Add Windows ARM64 support

Currently we do not have fcontext related ASM files for Windows ARM64.
So we can use winfib context-impl only for Windows ARM64.

Fixes issue : https://github.com/boostorg/boost/issues/1070
Related to PR: https://github.com/boostorg/boost/pull/1077

.github/workflows/ci.yml

@@ -54,7 +54,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ windows-2022, windows-2025 ]
+        os: [ windows-2022, windows-2025, windows-11-arm ]
 
     runs-on: ${{matrix.os}}
 

build/Jamfile.v2

@@ -18,6 +18,7 @@ import config : requires ;
 project
     : common-requirements <library>$(boost_dependencies)
     : requirements
+      <target-os>windows,<architecture>arm,<address-model>64:<context-impl>winfib
       <target-os>windows:<define>_WIN32_WINNT=0x0601
       <target-os>linux,<toolset>gcc,<segmented-stacks>on:<cxxflags>-fsplit-stack
       <target-os>linux,<toolset>gcc,<segmented-stacks>on:<cxxflags>-DBOOST_USE_SEGMENTED_STACKS
@@ -189,15 +190,12 @@ alias asm_sources
      <toolset>gcc
    ;
 
-# ARM64/AAPCS/PE — also allow <abi>ms for Windows on ARM64 (MSVC)
+# ARM64/AAPCS/PE
-# <abi>ms only applies when
-# <architecture>arm <address-model>64 <binary-format>pe,
-# so x86/x64 MSVC builds are unaffected.
 alias asm_sources
    : asm/make_arm64_aapcs_pe_armasm.asm
      asm/jump_arm64_aapcs_pe_armasm.asm
      asm/ontop_arm64_aapcs_pe_armasm.asm
-   : <abi>aapcs,<abi>ms
+   : <abi>aapcs
      <address-model>64
      <architecture>arm
      <binary-format>pe

test/Jamfile.v2

@@ -41,6 +41,10 @@ rule native-impl ( properties * )
     {
         result = <build>no ;
     }
+    else if ( <target-os>windows in $(properties) && <architecture>arm in $(properties) && <address-model>64 in $(properties) )
+    {
+        return <context-impl>winfib ;   # for windows arm64 always use winfib and skip ASM
+    }
     else if ( ! ( <target-os>windows in $(properties) ) )
     {
         result = <context-impl>ucontext ;
@@ -52,6 +56,22 @@ rule native-impl ( properties * )
     return $(result) ;
 }
 
+rule fcontext-impl ( properties * )
+{
+    # Skip on Windows ARM64
+    if ( <target-os>windows in $(properties) &&
+         <architecture>arm in $(properties) &&
+         <address-model>64 in $(properties) )
+    {
+        return <build>no ; # for windows arm64 always use winfib and skip fcontext
+    }
+    else
+    {
+        return <context-impl>fcontext ;
+    }
+}
+
+
 obj is_libstdcxx : is_libstdcxx.cpp ;
 explicit is_libstdcxx ;
 
@@ -95,7 +115,7 @@ test-suite minimal :
 
 [ run test_fiber.cpp :
     : :
-    <context-impl>fcontext
+    <conditional>@fcontext-impl
     [ requires cxx11_auto_declarations
                cxx11_constexpr
                cxx11_defaulted_functions
@@ -150,7 +170,7 @@ test-suite minimal :
 
 [ run test_callcc.cpp :
     : :
-    <context-impl>fcontext
+     <conditional>@fcontext-impl
     [ requires cxx11_auto_declarations
                cxx11_constexpr
                cxx11_defaulted_functions