[FileCheck] Fix @LINE value after match failure

Summary:
The value of the FileCheckNumericVariable class instance representing
the @LINE numeric variable is set and cleared respectively before and
after substitutions are made, if any. However, when a substitution
fails, the value is not cleared. This causes the next substitution of
@LINE later on to give the wrong value since setValue is a nop if the
value is already set. This is what caused failures after commit r365249.

Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar, arichardson, rnk

Subscribers: hiraditya, llvm-commits, probinson, dblaikie, grimar, arichardson, tra, rnk, kristina, hfinkel, rogfer01, JonChesterfield

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64449

llvm-svn: 365624

2 files changed, 18 insertions, 1 deletions

diff --git a/llvm/lib/Support/FileCheck.cpp b/llvm/lib/Support/FileCheck.cpp
index 03e892af274..93a3f0513fc 100644
--- a/llvm/lib/Support/FileCheck.cpp
+++ b/llvm/lib/Support/FileCheck.cpp
@@ -580,8 +580,10 @@ Expected<size_t> FileCheckPattern::match(StringRef Buffer, size_t &MatchLen,
     for (const auto &Substitution : Substitutions) {
       // Substitute and check for failure (e.g. use of undefined variable).
       Expected<std::string> Value = Substitution->getResult();
-      if (!Value)
+      if (!Value) {
+        Context->LineVariable->clearValue();
         return Value.takeError();
+      }
 
       // Plop it into the regex at the adjusted offset.
       TmpStr.insert(TmpStr.begin() + Substitution->getIndex() + InsertOffset,
diff --git a/llvm/unittests/Support/FileCheckTest.cpp b/llvm/unittests/Support/FileCheckTest.cpp
index 7fcd5bba608..58550c7b7bd 100644
--- a/llvm/unittests/Support/FileCheckTest.cpp
+++ b/llvm/unittests/Support/FileCheckTest.cpp
@@ -334,6 +334,21 @@ TEST_F(FileCheckTest, Match) {
   EXPECT_TRUE(Tester.matchExpect("19 21"));
   EXPECT_TRUE(Tester.matchExpect("18 21"));
   EXPECT_FALSE(Tester.matchExpect("18 20"));
+
+  // Check matching a numeric expression using @LINE after match failure uses
+  // the correct value for @LINE.
+  Tester.initNextPattern();
+  EXPECT_FALSE(Tester.parsePatternExpect("[[#@LINE]]"));
+  // Ok, @LINE is 4 now.
+  EXPECT_FALSE(Tester.matchExpect("4"));
+  Tester.initNextPattern();
+  // @LINE is now 5, match with substitution failure.
+  EXPECT_FALSE(Tester.parsePatternExpect("[[#UNKNOWN]]"));
+  EXPECT_TRUE(Tester.matchExpect("FOO"));
+  Tester.initNextPattern();
+  // Check that @LINE is 6 as expected.
+  EXPECT_FALSE(Tester.parsePatternExpect("[[#@LINE]]"));
+  EXPECT_FALSE(Tester.matchExpect("6"));
 }
 
 TEST_F(FileCheckTest, Substitution) {