cmake: Report if the <LANG>_CLANG_TIDY tool exits with non-zero

When using `<LANG>_CLANG_TIDY` our internal launcher for the tool must
capture its return code and stderr and report them on failure.
Otherwise incorrect command lines silently fail.

Closes: #16435

5 files changed, 13 insertions, 0 deletions

diff --git a/Tests/RunCMake/ClangTidy/C-bad-Build-result.txt b/Tests/RunCMake/ClangTidy/C-bad-Build-result.txt
new file mode 100644
index 0000000..d197c91
--- /dev/null
+++ b/Tests/RunCMake/ClangTidy/C-bad-Build-result.txt
@@ -0,0 +1 @@
+[^0]
diff --git a/Tests/RunCMake/ClangTidy/C-bad-Build-stdout.txt b/Tests/RunCMake/ClangTidy/C-bad-Build-stdout.txt
new file mode 100644
index 0000000..2370ce1
--- /dev/null
+++ b/Tests/RunCMake/ClangTidy/C-bad-Build-stdout.txt
@@ -0,0 +1,2 @@
+stdout from bad command line arg '-bad'
+stderr from bad command line arg '-bad'
diff --git a/Tests/RunCMake/ClangTidy/C-bad.cmake b/Tests/RunCMake/ClangTidy/C-bad.cmake
new file mode 100644
index 0000000..aa54c08
--- /dev/null
+++ b/Tests/RunCMake/ClangTidy/C-bad.cmake
@@ -0,0 +1,3 @@
+enable_language(C)
+set(CMAKE_C_CLANG_TIDY "${PSEUDO_TIDY}" -bad)
+add_executable(main main.c)
diff --git a/Tests/RunCMake/ClangTidy/RunCMakeTest.cmake b/Tests/RunCMake/ClangTidy/RunCMakeTest.cmake
index 27cd922..2f41e50 100644
--- a/Tests/RunCMake/ClangTidy/RunCMakeTest.cmake
+++ b/Tests/RunCMake/ClangTidy/RunCMakeTest.cmake
@@ -20,3 +20,4 @@ if (NOT RunCMake_GENERATOR STREQUAL "Watcom WMake")
   run_tidy(C-launch)
   run_tidy(CXX-launch)
 endif()
+run_tidy(C-bad)
diff --git a/Tests/RunCMake/pseudo_tidy.c b/Tests/RunCMake/pseudo_tidy.c
index c950d03..2feeb0f 100644
--- a/Tests/RunCMake/pseudo_tidy.c
+++ b/Tests/RunCMake/pseudo_tidy.c
@@ -1,9 +1,15 @@
 #include <stdio.h>
+#include <string.h>
 
 int main(int argc, char* argv[])
 {
   int i;
   for (i = 1; i < argc; ++i) {
+    if (strcmp(argv[i], "-bad") == 0) {
+      fprintf(stdout, "stdout from bad command line arg '-bad'\n");
+      fprintf(stderr, "stderr from bad command line arg '-bad'\n");
+      return 1;
+    }
     if (argv[i][0] != '-') {
       fprintf(stdout, "%s:0:0: warning: message [checker]\n", argv[i]);
       break;