)
-            return !(value instanceof Number) ? editor.asText?.encodeAsHTML() : editor.asText
+            String formattedValue = editor.asText
+            if (value instanceof Number && formattedValue != null) {
+                DecimalFormatSymbols formatSymbols = new DecimalFormatSymbols(webRequest.getLocale())
+                formattedValue = formattedValue.replace(formatSymbols.minusSign, '-' as char)
+            }
+            return !(value instanceof Number) ? formattedValue?.encodeAsHTML() : formattedValue
         }
 
         if (value instanceof Number) {
@@ -482,6 +487,7 @@ class ValidationTagLib implements TagLibrary {
 
             def locale = webRequest.getLocale()
             def dcfs = locale ? new DecimalFormatSymbols(locale) : new DecimalFormatSymbols()
+            dcfs.minusSign = '-' as char
             def decimalFormat = new DecimalFormat(pattern, dcfs)
             value = decimalFormat.format(value)
         }

grails-gsp/plugin/src/test/groovy/org/grails/web/taglib/FormatTagLibSpec.groovy

@@ -21,6 +21,7 @@ package org.grails.web.taglib
 import grails.testing.web.taglib.TagLibUnitTest
 import org.grails.plugins.web.taglib.FormatTagLib
 import spock.lang.IgnoreIf
+import spock.lang.Issue
 import spock.lang.Requires
 import spock.lang.Specification
 
@@ -57,4 +58,14 @@ class FormatTagLibSpec extends Specification implements TagLibUnitTest<FormatTag
         expect:
         "3,12${new String([160] as char[])}\$" == applyTemplate('<g:formatNumber type="currency" currencyCode="USD" number="${number}" locale="fi_FI" />',  [number: number])
     }
+
+    @Issue('https://github.com/apache/grails-core/issues/15178')
+    void "formatNumber uses ASCII minus sign for negative numbers with Norwegian locale"() {
+        when:
+        def result = applyTemplate('<g:formatNumber number="${n}" type="number" locale="nb_NO"/>', [n: -42])
+
+        then: "ASCII minus (U+002D) is used, not Unicode minus (U+2212)"
+        result.contains('-')
+        !result.contains('\u2212')
+    }
 }

grails-gsp/plugin/src/test/groovy/org/grails/web/taglib/FormatTagLibTests.groovy

@@ -331,4 +331,32 @@ class FormatTagLibTests extends AbstractGrailsTagTests {
         def template = '<g:formatNumber number="${number}" nan="n/a"/>'
         assertOutputEquals("n/a", template, [number: number])
     }
+
+    @Issue('https://github.com/apache/grails-core/issues/15178')
+    @Test
+    void testFormatNumberNegativeWithNorwegianLocale() {
+        def template = '<g:formatNumber number="${myNumber}" type="number" locale="nb_NO"/>'
+        def result = applyTemplate(template, [myNumber: -42])
+        // Verify ASCII minus (U+002D) is used, not Unicode minus (U+2212)
+        assert result.charAt(0) == '-' as char
+        assert !result.contains('\u2212')
+    }
+
+    @Issue('https://github.com/apache/grails-core/issues/15178')
+    @Test
+    void testFormatNumberNegativeLongWithNorwegianLocale() {
+        def template = '<g:formatNumber number="${myNumber}" format="0" locale="nb_NO"/>'
+        def result = applyTemplate(template, [myNumber: -123456L])
+        assert result.contains('-')
+        assert !result.contains('\u2212')
+    }
+
+    @Issue('https://github.com/apache/grails-core/issues/15178')
+    @Test
+    void testFormatNumberNegativeBigDecimalWithNorwegianLocale() {
+        def template = '<g:formatNumber number="${myNumber}" format="0.00" locale="nb_NO"/>'
+        def result = applyTemplate(template, [myNumber: new BigDecimal("-99.95")])
+        assert result.contains('-')
+        assert !result.contains('\u2212')
+    }
 }

grails-gsp/plugin/src/test/groovy/org/grails/web/taglib/ValidationTagLibSpec.groovy

@@ -31,6 +31,7 @@ import org.springframework.beans.factory.support.RootBeanDefinition
 import org.springframework.context.MessageSourceResolvable
 import org.springframework.context.i18n.LocaleContextHolder
 import org.springframework.validation.FieldError
+import spock.lang.Issue
 import spock.lang.PendingFeature
 import spock.lang.Specification
 
@@ -259,6 +260,22 @@ class ValidationTagLibSpec extends Specification implements TagLibUnitTest<Valid
         applyTemplate(template, [book:b]) == "1.045,456"
     }
 
+    @Issue('https://github.com/apache/grails-core/issues/15178')
+    void testFieldValueTagWithNorwegianLocaleUsesAsciiMinus() {
+        given:
+        def b = new ValidationTagLibBook()
+        b.usPrice = -42.5
+        def template = '<g:fieldValue bean="${book}" field="usPrice" />'
+
+        when:
+        webRequest.currentRequest.addPreferredLocale(new Locale('nb', 'NO'))
+        def result = applyTemplate(template, [book: b])
+
+        then:
+        result.contains('-')
+        !result.contains('\u2212')
+    }
+
     @PendingFeature // Was valid for JVM lower than 14 because space is converted to narrow no-break space 8239 and is not encoded
     void testFieldValueTagWithFrenchLocaleInTextField() {
         given:

grails-test-examples/gsp-layout/grails-app/controllers/org/example/grails/layout/TagLibController.groovy

@@ -57,6 +57,14 @@ class TagLibController {
         ]
     }
 
+    def formatLocaleNumber() {
+        [
+            negativeInt: -42,
+            negativeLong: -123456789L,
+            negativeBigDecimal: new BigDecimal('-99999.99')
+        ]
+    }
+
     def setTag() {
         render(view: 'setTag')
     }

grails-test-examples/gsp-layout/grails-app/views/tagLib/formatLocaleNumber.gsp

@@ -0,0 +1,31 @@
+<%--
+  ~  Licensed to the Apache Software Foundation (ASF) under one
+  ~  or more contributor license agreements.  See the NOTICE file
+  ~  distributed with this work for additional information
+  ~  regarding copyright ownership.  The ASF licenses this file
+  ~  to you under the Apache License, Version 2.0 (the
+  ~  "License"); you may not use this file except in compliance
+  ~  with the License.  You may obtain a copy of the License at
+  ~
+  ~    https://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~  Unless required by applicable law or agreed to in writing,
+  ~  software distributed under the License is distributed on an
+  ~  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  ~  KIND, either express or implied.  See the License for the
+  ~  specific language governing permissions and limitations
+  ~  under the License.
+  --%>
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Format Locale Number Test</title>
+</head>
+<body>
+    <h1>Format Locale Number Test</h1>
+    <span id="neg-int-no"><g:formatNumber number="${negativeInt}" locale="nb_NO"/></span>
+    <span id="neg-long-no"><g:formatNumber number="${negativeLong}" locale="nb_NO" format="#,##0"/></span>
+    <span id="neg-decimal-no"><g:formatNumber number="${negativeBigDecimal}" locale="nb_NO" format="#,##0.00"/></span>
+    <span id="pos-number-no"><g:formatNumber number="${42}" locale="nb_NO"/></span>
+</body>
+</html>

grails-test-examples/gsp-layout/src/integration-test/groovy/GspTagLibSpec.groovy

@@ -184,6 +184,44 @@ class GspTagLibSpec extends ContainerGebSpec {
         $('#boolean-display').text().contains('Yes')
     }
 
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative int"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-int-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative long"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-long-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative BigDecimal"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-decimal-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale formats positive numbers correctly"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        $('#pos-number-no').text() == '42'
+    }
+
     def "g:set creates local variable"() {
         when:
         go('tagLib/setTag')
@@ -272,4 +310,42 @@ class GspTagLibSpec extends ContainerGebSpec {
         $('#url-encoded').text().contains('%3D') ||  // encoded =
         $('#url-encoded').text().contains('param')   // at least the content is there
     }
+
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative int"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-int-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative long"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-long-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale uses ASCII minus for negative BigDecimal"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        def text = $('#neg-decimal-no').text()
+        text.contains('-')
+        !text.contains('\u2212')
+    }
+
+    def "g:formatNumber with Norwegian locale formats positive numbers correctly"() {
+        when:
+        go('tagLib/formatLocaleNumber')
+
+        then:
+        $('#pos-number-no').text() == '42'
+    }
 }