From 2f85ec0a37d1ad75956dd81016a8c7ab90ff845b Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Thu, 12 Jan 2023 11:04:16 -0500
Subject: try_run: Avoid crash in keyword-dispatched signature when
 cross-compiling

Since commit aa9220d3a0 (try_compile: Add keyword-dispatched signature,
2022-09-02, v3.25.0-rc1~178^2) the `DoNotRunExecutable` code path may be
reached with no single source-file argument.  Do not assume it exists.

Fixes: #24295
---
 Source/cmTryRunCommand.cxx                               | 14 ++++++++------
 Tests/RunCMake/try_run/CrossCompile.cmake                |  8 ++++++++
 Tests/RunCMake/try_run/old_and_new_signature_tests.cmake |  2 ++
 3 files changed, 18 insertions(+), 6 deletions(-)
 create mode 100644 Tests/RunCMake/try_run/CrossCompile.cmake

diff --git a/Source/cmTryRunCommand.cxx b/Source/cmTryRunCommand.cxx
index 1e81195..8d62cb1 100644
--- a/Source/cmTryRunCommand.cxx
+++ b/Source/cmTryRunCommand.cxx
@@ -40,7 +40,7 @@ public:
                      std::string* runOutputStdOutContents,
                      std::string* runOutputStdErrContents);
   void DoNotRunExecutable(const std::string& runArgs,
-                          const std::string& srcFile,
+                          cm::optional<std::string> const& srcFile,
                           std::string const& compileResultVariable,
                           std::string* runOutputContents,
                           std::string* runOutputStdOutContents,
@@ -128,7 +128,7 @@ bool TryRunCommandImpl::TryRunCode(std::vector<std::string> const& argv)
       if (this->Makefile->IsOn("CMAKE_CROSSCOMPILING") &&
           !this->Makefile->IsDefinitionSet("CMAKE_CROSSCOMPILING_EMULATOR")) {
         this->DoNotRunExecutable(
-          runArgs, *arguments.SourceDirectoryOrFile,
+          runArgs, arguments.SourceDirectoryOrFile,
           *arguments.CompileResultVariable,
           captureRunOutput ? &runOutputContents : nullptr,
           captureRunOutputStdOutErr && arguments.RunOutputStdOutVariable
@@ -238,7 +238,7 @@ void TryRunCommandImpl::RunExecutable(const std::string& runArgs,
  the executable would have produced.
 */
 void TryRunCommandImpl::DoNotRunExecutable(
-  const std::string& runArgs, const std::string& srcFile,
+  const std::string& runArgs, cm::optional<std::string> const& srcFile,
   std::string const& compileResultVariable, std::string* out,
   std::string* stdOut, std::string* stdErr)
 {
@@ -421,9 +421,11 @@ void TryRunCommandImpl::DoNotRunExecutable(
 
       comment += "The ";
       comment += compileResultVariable;
-      comment += " variable holds the build result for this try_run().\n\n"
-                 "Source file   : ";
-      comment += srcFile + "\n";
+      comment += " variable holds the build result for this try_run().\n\n";
+      if (srcFile) {
+        comment += "Source file   : ";
+        comment += *srcFile + "\n";
+      }
       comment += "Executable    : ";
       comment += copyDest + "\n";
       comment += "Run arguments : ";
diff --git a/Tests/RunCMake/try_run/CrossCompile.cmake b/Tests/RunCMake/try_run/CrossCompile.cmake
new file mode 100644
index 0000000..4993768
--- /dev/null
+++ b/Tests/RunCMake/try_run/CrossCompile.cmake
@@ -0,0 +1,8 @@
+include(${CMAKE_CURRENT_SOURCE_DIR}/${try_compile_DEFS})
+
+# Pretend we are cross-compiling to take that try_run code path.
+set(CMAKE_CROSSCOMPILING 1)
+set(RUN_RESULT 0)
+try_run(RUN_RESULT COMPILE_RESULT ${try_compile_bindir_or_SOURCES}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c)
+unset(CMAKE_CROSSCOMPILING)
diff --git a/Tests/RunCMake/try_run/old_and_new_signature_tests.cmake b/Tests/RunCMake/try_run/old_and_new_signature_tests.cmake
index e1c1784..2b51eb2 100644
--- a/Tests/RunCMake/try_run/old_and_new_signature_tests.cmake
+++ b/Tests/RunCMake/try_run/old_and_new_signature_tests.cmake
@@ -11,6 +11,8 @@ run_cmake(BadLinkLibraries)
 run_cmake(BinDirEmpty)
 run_cmake(BinDirRelative)
 
+run_cmake(CrossCompile)
+
 run_cmake(WorkingDirArg)
 
 run_cmake(NoCompileOutputVariable)
-- 
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