Source: Add and use CM_UNREACHABLE macro

In debug builds, we assert and abort to give more useful crashes for
development (i.e., instead of triggering UB). Otherwise, we get the
optimization benefits of `unreachable()` (or the older
platform-specific fallbacks per `cm/utility`).

Source/cmCMakePresetsGraphResolve.cxx

@@ -1,6 +1,5 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file LICENSE.rst or https://cmake.org/licensing for details.  */
-#include <cassert>
 #include <map>
 #include <string>
 
@@ -8,6 +7,7 @@
 
 #include "cmCMakePresetsGraph.h"
 #include "cmStringAlgorithms.h"
+#include "cmUnreachable.h"
 
 template <class T>
 cmCMakePresetsGraph::PresetResolveResult<T> cmCMakePresetsGraph::ResolvePreset(
@@ -94,7 +94,7 @@ cm::optional<std::string> cmCMakePresetsGraph::FormatPresetError(
     case Status::Success:
       return cm::nullopt;
   }
-  assert(false && "Unreachable.");
+  CM_UNREACHABLE;
   return cm::nullopt;
 }
 

Source/cmCryptoHash.cxx

@@ -2,8 +2,6 @@
    file LICENSE.rst or https://cmake.org/licensing for details.  */
 #include "cmCryptoHash.h"
 
-#include <cassert>
-
 #include <cm/memory>
 
 #include <cm3p/kwiml/int.h>
@@ -11,6 +9,8 @@
 
 #include "cmsys/FStream.hxx"
 
+#include "cmUnreachable.h"
+
 static unsigned int const cmCryptoHashAlgoToId[] = {
   /* clang-format needs this comment to break after the opening brace */
   RHASH_MD5,      //
@@ -109,7 +109,7 @@ std::string cmCryptoHash::GetHashAlgoName() const
     case RHASH_SHA3_512:
       return "SHA3_512";
   }
-  assert(false);
+  CM_UNREACHABLE;
   return "UNKNOWN";
 }
 

Source/cmCxxModuleMapper.cxx

@@ -2,7 +2,6 @@
    file LICENSE.rst or https://cmake.org/licensing for details.  */
 #include "cmCxxModuleMapper.h"
 
-#include <cassert>
 #include <cstddef>
 #include <set>
 #include <sstream>
@@ -16,6 +15,7 @@
 #include "cmScanDepFormat.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
+#include "cmUnreachable.h"
 
 CxxBmiLocation::CxxBmiLocation() = default;
 
@@ -216,7 +216,7 @@ std::string CxxModuleMapContentMsvc(CxxModuleLocations const& loc,
       case LookupMethod::IncludeQuote:
         return "-headerUnit:quote"_s;
     }
-    assert(false && "unsupported lookup method");
+    CM_UNREACHABLE;
     return ""_s;
   };
 
@@ -265,7 +265,7 @@ bool CxxModuleUsage::AddReference(std::string const& logical,
         case LookupMethod::IncludeQuote:
           return "include-quote"_s;
       }
-      assert(false && "unsupported lookup method");
+      CM_UNREACHABLE;
       return ""_s;
     };
 
@@ -432,7 +432,7 @@ std::string CxxModuleMapContent(CxxModuleMapFormat format,
       return CxxModuleMapContentMsvc(loc, obj, usages);
   }
 
-  assert(false);
+  CM_UNREACHABLE;
   return {};
 }
 
@@ -446,6 +446,6 @@ CxxModuleMapMode CxxModuleMapOpenMode(CxxModuleMapFormat format)
       return CxxModuleMapMode::Default;
   }
 
-  assert(false);
+  CM_UNREACHABLE;
   return CxxModuleMapMode::Default;
 }

Source/cmFileAPI.cxx

@@ -29,6 +29,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTimestamp.h"
+#include "cmUnreachable.h"
 #include "cmake.h"
 
 #if defined(__clang__) && defined(__has_warning)
@@ -835,7 +836,7 @@ Json::Value cmFileAPI::BuildCodeModel(Object object)
   if (object.Version == 2) {
     version = BuildVersion(2, CodeModelV2Minor);
   } else {
-    return codemodel; // should be unreachable
+    CM_UNREACHABLE;
   }
 
   return codemodel;
@@ -870,7 +871,7 @@ Json::Value cmFileAPI::BuildConfigureLog(Object object)
   if (object.Version == 1) {
     version = BuildVersion(1, ConfigureLogV1Minor);
   } else {
-    return configureLog; // should be unreachable
+    CM_UNREACHABLE;
   }
 
   return configureLog;
@@ -904,7 +905,7 @@ Json::Value cmFileAPI::BuildCache(Object object)
   if (object.Version == 2) {
     version = BuildVersion(2, CacheV2Minor);
   } else {
-    return cache; // should be unreachable
+    CM_UNREACHABLE;
   }
 
   return cache;
@@ -938,7 +939,7 @@ Json::Value cmFileAPI::BuildCMakeFiles(Object object)
   if (object.Version == 1) {
     version = BuildVersion(1, CMakeFilesV1Minor);
   } else {
-    return cmakeFiles; // should be unreachable
+    CM_UNREACHABLE;
   }
 
   return cmakeFiles;
@@ -972,7 +973,7 @@ Json::Value cmFileAPI::BuildToolchains(Object object)
   if (object.Version == 1) {
     version = BuildVersion(1, ToolchainsV1Minor);
   } else {
-    return toolchains; // should be unreachable
+    CM_UNREACHABLE;
   }
 
   return toolchains;

Source/cmFindPackageCommand.cxx

@@ -43,6 +43,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmVersionMacros.h"
 #include "cmWindowsRegistry.h"
@@ -3668,7 +3669,7 @@ void cmFindPackageDebugState::WriteEvent(cmConfigureLog& log,
         case pdt::Cps:
           return "cps";
       }
-      assert(false);
+      CM_UNREACHABLE;
       return "<UNKNOWN>";
     };
 
@@ -3712,7 +3713,7 @@ void cmFindPackageDebugState::WriteEvent(cmConfigureLog& log,
         case cmFindPackageCommand::RequiredStatus::RequiredFromFindVar:
           return "required_from_find_variable";
       }
-      assert(false);
+      CM_UNREACHABLE;
       return "<UNKNOWN>";
     };
     log.BeginObject("settings"_s);
@@ -3749,7 +3750,7 @@ void cmFindPackageDebugState::WriteEvent(cmConfigureLog& log,
           case cmFindCommon::RootPathModeBoth:
             return "BOTH";
         }
-        assert(false);
+        CM_UNREACHABLE;
         return "<UNKNOWN>";
       };
       log.BeginObject("paths"_s);
@@ -3789,7 +3790,7 @@ void cmFindPackageDebugState::WriteEvent(cmConfigureLog& log,
       case cmFindPackageCommand::FoundPackageMode::Provider:
         return "provider";
     }
-    assert(false);
+    CM_UNREACHABLE;
     return "<UNKNOWN>";
   };
   if (!fpc->ConsideredPaths.empty()) {
@@ -3813,7 +3814,7 @@ void cmFindPackageDebugState::WriteEvent(cmConfigureLog& log,
         case cmFindPackageCommand::SearchResult::NotFound:
           return "not_found";
       }
-      assert(false);
+      CM_UNREACHABLE;
       return "<UNKNOWN>";
     };
 

Source/cmGeneratorExpression.cxx

@@ -3,7 +3,6 @@
 #include "cmGeneratorExpression.h"
 
 #include <algorithm>
-#include <cassert>
 #include <cstddef>
 #include <memory>
 #include <stack>
@@ -26,6 +25,7 @@
 #include "cmMessageType.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
+#include "cmUnreachable.h"
 #include "cmake.h"
 
 cmGeneratorExpression::cmGeneratorExpression(cmake& cmakeInstance,
@@ -283,7 +283,7 @@ static std::string stripExportInterface(
       foundGenex = FoundGenex::BuildLocalInterface;
       pos += cmStrLen("$<BUILD_LOCAL_INTERFACE:");
     } else {
-      assert(false && "Invalid position found");
+      CM_UNREACHABLE;
     }
     nestingLevel = 1;
     char const* c = input.data() + pos;
@@ -406,8 +406,7 @@ std::string cmGeneratorExpression::Preprocess(cm::string_view input,
     return stripExportInterface(input, context, importPrefix);
   }
 
-  assert(false &&
-         "cmGeneratorExpression::Preprocess called with invalid args");
+  CM_UNREACHABLE;
   return std::string();
 }
 

Source/cmGeneratorExpressionNode.cxx

@@ -55,6 +55,7 @@
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmake.h"
 
@@ -3388,8 +3389,7 @@ static const struct ConfigurationTestNode : public cmGeneratorExpressionNode
               return false;
           }
 
-          // Should be unreachable
-          assert(false);
+          CM_UNREACHABLE;
           return false;
         }();
 
@@ -5140,7 +5140,7 @@ static cmPolicies::PolicyStatus statusForTarget(cmGeneratorTarget const* tgt,
 
 #undef RETURN_POLICY
 
-  assert(false && "Unreachable code. Not a valid policy");
+  CM_UNREACHABLE;
   return cmPolicies::WARN;
 }
 
@@ -5155,7 +5155,7 @@ static cmPolicies::PolicyID policyForString(char const* policy_id)
 
 #undef RETURN_POLICY_ID
 
-  assert(false && "Unreachable code. Not a valid policy");
+  CM_UNREACHABLE;
   return cmPolicies::CMPCOUNT;
 }
 

Source/cmGeneratorExpressionParser.cxx

@@ -11,6 +11,7 @@
 #include <cmext/memory>
 
 #include "cmGeneratorExpressionEvaluator.h"
+#include "cmUnreachable.h"
 
 cmGeneratorExpressionParser::cmGeneratorExpressionParser(
   std::vector<cmGeneratorExpressionToken> tokens)
@@ -234,11 +235,11 @@ void cmGeneratorExpressionParser::ParseContent(
       if (this->NestingLevel == 0) {
         extendText(result, this->it);
       } else {
-        assert(false && "Got unexpected syntax token.");
+        CM_UNREACHABLE;
       }
       assert(this->it != this->Tokens.end());
       ++this->it;
       return;
   }
-  assert(false && "Unhandled token in generator expression.");
+  CM_UNREACHABLE;
 }

Source/cmGeneratorTarget_CompatibleInterface.cxx

@@ -30,6 +30,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 
 namespace {
@@ -136,8 +137,7 @@ char const* getLinkInterfaceDependentProperty(cmGeneratorTarget const* tgt,
 {
   switch (t) {
     case BoolType:
-      assert(false &&
-             "String compatibility check function called for boolean");
+      CM_UNREACHABLE;
       return nullptr;
     case StringType:
       return tgt->GetLinkInterfaceDependentStringProperty(prop, config);
@@ -146,7 +146,7 @@ char const* getLinkInterfaceDependentProperty(cmGeneratorTarget const* tgt,
     case NumberMaxType:
       return tgt->GetLinkInterfaceDependentNumberMaxProperty(prop, config);
   }
-  assert(false && "Unreachable!");
+  CM_UNREACHABLE;
   return nullptr;
 }
 
@@ -367,7 +367,7 @@ static std::string compatibilityType(CompatibleType t)
     case NumberMinType:
       return "Numeric minimum compatibility";
   }
-  assert(false && "Unreachable!");
+  CM_UNREACHABLE;
   return "";
 }
 
@@ -381,7 +381,7 @@ static std::string compatibilityAgree(CompatibleType t, bool dominant)
     case NumberMinType:
       return dominant ? "(Dominant)\n" : "(Ignored)\n";
   }
-  assert(false && "Unreachable!");
+  CM_UNREACHABLE;
   return "";
 }
 
@@ -524,7 +524,7 @@ std::pair<bool, char const*> consistentProperty(char const* lhs,
     case NumberMaxType:
       return consistentNumberProperty(lhs, rhs, t);
   }
-  assert(false && "Unreachable!");
+  CM_UNREACHABLE;
   return { false, nullptr };
 }
 
@@ -558,7 +558,7 @@ static std::pair<bool, std::string> consistentProperty(std::string const& lhs,
                value.first ? std::string(value.second) : null_ptr };
     }
   }
-  assert(false && "Unreachable!");
+  CM_UNREACHABLE;
   return { false, null_ptr };
 }
 

Source/cmGlobalGenerator.cxx

@@ -66,6 +66,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetExport.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmVersion.h"
 #include "cmWorkingDirectory.h"
@@ -2423,7 +2424,7 @@ bool cmGlobalGenerator::UseShortObjectNames(
       strategy = this->QtAutogenIntDirStrategy;
       break;
     default:
-      assert(false);
+      CM_UNREACHABLE;
       break;
   }
   return this->SupportsShortObjectNames() &&

Source/cmGlobalNinjaGenerator.cxx

@@ -3,7 +3,6 @@
 #include "cmGlobalNinjaGenerator.h"
 
 #include <algorithm>
-#include <cassert>
 #include <cstdio>
 #include <functional>
 #include <iterator>
@@ -57,6 +56,7 @@
 #include "cmTargetTypes.h"
 #include "cmTest.h"
 #include "cmTestGenerator.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmVersion.h"
 #include "cmake.h"
@@ -3021,7 +3021,7 @@ bool cmGlobalNinjaGenerator::WriteDyndepFile(
       case LookupMethod::IncludeQuote:
         return "include-quote"_s;
     }
-    assert(false && "unsupported lookup method");
+    CM_UNREACHABLE;
     return ""_s;
   };
 

Source/cmInstallCommand.cxx

@@ -3,7 +3,6 @@
 #include "cmInstallCommand.h"
 
 #include <algorithm>
-#include <cassert>
 #include <cstddef>
 #include <iterator>
 #include <map>
@@ -58,6 +57,7 @@
 #include "cmTarget.h"
 #include "cmTargetExport.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 
 namespace {
@@ -1490,7 +1490,7 @@ bool HandleImportedRuntimeArtifactsMode(std::vector<std::string> const& args,
         }
         break;
       default:
-        assert(false && "This should never happen");
+        CM_UNREACHABLE;
         break;
     }
 

Source/cmInstallImportedRuntimeArtifactsGenerator.cxx

@@ -2,7 +2,6 @@
    file LICENSE.rst or https://cmake.org/licensing for details.  */
 #include "cmInstallImportedRuntimeArtifactsGenerator.h"
 
-#include <cassert>
 #include <string>
 #include <utility>
 #include <vector>
@@ -16,6 +15,7 @@
 #include "cmLocalGenerator.h"
 #include "cmStringAlgorithms.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 
 namespace {
 cmsys::RegularExpression const FrameworkRegularExpression(
@@ -143,7 +143,7 @@ void cmInstallImportedRuntimeArtifactsGenerator::GenerateScriptForConfig(
       }
       break;
     default:
-      assert(false && "This should never happen");
+      CM_UNREACHABLE;
       break;
   }
 }

Source/cmInstallTargetGenerator.cxx

@@ -33,6 +33,7 @@
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmake.h"
 
@@ -246,8 +247,7 @@ cmInstallTargetGenerator::Files cmInstallTargetGenerator::GetFiles(
     case cm::TargetType::INTERFACE_LIBRARY:
       // Not reachable. We never create a cmInstallTargetGenerator for
       // an INTERFACE_LIBRARY.
-      assert(false &&
-             "INTERFACE_LIBRARY targets have no installable outputs.");
+      CM_UNREACHABLE;
       break;
 
     case cm::TargetType::OBJECT_LIBRARY: {

Source/cmNinjaNormalTargetGenerator.cxx

@@ -3,7 +3,6 @@
 #include "cmNinjaNormalTargetGenerator.h"
 
 #include <algorithm>
-#include <cassert>
 #include <iterator>
 #include <set>
 #include <sstream>
@@ -44,6 +43,7 @@
 #include "cmSystemTools.h"
 #include "cmTarget.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 
 cmNinjaNormalTargetGenerator::cmNinjaNormalTargetGenerator(
@@ -831,7 +831,7 @@ std::vector<std::string> cmNinjaNormalTargetGenerator::ComputeLinkCmd(
     case cm::TargetType::EXECUTABLE:
       break;
     default:
-      assert(false && "Unexpected target type");
+      CM_UNREACHABLE;
   }
   return std::move(linkCmds.data());
 }

Source/cmState.cxx

@@ -27,6 +27,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetTypes.h"
+#include "cmUnreachable.h"
 #include "cmake.h"
 
 namespace cmStateDetail {
@@ -78,7 +79,7 @@ std::string const& cmState::GetTargetTypeName(cm::TargetType targetType)
     case cm::TargetType::UNKNOWN_LIBRARY:
       return propUNKNOWN_LIBRARY;
   }
-  assert(false && "Unexpected target type");
+  CM_UNREACHABLE;
   return propEmpty;
 }
 

Source/cmTarget.cxx

@@ -44,6 +44,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetPropertyComputer.h"
+#include "cmUnreachable.h"
 #include "cmValue.h"
 #include "cmXcFramework.h"
 #include "cmake.h"
@@ -2972,7 +2973,7 @@ bool cmTarget::IsNormal() const
     case Visibility::Foreign:
       return false;
   }
-  assert(false && "unknown visibility (IsNormal)");
+  CM_UNREACHABLE;
   return false;
 }
 
@@ -2987,7 +2988,7 @@ bool cmTarget::IsSynthetic() const
     case Visibility::Foreign:
       return false;
   }
-  assert(false && "unknown visibility (IsSynthetic)");
+  CM_UNREACHABLE;
   return false;
 }
 
@@ -3002,7 +3003,7 @@ bool cmTargetInternals::IsImported() const
     case cmTarget::Visibility::Generated:
       return false;
   }
-  assert(false && "unknown visibility (IsImported)");
+  CM_UNREACHABLE;
   return false;
 }
 
@@ -3022,7 +3023,7 @@ bool cmTarget::IsImportedGloballyVisible() const
     case Visibility::Foreign:
       return false;
   }
-  assert(false && "unknown visibility (IsImportedGloballyVisible)");
+  CM_UNREACHABLE;
   return false;
 }
 
@@ -3037,7 +3038,7 @@ bool cmTarget::IsForeign() const
     case Visibility::ImportedGlobally:
       return false;
   }
-  assert(false && "unknown visibility (isForeign)");
+  CM_UNREACHABLE;
   return false;
 }
 

Source/cmUnreachable.h

@@ -0,0 +1,22 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file LICENSE.rst or https://cmake.org/licensing for details.  */
+#pragma once
+
+#if defined(NDEBUG)
+#  include <cm/utility>
+#  define CM_UNREACHABLE                                                      \
+    do {                                                                      \
+      cm::unreachable();                                                      \
+    } while (false)
+#else
+#  include <cassert>
+#  include <cstdlib>
+#  include <iostream>
+#  define CM_UNREACHABLE                                                      \
+    do {                                                                      \
+      std::cerr << "unreachable code path at " << __FILE__ << ':' << __LINE__ \
+                << " in " << __func__ << '\n';                                \
+      assert(false && "unreachable code path");                               \
+      std::abort();                                                           \
+    } while (false)
+#endif

Source/cmVisualStudioSlnParser.cxx

@@ -14,6 +14,7 @@
 
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
+#include "cmUnreachable.h"
 #include "cmVisualStudioSlnData.h"
 
 namespace {
@@ -182,7 +183,7 @@ LineFormat cmVisualStudioSlnParser::State::NextLineFormat() const
     case FileStateIgnore:
       return LineVerbatim;
     default:
-      assert(false);
+      CM_UNREACHABLE;
       return LineVerbatim;
   }
 }

Source/cmXCodeObject.cxx

@@ -7,6 +7,8 @@
 #include <cm/string_view>
 #include <cmext/string_view>
 
+#include "cmUnreachable.h"
+
 char const* cmXCodeObject::PBXTypeNames[] = {
   /* clang-format needs this comment to break after the opening brace */
   "PBXGroup",
@@ -68,7 +70,8 @@ bool cmXCodeObject::IsEmpty() const
     case OBJECT:
       return this->Object == nullptr;
   }
-  return true; // unreachable, but quiets warnings
+  CM_UNREACHABLE;
+  return true;
 }
 
 void cmXCodeObject::Indent(int level, std::ostream& out)