Don't allow multiple symbol tables in the module block.

tests_lit/parse_errs/dup-module-vst.test

Index: tests_lit/parse_errs/dup-module-vst.test
diff --git a/tests_lit/parse_errs/dup-module-vst.test b/tests_lit/parse_errs/dup-module-vst.test
new file mode 100644
index 0000000000000000000000000000000000000000..fd285317106aa2f2f6c5b3c0d2f6da46f3ebe97b
--- /dev/null
+++ b/tests_lit/parse_errs/dup-module-vst.test
@@ -0,0 +1,22 @@
+; Test if we detect multiple module-level symbol tables in bitcode.
+
+; REQUIRES: no_minimal_build
+
+; RUN: not %pnacl_sz -bitcode-as-text %p/Inputs/dup-module-vst.tbc \
+; RUN:     -bitcode-format=pnacl -notranslate -build-on-read 2>&1 \
+; RUN:   | FileCheck %s
+
+; CHECK: Duplicate valuesymtab in module
+
+; RUN: pnacl-bcfuzz -bitcode-as-text %p/Inputs/dup-module-vst.tbc \
+; RUN:   -output - | pnacl-bcdis -no-records | FileCheck -check-prefix=ASM %s
+
+; ASM: module {  // BlockID = 8
+; ASM:   valuesymtab {  // BlockID = 14
+; ASM:     @f0 : "f";
+; ASM:   }
+; ASM:   valuesymtab {  // BlockID = 14
+; ASM:     @f0 : "f";
+; ASM:   }
+; ASM: }
+