Merge topic 'capture-clang-tidy-errors'

80ebc55a cmake: Report if the <LANG>_CLANG_TIDY tool exits with non-zero
ce1abfa4 cmake: If ldd for LINK_WHAT_YOU_USE fails to run then report why
44de6157 cmake: Comment why we ignore the include-what-you-use return code

Tests/RunCMake/ClangTidy/C-bad-Build-result.txt

@@ -0,0 +1 @@
+[^0]

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'

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)

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)

Tests/RunCMake/pseudo_iwyu.c

@@ -3,5 +3,6 @@
 int main(void)
 {
   fprintf(stderr, "should add these lines:\n#include <...>\n");
-  return 0;
+  /* include-what-you-use always returns failure */
+  return 1;
 }

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;