[Clang] Fix crash when -header-include-filtering is not specified (llvm#136232)

If you specify -header-include-format=json, the only filtering option
currently supported is -header-include-filtering=only-direct-system. If
you specify some other filtering option, Clang gives an error message.
But, if you do not specify the filtering option at all, Clang crashes
when producing the error message, since it tries to get the value of the
unused option.

Author: bob-wilson

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -399,8 +399,14 @@ def err_drv_print_header_env_var : Error<
   "environment variable CC_PRINT_HEADERS_%select{FORMAT|FILTERING}0 has invalid value %1">;
 def err_drv_print_header_env_var_combination : Error<
   "unsupported combination: CC_PRINT_HEADERS_FORMAT=%0 and CC_PRINT_HEADERS_FILTERING=%1">;
-def err_drv_print_header_env_var_combination_cc1 : Error<
+def err_drv_print_header_env_var_invalid_format : Error<
+  "environment variable CC_PRINT_HEADERS_FORMAT=%0 requires a compatible value for CC_PRINT_HEADERS_FILTERING">;
+def err_drv_print_header_cc1_invalid_combination : Error<
   "unsupported combination: -header-include-format=%0 and -header-include-filtering=%1">;
+def err_drv_print_header_cc1_invalid_filtering : Error<
+  "-header-include-filtering=%0 requires a compatible value for -header-include-format">;
+def err_drv_print_header_cc1_invalid_format : Error<
+  "-header-include-format=%0 requires a compatible value for -header-include-filtering">;
 
 def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">, InGroup<Deprecated>;
 def warn_drv_optimization_value : Warning<"optimization level '%0' is not supported; using '%1%2' instead">,

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2541,13 +2541,25 @@ static bool ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
 
   // Check for invalid combinations of header-include-format
   // and header-include-filtering.
-  if ((Opts.HeaderIncludeFormat == HIFMT_Textual &&
-       Opts.HeaderIncludeFiltering != HIFIL_None) ||
-      (Opts.HeaderIncludeFormat == HIFMT_JSON &&
-       Opts.HeaderIncludeFiltering != HIFIL_Only_Direct_System))
-    Diags.Report(diag::err_drv_print_header_env_var_combination_cc1)
-        << Args.getLastArg(OPT_header_include_format_EQ)->getValue()
-        << Args.getLastArg(OPT_header_include_filtering_EQ)->getValue();
+  if (Opts.HeaderIncludeFormat == HIFMT_Textual &&
+      Opts.HeaderIncludeFiltering != HIFIL_None) {
+    if (Args.hasArg(OPT_header_include_format_EQ))
+      Diags.Report(diag::err_drv_print_header_cc1_invalid_combination)
+          << headerIncludeFormatKindToString(Opts.HeaderIncludeFormat)
+          << headerIncludeFilteringKindToString(Opts.HeaderIncludeFiltering);
+    else
+      Diags.Report(diag::err_drv_print_header_cc1_invalid_filtering)
+          << headerIncludeFilteringKindToString(Opts.HeaderIncludeFiltering);
+  } else if (Opts.HeaderIncludeFormat == HIFMT_JSON &&
+             Opts.HeaderIncludeFiltering == HIFIL_None) {
+    if (Args.hasArg(OPT_header_include_filtering_EQ))
+      Diags.Report(diag::err_drv_print_header_cc1_invalid_combination)
+          << headerIncludeFormatKindToString(Opts.HeaderIncludeFormat)
+          << headerIncludeFilteringKindToString(Opts.HeaderIncludeFiltering);
+    else
+      Diags.Report(diag::err_drv_print_header_cc1_invalid_format)
+          << headerIncludeFormatKindToString(Opts.HeaderIncludeFormat);
+  }
 
   return Diags.getNumErrors() == NumErrorsBefore;
 }

clang/test/Preprocessor/print-header-json.c

@@ -1,11 +1,16 @@
 // RUN: %clang_cc1 -E -header-include-format=json -header-include-filtering=only-direct-system -header-include-file %t.txt -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s
 // RUN: cat %t.txt | FileCheck %s --check-prefix=SUPPORTED
+
 // RUN: not %clang_cc1 -E -header-include-format=textual -header-include-filtering=only-direct-system -header-include-file %t.txt -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED0
 // RUN: not %clang_cc1 -E -header-include-format=json -header-include-filtering=none -header-include-file %t.txt -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED1
-// RUN: rm %t.txt
-// RUN: env CC_PRINT_HEADERS_FORMAT=json CC_PRINT_HEADERS_FILTERING=only-direct-system CC_PRINT_HEADERS_FILE=%t.txt %clang -fsyntax-only -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null
 // RUN: env CC_PRINT_HEADERS_FORMAT=textual CC_PRINT_HEADERS_FILTERING=only-direct-system CC_PRINT_HEADERS_FILE=%t.txt not %clang -fsyntax-only -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED2
 // RUN: env CC_PRINT_HEADERS_FORMAT=json CC_PRINT_HEADERS_FILTERING=none CC_PRINT_HEADERS_FILE=%t.txt not %clang -fsyntax-only -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED3
+// RUN: env CC_PRINT_HEADERS_FORMAT=json CC_PRINT_HEADERS_FILE=%t.txt not %clang -fsyntax-only -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED4
+// RUN: not %clang_cc1 -E -header-include-filtering=only-direct-system -header-include-file %t.txt -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED5
+// RUN: not %clang_cc1 -E -header-include-format=json -header-include-file %t.txt -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNSUPPORTED6
+
+// RUN: rm %t.txt
+// RUN: env CC_PRINT_HEADERS_FORMAT=json CC_PRINT_HEADERS_FILTERING=only-direct-system CC_PRINT_HEADERS_FILE=%t.txt %clang -fsyntax-only -I %S/Inputs/print-header-json -isystem %S/Inputs/print-header-json/system %s -o /dev/null
 // RUN: cat %t.txt | FileCheck %s --check-prefix=SUPPORTED
 
 #include "system0.h"
@@ -18,3 +23,6 @@
 // UNSUPPORTED1: error: unsupported combination: -header-include-format=json and -header-include-filtering=none
 // UNSUPPORTED2: error: unsupported combination: CC_PRINT_HEADERS_FORMAT=textual and CC_PRINT_HEADERS_FILTERING=only-direct-system
 // UNSUPPORTED3: error: unsupported combination: CC_PRINT_HEADERS_FORMAT=json and CC_PRINT_HEADERS_FILTERING=none
+// UNSUPPORTED4: error: environment variable CC_PRINT_HEADERS_FORMAT=json requires a compatible value for CC_PRINT_HEADERS_FILTERING
+// UNSUPPORTED5: error: -header-include-filtering=only-direct-system requires a compatible value for -header-include-format
+// UNSUPPORTED6: error: -header-include-format=json requires a compatible value for -header-include-filtering

clang/tools/driver/driver.cpp

@@ -167,6 +167,11 @@ static bool SetBackdoorDriverOutputsFromEnvVars(Driver &TheDriver) {
       }
 
       const char *FilteringStr = ::getenv("CC_PRINT_HEADERS_FILTERING");
+      if (!FilteringStr) {
+        TheDriver.Diag(clang::diag::err_drv_print_header_env_var_invalid_format)
+            << EnvVar;
+        return false;
+      }
       HeaderIncludeFilteringKind Filtering;
       if (!stringToHeaderIncludeFiltering(FilteringStr, Filtering)) {
         TheDriver.Diag(clang::diag::err_drv_print_header_env_var)