Merge topic 'if-diagnostic' into release-4.4

597c573d7d if: Add `DIAGNOSTIC <category>` condition

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !12181

Help/command/if.rst

@@ -43,8 +43,9 @@ Compound conditions are evaluated in the following order of precedence:
 
 2. Unary tests such as:
 
-  * The `Existence Checks`_ :cref:`COMMAND`, :cref:`POLICY`, :cref:`TARGET`,
-    :cref:`TEST`, :cref:`EXISTS`, and :cref:`DEFINED`.
+  * The `Existence Checks`_ :cref:`COMMAND`, :cref:`DEFINED`,
+    :cref:`DIAGNOSTIC`, :cref:`EXISTS`, :cref:`POLICY`, :cref:`TARGET`, and
+    :cref:`TEST`.
   * The `File Operations`_ :cref:`IS_READABLE`, :cref:`IS_WRITABLE`,
     :cref:`IS_EXECUTABLE`, :cref:`IS_DIRECTORY`, :cref:`IS_SYMLINK`, and
     :cref:`IS_ABSOLUTE`.
@@ -131,6 +132,12 @@ Existence Checks
   True if the given name is a command, macro or function that can be
   invoked.
 
+.. signature:: if(DIAGNOSTIC <category>)
+
+  .. versionadded:: 4.4
+
+  True if the given name is an existing diagnostic category.
+
 .. signature:: if(POLICY <policy-id>)
 
   True if the given name is an existing policy (of the form ``CMP<NNNN>``).

Help/release/4.4.rst

@@ -186,6 +186,9 @@ Commands
 * The :command:`file(READ_SYMLINK)` command gained a ``RESULT``
   option to capture errors without failing.
 
+* The :command:`if` command gained a new ``DIAGNOSTIC`` operator that evaluates
+  to true if a given diagnostic category name is known to CMake.
+
 * The :command:`include` command now has a ``NO_DIAGNOSTIC_SCOPE`` option.
 
 * The :command:`list(FILTER)` command gained a new ``PREDICATE`` mode

Source/cmConditionEvaluator.cxx

@@ -11,12 +11,14 @@
 #include <sstream>
 #include <utility>
 
+#include <cm/optional>
 #include <cm/string_view>
 #include <cmext/algorithm>
 
 #include "cmsys/RegularExpression.hxx"
 
 #include "cmCMakePath.h"
+#include "cmDiagnostics.h"
 #include "cmExpandedCommandArgument.h"
 #include "cmList.h"
 #include "cmMakefile.h"
@@ -30,6 +32,7 @@ namespace {
 auto const keyAND = "AND"_s;
 auto const keyCOMMAND = "COMMAND"_s;
 auto const keyDEFINED = "DEFINED"_s;
+auto const keyDIAGNOSTIC = "DIAGNOSTIC"_s;
 auto const keyEQUAL = "EQUAL"_s;
 auto const keyEXISTS = "EXISTS"_s;
 auto const keyIS_READABLE = "IS_READABLE"_s;
@@ -479,6 +482,13 @@ bool cmConditionEvaluator::HandleLevel1(cmArgumentList& newArgs, std::string&,
           this->Makefile.GetState()->GetCommand(args.next->GetValue())),
         args);
     }
+    // does a diagnostic exist
+    else if (this->IsKeyword(keyDIAGNOSTIC, *args.current)) {
+      newArgs.ReduceOneArg(
+        cmDiagnostics::GetDiagnosticCategory(args.next->GetValue())
+          .has_value(),
+        args);
+    }
     // does a policy exist
     else if (this->IsKeyword(keyPOLICY, *args.current)) {
       cmPolicies::PolicyID pid;

Tests/RunCMake/Diagnostics/ExistenceCheck.cmake

@@ -0,0 +1,7 @@
+if(NOT DIAGNOSTIC CMD_AUTHOR)
+  message(SEND_ERROR "existence check for CMD_AUTHOR failed?!")
+endif()
+
+if(DIAGNOSTIC BOGUS)
+  message(SEND_ERROR "existence check for bogus category succeeded?!")
+endif()

Tests/RunCMake/Diagnostics/RunCMakeTest.cmake

@@ -1,6 +1,7 @@
 include(RunCMake)
 
 run_cmake(Actions)
+run_cmake(ExistenceCheck)
 
 run_cmake_with_options(
   CacheInit