Make tests pass when --disable-decnum

docs/content/manual/manual.yml

@@ -357,10 +357,13 @@ sections:
 
           The way in which jq handles numbers has changed over time
           and further changes are likely within the parameters set by
-          the relevant JSON standards.  The following remarks are
-          therefore offered with the understanding that they are
-          intended to be descriptive of the current version of jq and
-          should not be interpreted as being prescriptive:
+          the relevant JSON standards.  Moreover, build configuration
+          options can alter how jq processes numbers.
+
+          The following remarks are therefore offered with the
+          understanding that they are intended to be descriptive of the
+          current version of jq and should not be interpreted as being
+          prescriptive:
 
           (1) Any arithmetic operation on a number that has not
           already been converted to an IEEE754 double precision
@@ -368,9 +371,10 @@ sections:
           representation.
 
           (2) jq will attempt to maintain the original decimal
-          precision of number literals, but in expressions such
-          `1E1234567890`, precision will be lost if the exponent is
-          too large.
+          precision of number literals (if the `--disable-decnum`
+          build configuration option was not used), but in expressions
+          such `1E1234567890`, precision will be lost if the exponent
+          is too large.
 
           (3) In jq programs, a leading minus sign will trigger the
           conversion of the number to an IEEE754 representation.
@@ -379,6 +383,12 @@ sections:
           big decimal representation of numbers if available, as
           illustrated in one of the following examples.
 
+          The examples below use the builtin function `have_decnum` in
+          order to demonstrate the expected effects of using / not
+          using the `--disable-decnum` build configuration option, and
+          also to allow automated tests derived from these examples to
+          pass regardless of whether that option is used.
+
         examples:
           - program: '.'
             input: '"Hello, world!"'
@@ -388,21 +398,21 @@ sections:
             input: '0.12345678901234567890123456789'
             output: ['0.12345678901234567890123456789']
 
-          - program: '[., tojson]'
+          - program: '[., tojson] | . == if have_decnum then [12345678909876543212345,"12345678909876543212345"] else [12345678909876543000000,"12345678909876543000000"] end'
             input: '12345678909876543212345'
-            output: ['[12345678909876543212345,"12345678909876543212345"]']
+            output: ['true']
 
           - program: '. < 0.12345678901234567890123456788'
             input: '0.12345678901234567890123456789'
             output: ['false']
 
-          - program: 'map([., . == 1]) | tojson'
+          - program: 'map([., . == 1]) | tojson | . == if have_decnum then "[[1,true],[1.000,true],[1.0,true],[1.00,true]]" else "[[1,true],[1,true],[1,true],[1,true]]" end'
             input: '[1, 1.000, 1.0, 100e-2]'
-            output: ['"[[1,true],[1.000,true],[1.0,true],[1.00,true]]"']
+            output: ['true']
 
-          - program: '. as $big | [$big, $big + 1] | map(. > 10000000000000000000000000000000)'
+          - program: '. as $big | [$big, $big + 1] | map(. > 10000000000000000000000000000000) | . == if have_decnum then [true, false] else [false, false] end'
             input: '10000000000000000000000000000001'
-            output: ['[true, false]']
+            output: ['true']
 
       - title: "Object Identifier-Index: `.foo`, `.foo.bar`"
         body: |
@@ -1992,6 +2002,19 @@ sections:
             output:
               - '[{"a":{"b":2}}]'
 
+      - title: "`have_literal_numbers`"
+        body: |
+
+          This builtin returns true if jq's build configuration
+          includes support for preservation of input number literals.
+
+      - title: "`have_decnum`"
+        body: |
+
+          This builtin returns true if jq was built with "decnum",
+          which is the current literal number preserving numeric
+          backend implementation for jq.
+
       - title: "`$JQ_BUILD_CONFIGURATION`"
         body: |