project: Keep leading `0` in PROJECT_VERSION components

Introduce CMake policy `CMP0096` to make `project()` keep leading zeros
in version components.  As a side effect, it now allows really long
version numbers.

Fixes: #19421
Co-Author: Brad King <[email protected]>

Help/manual/cmake-policies.7.rst

@@ -57,6 +57,7 @@ Policies Introduced by CMake 3.16
 .. toctree::
    :maxdepth: 1
 
+   CMP0096: project() preserves leading zeros in version components. </policy/CMP0096>
    CMP0095: RPATH entries are properly escaped in the intermediary CMake install script. </policy/CMP0095>
 
 Policies Introduced by CMake 3.15

Help/policy/CMP0096.rst

@@ -0,0 +1,25 @@
+CMP0096
+-------
+
+The :command:`project` command preserves leading zeros in version components.
+
+When a ``VERSION <major>[.<minor>[.<patch>[.<tweak>]]]]`` argument is given
+to the :command:`project` command, it stores the version string in the
+``PROJECT_VERSION`` variable and stores individual integer version components
+in ``PROJECT_VERSION_{MAJOR,MINOR,PATCH,TWEAK}`` variables (see policy
+:policy:`CMP0048`).  CMake 3.15 and below dropped leading zeros from each
+component.  CMake 3.16 and higher prefer to preserve leading zeros.  This
+policy provides compatibility for projects that have not been updated to
+expect the new behavior.
+
+The ``OLD`` behavior of this policy drops leading zeros in all components,
+e.g.  such that version ``1.07.06`` becomes ``1.7.6``.  The ``NEW`` behavior
+of this policy preserves the leading zeros in all components, such that
+version ``1.07.06`` remains unchanged.
+
+This policy was introduced in CMake version 3.16.  Unlike many policies, CMake
+version |release| does *not* warn when this policy is not set and simply uses
+the ``OLD`` behavior.  Use the :command:`cmake_policy` command to set it to
+``OLD`` or ``NEW`` explicitly.
+
+.. include:: DEPRECATED.txt

Help/release/dev/project-version-0.rst

@@ -0,0 +1,5 @@
+project-version-0
+-----------------
+
+* The :command:`project` no longer strips leading zeros in version components.
+  See policy :policy:`CMP0096`.

Source/cmPolicies.h

@@ -283,7 +283,10 @@ class cmMakefile;
   SELECT(POLICY, CMP0095,                                                     \
          "RPATH entries are properly escaped in the intermediary CMake "      \
          "install script.",                                                   \
-         3, 16, 0, cmPolicies::WARN)
+         3, 16, 0, cmPolicies::WARN)                                          \
+  SELECT(POLICY, CMP0096,                                                     \
+         "project() preserves leading zeros in version components.", 3, 16,   \
+         0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \

Source/cmProjectCommand.cxx

@@ -3,9 +3,12 @@
 #include "cmProjectCommand.h"
 
 #include "cmsys/RegularExpression.hxx"
+#include <array>
+#include <cstdio>
 #include <functional>
+#include <limits>
 #include <sstream>
-#include <stdio.h>
+#include <utility>
 
 #include "cmAlgorithms.h"
 #include "cmMakefile.h"
@@ -220,44 +223,69 @@ bool cmProjectCommand::InitialPass(std::vector<std::string> const& args,
       return true;
     }
 
+    cmPolicies::PolicyStatus const cmp0096 =
+      this->Makefile->GetPolicyStatus(cmPolicies::CMP0096);
+
     constexpr std::size_t MAX_VERSION_COMPONENTS = 4u;
-    std::string vs;
-    char vb[MAX_VERSION_COMPONENTS][64];
-    unsigned int v[MAX_VERSION_COMPONENTS] = { 0, 0, 0, 0 };
-    int vc =
-      sscanf(version.c_str(), "%u.%u.%u.%u", &v[0], &v[1], &v[2], &v[3]);
-    for (auto i = 0u; i < MAX_VERSION_COMPONENTS; ++i) {
-      if (int(i) < vc) {
-        sprintf(vb[i], "%u", v[i]);
-        vs += &"."[size_t(i == 0)];
-        vs += vb[i];
-      } else {
-        vb[i][0] = 0;
+    std::string version_string;
+    std::array<std::string, MAX_VERSION_COMPONENTS> version_components;
+
+    if (cmp0096 == cmPolicies::OLD || cmp0096 == cmPolicies::WARN) {
+      char vb[MAX_VERSION_COMPONENTS][std::numeric_limits<unsigned>::digits10];
+      unsigned v[MAX_VERSION_COMPONENTS] = { 0, 0, 0, 0 };
+      const int vc = std::sscanf(version.c_str(), "%u.%u.%u.%u", &v[0], &v[1],
+                                 &v[2], &v[3]);
+      for (auto i = 0u; i < MAX_VERSION_COMPONENTS; ++i) {
+        if (int(i) < vc) {
+          std::sprintf(vb[i], "%u", v[i]);
+          version_string += &"."[std::size_t(i == 0)];
+          version_string += vb[i];
+          version_components[i] = vb[i];
+        } else {
+          vb[i][0] = '\x00';
+        }
+      }
+    } else {
+      // The regex above verified that we have a .-separated string of
+      // non-negative integer components.  Keep the original string.
+      version_string = std::move(version);
+      // Split the integer components.
+      auto components = cmSystemTools::SplitString(version_string, '.');
+      for (auto i = 0u; i < components.size(); ++i) {
+        version_components[i] = std::move(components[i]);
       }
     }
 
     std::string vv;
     vv = projectName + "_VERSION";
-    this->Makefile->AddDefinition("PROJECT_VERSION", vs.c_str());
-    this->Makefile->AddDefinition(vv, vs.c_str());
+    this->Makefile->AddDefinition("PROJECT_VERSION", version_string.c_str());
+    this->Makefile->AddDefinition(vv, version_string.c_str());
     vv = projectName + "_VERSION_MAJOR";
-    this->Makefile->AddDefinition("PROJECT_VERSION_MAJOR", vb[0]);
-    this->Makefile->AddDefinition(vv, vb[0]);
+    this->Makefile->AddDefinition("PROJECT_VERSION_MAJOR",
+                                  version_components[0].c_str());
+    this->Makefile->AddDefinition(vv, version_components[0].c_str());
     vv = projectName + "_VERSION_MINOR";
-    this->Makefile->AddDefinition("PROJECT_VERSION_MINOR", vb[1]);
-    this->Makefile->AddDefinition(vv, vb[1]);
+    this->Makefile->AddDefinition("PROJECT_VERSION_MINOR",
+                                  version_components[1].c_str());
+    this->Makefile->AddDefinition(vv, version_components[1].c_str());
     vv = projectName + "_VERSION_PATCH";
-    this->Makefile->AddDefinition("PROJECT_VERSION_PATCH", vb[2]);
-    this->Makefile->AddDefinition(vv, vb[2]);
+    this->Makefile->AddDefinition("PROJECT_VERSION_PATCH",
+                                  version_components[2].c_str());
+    this->Makefile->AddDefinition(vv, version_components[2].c_str());
     vv = projectName + "_VERSION_TWEAK";
-    this->Makefile->AddDefinition("PROJECT_VERSION_TWEAK", vb[3]);
-    this->Makefile->AddDefinition(vv, vb[3]);
+    this->Makefile->AddDefinition("PROJECT_VERSION_TWEAK",
+                                  version_components[3].c_str());
+    this->Makefile->AddDefinition(vv, version_components[3].c_str());
     // Also, try set top level variables
-    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION", vs.c_str());
-    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_MAJOR", vb[0]);
-    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_MINOR", vb[1]);
-    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_PATCH", vb[2]);
-    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_TWEAK", vb[3]);
+    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION", version_string.c_str());
+    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_MAJOR",
+                            version_components[0].c_str());
+    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_MINOR",
+                            version_components[1].c_str());
+    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_PATCH",
+                            version_components[2].c_str());
+    TopLevelCMakeVarCondSet("CMAKE_PROJECT_VERSION_TWEAK",
+                            version_components[3].c_str());
   } else if (cmp0048 != cmPolicies::OLD) {
     // Set project VERSION variables to empty
     std::vector<std::string> vv = { "PROJECT_VERSION",

Tests/RunCMake/project/CMP0096-NEW-stdout.txt

@@ -0,0 +1,30 @@
+-- PROJECT_VERSION='2019.07.06'
+-- DateVersion_VERSION='2019.07.06'
+-- PROJECT_VERSION_MAJOR='2019'
+-- DateVersion_VERSION_MAJOR='2019'
+-- PROJECT_VERSION_MINOR='07'
+-- DateVersion_VERSION_MINOR='07'
+-- PROJECT_VERSION_PATCH='06'
+-- DateVersion_VERSION_PATCH='06'
+-- PROJECT_VERSION_TWEAK=''
+-- DateVersion_VERSION_TWEAK=''
+-- PROJECT_VERSION='4294967297'
+-- LongVersion_VERSION='4294967297'
+-- PROJECT_VERSION_MAJOR='4294967297'
+-- LongVersion_VERSION_MAJOR='4294967297'
+-- PROJECT_VERSION_MINOR=''
+-- LongVersion_VERSION_MINOR=''
+-- PROJECT_VERSION_PATCH=''
+-- LongVersion_VERSION_PATCH=''
+-- PROJECT_VERSION_TWEAK=''
+-- LongVersion_VERSION_TWEAK=''
+-- PROJECT_VERSION='0009999999999.0009999999999.0009999999999.0009999999999'
+-- VeryLongVersion_VERSION='0009999999999.0009999999999.0009999999999.0009999999999'
+-- PROJECT_VERSION_MAJOR='0009999999999'
+-- VeryLongVersion_VERSION_MAJOR='0009999999999'
+-- PROJECT_VERSION_MINOR='0009999999999'
+-- VeryLongVersion_VERSION_MINOR='0009999999999'
+-- PROJECT_VERSION_PATCH='0009999999999'
+-- VeryLongVersion_VERSION_PATCH='0009999999999'
+-- PROJECT_VERSION_TWEAK='0009999999999'
+-- VeryLongVersion_VERSION_TWEAK='0009999999999'

Tests/RunCMake/project/CMP0096-NEW.cmake

@@ -0,0 +1,6 @@
+cmake_policy(SET CMP0048 NEW)
+cmake_policy(SET CMP0096 NEW)
+include(CMP0096-common.cmake)
+
+project(VeryLongVersion VERSION 0009999999999.0009999999999.0009999999999.0009999999999 LANGUAGES NONE)
+print_versions(VeryLongVersion)

Tests/RunCMake/project/CMP0096-OLD-stdout.txt

@@ -0,0 +1,20 @@
+-- PROJECT_VERSION='2019.7.6'
+-- DateVersion_VERSION='2019.7.6'
+-- PROJECT_VERSION_MAJOR='2019'
+-- DateVersion_VERSION_MAJOR='2019'
+-- PROJECT_VERSION_MINOR='7'
+-- DateVersion_VERSION_MINOR='7'
+-- PROJECT_VERSION_PATCH='6'
+-- DateVersion_VERSION_PATCH='6'
+-- PROJECT_VERSION_TWEAK=''
+-- DateVersion_VERSION_TWEAK=''
+-- PROJECT_VERSION='(1|4294967295)'
+-- LongVersion_VERSION='(1|4294967295)'
+-- PROJECT_VERSION_MAJOR='(1|4294967295)'
+-- LongVersion_VERSION_MAJOR='(1|4294967295)'
+-- PROJECT_VERSION_MINOR=''
+-- LongVersion_VERSION_MINOR=''
+-- PROJECT_VERSION_PATCH=''
+-- LongVersion_VERSION_PATCH=''
+-- PROJECT_VERSION_TWEAK=''
+-- LongVersion_VERSION_TWEAK=''

Tests/RunCMake/project/CMP0096-OLD.cmake

@@ -0,0 +1,3 @@
+cmake_policy(SET CMP0048 NEW)
+cmake_policy(SET CMP0096 OLD)
+include(CMP0096-common.cmake)

Tests/RunCMake/project/CMP0096-WARN-stdout.txt

@@ -0,0 +1,20 @@
+-- PROJECT_VERSION='2019.7.6'
+-- DateVersion_VERSION='2019.7.6'
+-- PROJECT_VERSION_MAJOR='2019'
+-- DateVersion_VERSION_MAJOR='2019'
+-- PROJECT_VERSION_MINOR='7'
+-- DateVersion_VERSION_MINOR='7'
+-- PROJECT_VERSION_PATCH='6'
+-- DateVersion_VERSION_PATCH='6'
+-- PROJECT_VERSION_TWEAK=''
+-- DateVersion_VERSION_TWEAK=''
+-- PROJECT_VERSION='(1|4294967295)'
+-- LongVersion_VERSION='(1|4294967295)'
+-- PROJECT_VERSION_MAJOR='(1|4294967295)'
+-- LongVersion_VERSION_MAJOR='(1|4294967295)'
+-- PROJECT_VERSION_MINOR=''
+-- LongVersion_VERSION_MINOR=''
+-- PROJECT_VERSION_PATCH=''
+-- LongVersion_VERSION_PATCH=''
+-- PROJECT_VERSION_TWEAK=''
+-- LongVersion_VERSION_TWEAK=''

Tests/RunCMake/project/CMP0096-WARN.cmake

@@ -0,0 +1,3 @@
+cmake_policy(SET CMP0048 NEW)
+
+include(CMP0096-common.cmake)

Tests/RunCMake/project/CMP0096-common.cmake

@@ -0,0 +1,9 @@
+include(PrintVersions.cmake)
+
+# Test leading zeros motivating this policy.
+project(DateVersion VERSION 2019.07.06 LANGUAGES NONE)
+print_versions(DateVersion)
+
+# Overflow version component in OLD behavior.
+project(LongVersion VERSION 4294967297 #[[ uint32_max + 2 ]] LANGUAGES NONE)
+print_versions(LongVersion)

Tests/RunCMake/project/RunCMakeTest.cmake

@@ -27,3 +27,7 @@ run_cmake(CMP0048-OLD)
 run_cmake(CMP0048-OLD-VERSION)
 run_cmake(CMP0048-WARN)
 run_cmake(CMP0048-NEW)
+
+run_cmake(CMP0096-WARN)
+run_cmake(CMP0096-OLD)
+run_cmake(CMP0096-NEW)