[Test][FileCheck] Fix use of undef var

[thopre]

Summary

The test related to directives with prefix NUMEXPR-CONSTRAINT-NOMATCH
refers to the numeric variable UNSI which is defined by a directive with
prefix CHECK not enabled on the lit command-line. Rather than adding the
prefix CHECK to the lit command-line, this commit defined variable UNSI
in a new NUMEXPR-CONSTRAINT-NOMATCH prefixed directive. The directive
needs to contain more than just the variable otherwise the error message
from FileCheck is about the wrong line being matched.

[jhenderson]

llvm/test/FileCheck/numeric-expression.txt

249

Rather than requiring the whole CHECK patterns to be checked as part of this, would it make more sense to just use -D to define UNSI, something like the suggested edit?

[thopre]

Define UNSI with the rightly prefixed directive

[jhenderson]

LGTM.

llvm/test/FileCheck/numeric-expression.txt

 11  // CHECK-NEXT: {{^}}[[#==UNSI]]
 11  // CHECK-NEXT: {{^}}[[# == UNSI]]
 12  // CHECK-NEXT: {{^}}[[#UNSI2: == UNSI + 1]]
 12  // CHECK-NEXT: {{^}}[[#==UNSI2]]
 
 ; Numeric expressions in default matching format and explicit matching rule using
 ; variable defined on other lines with match failure.
 RUN: %ProtectFileCheckOutput \
 RUN: not FileCheck --check-prefix NUMEXPR-CONSTRAINT-NOMATCH --input-file %s %s 2>&1 \
 RUN:   | FileCheck --check-prefix NUMEXPR-CONSTRAINT-NOMATCH-MSG --strict-whitespace %s
 
 USE DEF FMT EXPL NO MATCH
-12
+UNSI=11
+UNSI: 12
 NUMEXPR-CONSTRAINT-NOMATCH-LABEL: USE DEF FMT EXPL NO MATCH
-NUMEXPR-CONSTRAINT-NOMATCH-NEXT: [[#==UNSI]]
+NUMEXPR-CONSTRAINT-NOMATCH-NEXT: UNSI=[[#UNSI:]]
+NUMEXPR-CONSTRAINT-NOMATCH-NEXT: UNSI: [[#==UNSI]]
 NUMEXPR-CONSTRAINT-NOMATCH-MSG: numeric-expression.txt:[[#@LINE-1]]:34: error: {{N}}UMEXPR-CONSTRAINT-NOMATCH-NEXT: expected string not found in input
-NUMEXPR-CONSTRAINT-NOMATCH-MSG-NEXT: {{N}}UMEXPR-CONSTRAINT-NOMATCH-NEXT: {{\[\[#==UNSI\]\]}}
-NUMEXPR-CONSTRAINT-NOMATCH-MSG-NEXT:   {{^}}                                 ^{{$}}
+NUMEXPR-CONSTRAINT-NOMATCH-MSG-NEXT:  {{N}}UMEXPR-CONSTRAINT-NOMATCH-NEXT: UNSI: {{\[\[#==UNSI\]\]}}
+NUMEXPR-CONSTRAINT-NOMATCH-MSG-NEXT: {{^}}                                 ^{{$}}
 
 ; Empty numeric expression with matching constraint.
 RUN: %ProtectFileCheckOutput \
 RUN: not FileCheck --check-prefix EMPTY-NUMEXPR-CONSTRAINT --input-file %s %s 2>&1 \
 RUN:   | FileCheck --check-prefix EMPTY-NUMEXPR-CONSTRAINT-MSG --strict-whitespace %s
 
 EMPTY NUMEXPR USE WITH CONSTRAINT
 18