Changes to ROUNDMODE now invalidate cached string values.

22 files changed, 443 insertions, 176 deletions

diff --git a/ChangeLog b/ChangeLog
index 759c375f..d3771c2f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,31 @@
+2018-01-02         Arnold D. Robbins     <arnold@skeeve.com>
+
+	If ROUNDMODE changes, cause cached string conversions
+	to become invalid. Thanks to Nethox <nethox@gmail.com>
+	for the report. Day 1 bug from 4.1.0 release.
+
+	In all the below files, bump copyright year, too.
+
+	* array.c (value_info): Include strndmode in the output.
+	* awk.h (NODE): New member, strndmode.
+	(MPFR_round_mode): Add extern declaration.
+	(force_string_fmt): Check s->strnmode against MPFR_round_mode.
+	* awkgram.y (set_profile_text): Set n->strndmode to MPFR_round_mode.
+	* builtin.c (do_print): Remove tests and just call force_string_fmt.
+	* field.c (set_record): Set n->strndmode to MPFR_round_mode.
+	* gawk_api.c (api_sym_update_scalar): Set r->strndmode to
+	MPFR_round_mode.
+	* interpret.h (r_interpret): For Op_assign_concat, set t1->strndmode
+	to MPFR_round_mode.
+	* mpfr.c (MPFR_round_mode): Define and initialize.
+	(mpfr_format_val): Set s->strndmode to MPFR_round_mode.
+	(set_ROUNDMODE): Update MPFR_round_mode when ROUNDMODE changes
+	successfully.
+	* node.c (r_format_val): Set s->strndmode to MPFR_round_mode.
+	(make_str_node): Set r->strndmode to MPFR_round_mode.
+	* str_array.c (str_kilobytes): Update a comment.
+	* symbol.c (check_param_names): Set n.strndmode to MPFR_round_mode.
+
 2017-12-24         Arnold D. Robbins     <arnold@skeeve.com>
 
 	Avoid some compiler warnings. Thanks to Michal Jaegermann
diff --git a/array.c b/array.c
index 4ad52c9c..5d953c04 100644
--- a/array.c
+++ b/array.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2014, 2016, 2017,
+ * Copyright (C) 1986, 1988, 1989, 1991-2014, 2016, 2018,
  * the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
@@ -716,6 +716,9 @@ value_info(NODE *n)
 		fprintf(output_fp, "FMT=\"%s\"",
 					n->stfmt == STFMT_UNUSED ? "<unused>"
 					: fmt_list[n->stfmt]->stptr);
+#ifdef HAVE_MPFR
+		fprintf(output_fp, ", RNDMODE=\"%c\"", n->strndmode);
+#endif
 	}
 
 #undef PREC_NUM
diff --git a/awk.h b/awk.h
index 5eec241e..3b351c25 100644
--- a/awk.h
+++ b/awk.h
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 1986, 1988, 1989, 1991-2018 the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -369,6 +369,7 @@ typedef struct exp_node {
 				mpfr_t mpnum;
 				mpz_t mpi;
 			} nm;
+			int rndmode;
 #else
 			AWKNUM fltnum;
 #endif
@@ -493,6 +494,7 @@ typedef struct exp_node {
 #define stlen	sub.val.slen
 #define valref	sub.val.sref
 #define stfmt	sub.val.idx
+#define strndmode sub.val.rndmode
 #define wstptr	sub.val.wsp
 #define wstlen	sub.val.wslen
 #ifdef HAVE_MPFR
@@ -1101,6 +1103,9 @@ extern char *OFMT;
 extern char *CONVFMT;
 extern int CONVFMTidx;
 extern int OFMTidx;
+#ifdef HAVE_MPFR
+extern int MPFR_round_mode;
+#endif
 extern char *TEXTDOMAIN;
 extern NODE *BINMODE_node, *CONVFMT_node, *FIELDWIDTHS_node, *FILENAME_node;
 extern NODE *FNR_node, *FS_node, *IGNORECASE_node, *NF_node;
@@ -1856,14 +1861,20 @@ dupnode(NODE *n)
  * and OFMT values. But if the value entered gawk as a string or strnum, then
  * stfmt should be set to STFMT_UNUSED, and the string representation should
  * not change.
+ *
+ * Additional twist: If ROUNDMODE changed at some point we have to
+ * recompute also.
  */
 
 static inline NODE *
 force_string_fmt(NODE *s, const char *fmtstr, int fmtidx)
 {
 	if ((s->flags & STRCUR) != 0
-		    && (s->stfmt == STFMT_UNUSED || s->stfmt == fmtidx)
-	)
+		&& (s->stfmt == STFMT_UNUSED || (s->stfmt == fmtidx
+#ifdef HAVE_MPFR
+						&& s->strndmode == MPFR_round_mode
+#endif
+				)))
 		return s;
 	return format_val(fmtstr, fmtidx, s);
 }
diff --git a/awkgram.c b/awkgram.c
index 3bc19645..52821eab 100644
--- a/awkgram.c
+++ b/awkgram.c
@@ -8771,6 +8771,9 @@ set_profile_text(NODE *n, const char *str, size_t len)
 		// Thanks and a tip of the hatlo to valgrind.
 		n->flags |= (NUMCONSTSTR|STRCUR);
 		n->stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+		n->strndmode = MPFR_round_mode;
+#endif
 	}
 
 	return n;
diff --git a/awkgram.y b/awkgram.y
index bbc598dd..ad830a5d 100644
--- a/awkgram.y
+++ b/awkgram.y
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 1986, 1988, 1989, 1991-2018 the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -6351,6 +6351,9 @@ set_profile_text(NODE *n, const char *str, size_t len)
 		// Thanks and a tip of the hatlo to valgrind.
 		n->flags |= (NUMCONSTSTR|STRCUR);
 		n->stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+		n->strndmode = MPFR_round_mode;
+#endif
 	}
 
 	return n;
diff --git a/builtin.c b/builtin.c
index fc948276..54d202d6 100644
--- a/builtin.c
+++ b/builtin.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 1986, 1988, 1989, 1991-2018 the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -2242,10 +2242,9 @@ do_print(int nargs, int redirtype)
 				DEREF(args_array[i]);
 			fatal(_("attempt to use array `%s' in a scalar context"), array_vname(tmp));
 		}
-		if (   (tmp->flags & STRCUR) == 0
-		    || (   tmp->stfmt != STFMT_UNUSED
-		        && tmp->stfmt != OFMTidx))
-			args_array[i] = force_string_ofmt(tmp);
+		// Let force_string_ofmt handle checking if things
+		// are already valid.
+		args_array[i] = force_string_ofmt(tmp);
 	}
 
 	if (redir_exp != NULL) {
diff --git a/doc/ChangeLog b/doc/ChangeLog
index c675db61..9baa3641 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-02         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* gawktexi.in (Setting the rounding mode): Add a sidebar
+	with sample code (courtesy of <nethox@gmail.com>) to
+	demonstrate how ROUNDMODE affects number to string conversion.
+
 2017-12-28         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* texinfo.tex: Updated.
@@ -49,7 +55,7 @@
 
 2017-11-17         Arnold D. Robbins     <arnold@skeeve.com>
 
-	* gawktexi.in(Changes from API V1): Give a list of things
+	* gawktexi.in (Changes from API V1): Give a list of things
 	that changed, with xrefs. Thanks to Andrew Schorr for the push.
 
 2017-11-09         Arnold D. Robbins     <arnold@skeeve.com>
diff --git a/doc/gawk.info b/doc/gawk.info
index 68aa1848..b42f26e5 100644
--- a/doc/gawk.info
+++ b/doc/gawk.info
@@ -23137,6 +23137,25 @@ cause any accumulating round-off error to cancel itself out.  This is
 the default rounding mode for IEEE 754 computing functions and
 operators.
 
+                     Rounding Modes and Conversion
+
+   It's important to understand that, along with 'CONVFMT' and 'OFMT',
+the rounding mode affects how numbers are converted to strings.  For
+example, consider the following program:
+
+     BEGIN {
+         pi = 3.1416
+         OFMT = "%.f"        # Print value as integer
+         print pi            # ROUNDMODE = "N" by default.
+         ROUNDMODE = "U"     # Now change ROUNDMODE
+         print pi
+     }
+
+Running this program produces this output:
+
+     $ gawk -M -f roundmode.awk
+     -| 3
+     -| 4
    The other rounding modes are rarely used.  Rounding toward positive
 infinity ('roundTowardPositive') and toward negative infinity
 ('roundTowardNegative') are often used to implement interval arithmetic,
@@ -35423,6 +35442,8 @@ Index
 * round() user-defined function:         Round Function.      (line  16)
 * rounding numbers:                      Round Function.      (line   6)
 * ROUNDMODE variable:                    User-modified.       (line 131)
+* ROUNDMODE variable <1>:                Setting the rounding mode.
+                                                              (line   6)
 * RS variable:                           awk split records.   (line  12)
 * RS variable <1>:                       User-modified.       (line 136)
 * RS variable, multiline records and:    Multiple Line.       (line  17)
@@ -35550,6 +35571,8 @@ Index
 * sidebar, Pre-POSIX awk Used OFMT for String Conversion: Strings And Numbers.
                                                               (line  54)
 * sidebar, Recipe for a Programming Language: History.        (line   6)
+* sidebar, Rounding Modes and Conversion: Setting the rounding mode.
+                                                              (line  65)
 * sidebar, RS = "\0" Is Not Portable:    gawk split records.  (line  63)
 * sidebar, So Why Does gawk Have BEGINFILE and ENDFILE?: Filetrans Function.
                                                               (line  83)
@@ -36375,160 +36398,160 @@ Node: Setting precision933040
 Ref: table-predefined-precision-strings933737
 Node: Setting the rounding mode935567
 Ref: table-gawk-rounding-modes935941
-Ref: Setting the rounding mode-Footnote-1939316
-Node: Arbitrary Precision Integers939495
-Ref: Arbitrary Precision Integers-Footnote-1942670
-Node: Checking for MPFR942819
-Node: POSIX Floating Point Problems944116
-Ref: POSIX Floating Point Problems-Footnote-1947987
-Node: Floating point summary948025
-Node: Dynamic Extensions950215
-Node: Extension Intro951768
-Node: Plugin License953034
-Node: Extension Mechanism Outline953831
-Ref: figure-load-extension954270
-Ref: figure-register-new-function955835
-Ref: figure-call-new-function956927
-Node: Extension API Description958989
-Node: Extension API Functions Introduction960631
-Node: General Data Types966171
-Ref: General Data Types-Footnote-1974532
-Node: Memory Allocation Functions974831
-Ref: Memory Allocation Functions-Footnote-1979041
-Node: Constructor Functions979140
-Node: Registration Functions982726
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-Node: Exit Callback Functions988626
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-Node: Output Wrappers1003260
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-Node: Requesting Values1012100
-Ref: table-value-types-returned1012837
-Node: Accessing Parameters1013773
-Node: Symbol Table Access1015008
-Node: Symbol table by name1015520
-Node: Symbol table by cookie1017309
-Ref: Symbol table by cookie-Footnote-11021494
-Node: Cached values1021558
-Ref: Cached values-Footnote-11025094
-Node: Array Manipulation1025247
-Ref: Array Manipulation-Footnote-11026338
-Node: Array Data Types1026375
-Ref: Array Data Types-Footnote-11029033
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-Node: Flattening Arrays1033623
-Node: Creating Arrays1040599
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-Node: Extension Sample Readfile1099803
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-Node: SVR41114202
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-Node: BTL1117016
-Node: POSIX/GNU1117745
-Node: Feature History1123523
-Node: Common Extensions1139382
-Node: Ranges and Locales1140665
-Ref: Ranges and Locales-Footnote-11145281
-Ref: Ranges and Locales-Footnote-21145308
-Ref: Ranges and Locales-Footnote-31145543
-Node: Contributors1145764
-Node: History summary1151709
-Node: Installation1153089
-Node: Gawk Distribution1154033
-Node: Getting1154517
-Node: Extracting1155480
-Node: Distribution contents1157118
-Node: Unix Installation1163598
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-Node: Shell Startup Files1166694
-Node: Additional Configuration Options1167783
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-Node: PC Using1175295
-Node: Cygwin1178340
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-Ref: Old Extension Problems-Footnote-11230191
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-Ref: Basic High Level-Footnote-11244644
-Node: Basic Data Typing1244829
-Node: Glossary1248157
-Node: Copying1279995
-Node: GNU Free Documentation License1317534
-Node: Index1342652
+Ref: Setting the rounding mode-Footnote-1939871
+Node: Arbitrary Precision Integers940050
+Ref: Arbitrary Precision Integers-Footnote-1943225
+Node: Checking for MPFR943374
+Node: POSIX Floating Point Problems944671
+Ref: POSIX Floating Point Problems-Footnote-1948542
+Node: Floating point summary948580
+Node: Dynamic Extensions950770
+Node: Extension Intro952323
+Node: Plugin License953589
+Node: Extension Mechanism Outline954386
+Ref: figure-load-extension954825
+Ref: figure-register-new-function956390
+Ref: figure-call-new-function957482
+Node: Extension API Description959544
+Node: Extension API Functions Introduction961186
+Node: General Data Types966726
+Ref: General Data Types-Footnote-1975087
+Node: Memory Allocation Functions975386
+Ref: Memory Allocation Functions-Footnote-1979596
+Node: Constructor Functions979695
+Node: Registration Functions983281
+Node: Extension Functions983966
+Node: Exit Callback Functions989181
+Node: Extension Version String990431
+Node: Input Parsers991094
+Node: Output Wrappers1003815
+Node: Two-way processors1008327
+Node: Printing Messages1010592
+Ref: Printing Messages-Footnote-11011763
+Node: Updating ERRNO1011916
+Node: Requesting Values1012655
+Ref: table-value-types-returned1013392
+Node: Accessing Parameters1014328
+Node: Symbol Table Access1015563
+Node: Symbol table by name1016075
+Node: Symbol table by cookie1017864
+Ref: Symbol table by cookie-Footnote-11022049
+Node: Cached values1022113
+Ref: Cached values-Footnote-11025649
+Node: Array Manipulation1025802
+Ref: Array Manipulation-Footnote-11026893
+Node: Array Data Types1026930
+Ref: Array Data Types-Footnote-11029588
+Node: Array Functions1029680
+Node: Flattening Arrays1034178
+Node: Creating Arrays1041154
+Node: Redirection API1045921
+Node: Extension API Variables1048754
+Node: Extension Versioning1049465
+Ref: gawk-api-version1049894
+Node: Extension GMP/MPFR Versioning1051625
+Node: Extension API Informational Variables1053253
+Node: Extension API Boilerplate1054326
+Node: Changes from API V11058300
+Node: Finding Extensions1059872
+Node: Extension Example1060431
+Node: Internal File Description1061229
+Node: Internal File Ops1065309
+Ref: Internal File Ops-Footnote-11076660
+Node: Using Internal File Ops1076800
+Ref: Using Internal File Ops-Footnote-11079183
+Node: Extension Samples1079457
+Node: Extension Sample File Functions1080986
+Node: Extension Sample Fnmatch1088635
+Node: Extension Sample Fork1090122
+Node: Extension Sample Inplace1091340
+Node: Extension Sample Ord1094557
+Node: Extension Sample Readdir1095393
+Ref: table-readdir-file-types1096282
+Node: Extension Sample Revout1097087
+Node: Extension Sample Rev2way1097676
+Node: Extension Sample Read write array1098416
+Node: Extension Sample Readfile1100358
+Node: Extension Sample Time1101453
+Node: Extension Sample API Tests1102801
+Node: gawkextlib1103293
+Node: Extension summary1105749
+Node: Extension Exercises1109451
+Node: Language History1110949
+Node: V7/SVR3.11112605
+Node: SVR41114757
+Node: POSIX1116191
+Node: BTL1117571
+Node: POSIX/GNU1118300
+Node: Feature History1124078
+Node: Common Extensions1139937
+Node: Ranges and Locales1141220
+Ref: Ranges and Locales-Footnote-11145836
+Ref: Ranges and Locales-Footnote-21145863
+Ref: Ranges and Locales-Footnote-31146098
+Node: Contributors1146319
+Node: History summary1152264
+Node: Installation1153644
+Node: Gawk Distribution1154588
+Node: Getting1155072
+Node: Extracting1156035
+Node: Distribution contents1157673
+Node: Unix Installation1164153
+Node: Quick Installation1164835
+Node: Shell Startup Files1167249
+Node: Additional Configuration Options1168338
+Node: Configuration Philosophy1170631
+Node: Non-Unix Installation1173000
+Node: PC Installation1173460
+Node: PC Binary Installation1174298
+Node: PC Compiling1174733
+Node: PC Using1175850
+Node: Cygwin1178895
+Node: MSYS1179665
+Node: VMS Installation1180166
+Node: VMS Compilation1180957
+Ref: VMS Compilation-Footnote-11182186
+Node: VMS Dynamic Extensions1182244
+Node: VMS Installation Details1183929
+Node: VMS Running1186182
+Node: VMS GNV1190461
+Node: VMS Old Gawk1191196
+Node: Bugs1191667
+Node: Bug address1192330
+Node: Usenet1195122
+Node: Maintainers1195899
+Node: Other Versions1197160
+Node: Installation summary1203922
+Node: Notes1205124
+Node: Compatibility Mode1205989
+Node: Additions1206771
+Node: Accessing The Source1207696
+Node: Adding Code1209133
+Node: New Ports1215352
+Node: Derived Files1219840
+Ref: Derived Files-Footnote-11225486
+Ref: Derived Files-Footnote-21225521
+Ref: Derived Files-Footnote-31226119
+Node: Future Extensions1226233
+Node: Implementation Limitations1226891
+Node: Extension Design1228074
+Node: Old Extension Problems1229228
+Ref: Old Extension Problems-Footnote-11230746
+Node: Extension New Mechanism Goals1230803
+Ref: Extension New Mechanism Goals-Footnote-11234167
+Node: Extension Other Design Decisions1234356
+Node: Extension Future Growth1236469
+Node: Old Extension Mechanism1237305
+Node: Notes summary1239068
+Node: Basic Concepts1240250
+Node: Basic High Level1240931
+Ref: figure-general-flow1241213
+Ref: figure-process-flow1241898
+Ref: Basic High Level-Footnote-11245199
+Node: Basic Data Typing1245384
+Node: Glossary1248712
+Node: Copying1280550
+Node: GNU Free Documentation License1318089
+Node: Index1343207
 
 End Tag Table
diff --git a/doc/gawk.texi b/doc/gawk.texi
index f0a0c26d..3ee8d042 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -32028,6 +32028,7 @@ $ @kbd{gawk -M 'BEGIN @{ PREC = 113; printf("%0.25f\n", 1/10) @}'}
 @node Setting the rounding mode
 @subsection Setting the Rounding Mode
 
+@cindex @code{ROUNDMODE} variable
 The @code{ROUNDMODE} variable provides
 program-level control over the rounding mode.
 The correspondence between @code{ROUNDMODE} and the IEEE
@@ -32100,6 +32101,70 @@ distributes upward and downward rounds of exact halves, which might
 cause any accumulating round-off error to cancel itself out. This is the
 default rounding mode for IEEE 754 computing functions and operators.
 
+@c January 2018. Thanks to nethox@gmail.com for the example.
+@cindex sidebar, Rounding Modes and Conversion
+@ifdocbook
+@docbook
+<sidebar><title>Rounding Modes and Conversion</title>
+@end docbook
+
+It's important to understand that, along with @code{CONVFMT} and
+@code{OFMT}, the rounding mode affects how numbers are converted to strings.
+For example, consider the following program:
+
+@example
+BEGIN @{
+    pi = 3.1416
+    OFMT = "%.f"        # Print value as integer
+    print pi            # ROUNDMODE = "N" by default.
+    ROUNDMODE = "U"     # Now change ROUNDMODE
+    print pi
+@}
+@end example
+
+@noindent
+Running this program produces this output:
+
+@example
+$ @kbd{gawk -M -f roundmode.awk}
+@print{} 3
+@print{} 4
+@end example
+
+@docbook
+</sidebar>
+@end docbook
+@end ifdocbook
+
+@ifnotdocbook
+@cartouche
+@center @b{Rounding Modes and Conversion}
+
+
+It's important to understand that, along with @code{CONVFMT} and
+@code{OFMT}, the rounding mode affects how numbers are converted to strings.
+For example, consider the following program:
+
+@example
+BEGIN @{
+    pi = 3.1416
+    OFMT = "%.f"        # Print value as integer
+    print pi            # ROUNDMODE = "N" by default.
+    ROUNDMODE = "U"     # Now change ROUNDMODE
+    print pi
+@}
+@end example
+
+@noindent
+Running this program produces this output:
+
+@example
+$ @kbd{gawk -M -f roundmode.awk}
+@print{} 3
+@print{} 4
+@end example
+@end cartouche
+@end ifnotdocbook
 The other rounding modes are rarely used.  Rounding toward positive infinity
 (@code{roundTowardPositive}) and toward negative infinity
 (@code{roundTowardNegative}) are often used to implement interval
diff --git a/doc/gawktexi.in b/doc/gawktexi.in
index a7406d62..d2325305 100644
--- a/doc/gawktexi.in
+++ b/doc/gawktexi.in
@@ -31041,6 +31041,7 @@ $ @kbd{gawk -M 'BEGIN @{ PREC = 113; printf("%0.25f\n", 1/10) @}'}
 @node Setting the rounding mode
 @subsection Setting the Rounding Mode
 
+@cindex @code{ROUNDMODE} variable
 The @code{ROUNDMODE} variable provides
 program-level control over the rounding mode.
 The correspondence between @code{ROUNDMODE} and the IEEE
@@ -31113,6 +31114,31 @@ distributes upward and downward rounds of exact halves, which might
 cause any accumulating round-off error to cancel itself out. This is the
 default rounding mode for IEEE 754 computing functions and operators.
 
+@c January 2018. Thanks to nethox@gmail.com for the example.
+@sidebar Rounding Modes and Conversion
+It's important to understand that, along with @code{CONVFMT} and
+@code{OFMT}, the rounding mode affects how numbers are converted to strings.
+For example, consider the following program:
+
+@example
+BEGIN @{
+    pi = 3.1416
+    OFMT = "%.f"        # Print value as integer
+    print pi            # ROUNDMODE = "N" by default.
+    ROUNDMODE = "U"     # Now change ROUNDMODE
+    print pi
+@}
+@end example
+
+@noindent
+Running this program produces this output:
+
+@example
+$ @kbd{gawk -M -f roundmode.awk}
+@print{} 3
+@print{} 4
+@end example
+@end sidebar
 The other rounding modes are rarely used.  Rounding toward positive infinity
 (@code{roundTowardPositive}) and toward negative infinity
 (@code{roundTowardNegative}) are often used to implement interval
diff --git a/field.c b/field.c
index 5263cc61..0d7e6330 100644
--- a/field.c
+++ b/field.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 1986, 1988, 1989, 1991-2018 the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -308,6 +308,9 @@ set_record(const char *buf, int cnt, const awk_fieldwidth_info_t *fw)
 	n->valref = 1;
 	n->type = Node_val;
 	n->stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+	n->strndmode = MPFR_round_mode;
+#endif
 	n->flags = (STRING|STRCUR|USER_INPUT);	/* do not set MALLOC */
 	fields_arr[0] = n;
 	if (fw != api_fw) {
diff --git a/gawkapi.c b/gawkapi.c
index f8964db2..80d3ebca 100644
--- a/gawkapi.c
+++ b/gawkapi.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 2012-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 2012-2018 the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -925,6 +925,9 @@ api_sym_update_scalar(awk_ext_id_t id,
 			r->stfmt = STFMT_UNUSED;
 			r->stptr = value->str_value.str;
 			r->stlen = value->str_value.len;
+#ifdef HAVE_MPFR
+			r->strndmode = MPFR_round_mode;
+#endif
 			return awk_true;
 		}
 		break;
diff --git a/interpret.h b/interpret.h
index 4b140c28..2ee68112 100644
--- a/interpret.h
+++ b/interpret.h
@@ -3,7 +3,7 @@
  */
 
 /* 
- * Copyright (C) 1986, 1988, 1989, 1991-2017 the Free Software Foundation, Inc.
+ * Copyright (C) 1986, 1988, 1989, 1991-2018 the Free Software Foundation, Inc.
  * 
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -735,6 +735,9 @@ mod:
 				/* configure as a string as in make_str_node */
 				t1->flags |= (MALLOC|STRING|STRCUR);
 				t1->stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+				t1->strndmode = MPFR_round_mode;
+#endif
 
 				if ((t1->flags & WSTRCUR) != 0 && (t2->flags & WSTRCUR) != 0) {
 					size_t wlen = t1->wstlen + t2->wstlen;
diff --git a/mpfr.c b/mpfr.c
index b9208a6b..1c4a2b9b 100644
--- a/mpfr.c
+++ b/mpfr.c
@@ -3,7 +3,8 @@
  */
 
 /*
- * Copyright (C) 2012, 2013, 2015, 2017, the Free Software Foundation, Inc.
+ * Copyright (C) 2012, 2013, 2015, 2017, 2018,
+ * the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
  * AWK Programming Language.
@@ -27,6 +28,8 @@
 
 #ifdef HAVE_MPFR
 
+int MPFR_round_mode = 'N';	// default value
+
 #if !defined(MPFR_VERSION_MAJOR) || MPFR_VERSION_MAJOR < 3
 typedef mp_exp_t mpfr_exp_t;
 #endif
@@ -373,6 +376,7 @@ mpg_format_val(const char *format, int index, NODE *s)
 		efree(s->stptr);
 	s->stptr = r->stptr;
 	s->flags |= STRCUR;
+	s->strndmode = MPFR_round_mode;
 	freenode(r);	/* Do not unref(r)! We want to keep s->stptr == r->stpr.  */
 	free_wstr(s);
 	return s;
@@ -596,6 +600,7 @@ set_ROUNDMODE()
 		if (rndm != -1) {
 			mpfr_set_default_rounding_mode(rndm);
 			ROUND_MODE = rndm;
+			MPFR_round_mode = n->stptr[0];
 		} else
 			warning(_("RNDMODE value `%.*s' is invalid"), (int) n->stlen, n->stptr);
 	}
diff --git a/node.c b/node.c
index f64bd9eb..add959f7 100644
--- a/node.c
+++ b/node.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2001, 2003-2015, 2017,
+ * Copyright (C) 1986, 1988, 1989, 1991-2001, 2003-2015, 2017, 2018,
  * the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
@@ -252,6 +252,9 @@ r_format_val(const char *format, int index, NODE *s)
 		if ((s->flags & (MALLOC|STRCUR)) == (MALLOC|STRCUR))
 			efree(s->stptr);
 		s->stptr = r->stptr;
+#ifdef HAVE_MPFR
+		s->strndmode = MPFR_round_mode;
+#endif
 		freenode(r);	/* Do not unref(r)! We want to keep s->stptr == r->stpr.  */
 
 		goto no_malloc;
@@ -273,6 +276,9 @@ r_format_val(const char *format, int index, NODE *s)
 			s->flags &= ~(INTIND|NUMBER);
 			s->flags |= STRING;
 		}
+#ifdef HAVE_MPFR
+		s->strndmode = MPFR_round_mode;
+#endif
 	}
 	if ((s->flags & (MALLOC|STRCUR)) == (MALLOC|STRCUR))
 		efree(s->stptr);
@@ -377,6 +383,9 @@ make_str_node(const char *s, size_t len, int flags)
 	r->flags = (MALLOC|STRING|STRCUR);
 	r->valref = 1;
 	r->stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+	r->strndmode = MPFR_round_mode;
+#endif
 	r->wstptr = NULL;
 	r->wstlen = 0;
 
diff --git a/str_array.c b/str_array.c
index 8d6d2b01..bc6584d2 100644
--- a/str_array.c
+++ b/str_array.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2013, 2016, 2017,
+ * Copyright (C) 1986, 1988, 1989, 1991-2013, 2016, 2017, 2018,
  * the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
@@ -444,7 +444,7 @@ str_kilobytes(NODE *symbol)
 
 	bucket_cnt = symbol->table_size;
 
-	/* This does not include extra memory for indices with stfmt != -1 */
+	/* This does not include extra memory for indices with stfmt != STFMT_UNUSED */
 	kb = (((AWKNUM) bucket_cnt) * sizeof (BUCKET) +
 		((AWKNUM) symbol->array_size) * sizeof (BUCKET *)) / 1024.0;
 	return kb;
diff --git a/symbol.c b/symbol.c
index 55b17397..797b5ec4 100644
--- a/symbol.c
+++ b/symbol.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 1986, 1988, 1989, 1991-2015, 2017,
+ * Copyright (C) 1986, 1988, 1989, 1991-2015, 2017, 2018,
  * the Free Software Foundation, Inc.
  *
  * This file is part of GAWK, the GNU implementation of the
@@ -653,6 +653,9 @@ check_param_names(void)
 	n.type = Node_val;
 	n.flags = STRING|STRCUR;
 	n.stfmt = STFMT_UNUSED;
+#ifdef HAVE_MPFR
+	n.strndmode = MPFR_round_mode;
+#endif
 
 	/*
 	 * assoc_list() returns an array with two elements per awk array
diff --git a/test/ChangeLog b/test/ChangeLog
index 1e1cf7ea..c64dc5bc 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,10 @@
+2018-01-02         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Thanks to Nethox <nethox@gmail.com> for this test.
+
+	* Makefile.am (mpfrrndeval): New test. 
+	* mpfrrndeval.awk, mpfrrndeval.ok: New files.
+
 2017-11-14         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* Makefile.am (EXTRA_DIST): Add new tests setrec0 and setrec1.
diff --git a/test/Makefile.am b/test/Makefile.am
index 1438e083..1ec63a20 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -666,6 +666,8 @@ EXTRA_DIST = \
 	mpfrrem.ok \
 	mpfrrnd.awk \
 	mpfrrnd.ok \
+	mpfrrndeval.awk \
+	mpfrrndeval.ok \
 	mpfrsort.awk \
 	mpfrsort.ok \
 	mpfrsqrt.awk \
@@ -1285,7 +1287,7 @@ INET_TESTS = inetdayu inetdayt inetechu inetecht
 
 MACHINE_TESTS = double1 double2 fmtspcl intformat
 
-MPFR_TESTS = mpfrnr mpfrnegzero mpfrmemok1 mpfrrem mpfrrnd mpfrieee
+MPFR_TESTS = mpfrnr mpfrnegzero mpfrmemok1 mpfrrem mpfrrnd mpfrrndeval mpfrieee
 	mpfrexprange mpfrsort mpfrsqrt mpfrbigint mpfrstrtonum mpgforcenum
 
 LOCALE_CHARSET_TESTS = \
@@ -2073,6 +2075,11 @@ mpfrrnd:
 	@$(AWK) -M -vPREC=53 -f "$(srcdir)"/$@.awk > _$@ 2>&1
 	@-$(CMP) "$(srcdir)"/$@.ok _$@ && rm -f _$@
 
+mpfrrndeval:
+	@echo $@
+	@$(AWK) -M -f "$(srcdir)"/$@.awk > _$@ 2>&1
+	@-$(CMP) "$(srcdir)"/$@.ok _$@ && rm -f _$@
+
 mpfrnegzero:
 	@echo $@
 	@$(AWK) -M -f "$(srcdir)"/$@.awk > _$@ 2>&1
diff --git a/test/Makefile.in b/test/Makefile.in
index 5a190d7a..9775fd5b 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -924,6 +924,8 @@ EXTRA_DIST = \
 	mpfrrem.ok \
 	mpfrrnd.awk \
 	mpfrrnd.ok \
+	mpfrrndeval.awk \
+	mpfrrndeval.ok \
 	mpfrsort.awk \
 	mpfrsort.ok \
 	mpfrsqrt.awk \
@@ -1538,7 +1540,7 @@ ARRAYDEBUG_TESTS = arrdbg
 EXTRA_TESTS = inftest regtest ignrcas3 
 INET_TESTS = inetdayu inetdayt inetechu inetecht
 MACHINE_TESTS = double1 double2 fmtspcl intformat
-MPFR_TESTS = mpfrnr mpfrnegzero mpfrmemok1 mpfrrem mpfrrnd mpfrieee
+MPFR_TESTS = mpfrnr mpfrnegzero mpfrmemok1 mpfrrem mpfrrnd mpfrrndeval mpfrieee
 LOCALE_CHARSET_TESTS = \
 	asort asorti backbigs1 backsmalls1 backsmalls2 \
 	fmttest fnarydel fnparydl jarebug lc_num1 mbfw1 \
@@ -2512,6 +2514,11 @@ mpfrrnd:
 	@$(AWK) -M -vPREC=53 -f "$(srcdir)"/$@.awk > _$@ 2>&1
 	@-$(CMP) "$(srcdir)"/$@.ok _$@ && rm -f _$@
 
+mpfrrndeval:
+	@echo $@
+	@$(AWK) -M -f "$(srcdir)"/$@.awk > _$@ 2>&1
+	@-$(CMP) "$(srcdir)"/$@.ok _$@ && rm -f _$@
+
 mpfrnegzero:
 	@echo $@
 	@$(AWK) -M -f "$(srcdir)"/$@.awk > _$@ 2>&1
diff --git a/test/mpfrrndeval.awk b/test/mpfrrndeval.awk
new file mode 100644
index 00000000..12010052
--- /dev/null
+++ b/test/mpfrrndeval.awk
@@ -0,0 +1,35 @@
+# Tests side effects (like caching) on the evaluation (formatting and
+# rounding) of MPFR variables vs literals.
+BEGIN {
+	pi = 3.1416
+	e = 2.7183
+	golden = 1.6180
+
+	# Evaluated as number with (default) OFMT.
+	print pi
+	print e
+	print golden
+	printf "\n"
+
+	# Evaluated as number with (custom) OFMT.
+	OFMT = "%.f"
+	ROUNDMODE = "U";  print "Variable pi U:", pi
+	ROUNDMODE = "D";  print "Variable pi D:", pi
+	ROUNDMODE = "U";  print "Literal  pi U:", 3.1416
+	ROUNDMODE = "D";  print "Literal  pi D:", 3.1416
+	printf "\n"
+
+	# Evaluated as string with (custom) CONVFMT. Absent comma.
+	CONVFMT = "%.f"
+	ROUNDMODE = "D";  print "Variable e D: " e
+	ROUNDMODE = "U";  print "Variable e U: " e
+	ROUNDMODE = "D";  print "Literal  e D: " 2.7183
+	ROUNDMODE = "U";  print "Literal  e U: " 2.7183
+	printf "\n"
+
+	# Evaluated as number with (hardcoded) printf conversion.
+	ROUNDMODE = "N";  printf "Variable golden N: %.f\n", golden
+	ROUNDMODE = "Z";  printf "Variable golden Z: %.f\n", golden
+	ROUNDMODE = "N";  printf "Literal  golden N: %.f\n", 1.6180
+	ROUNDMODE = "Z";  printf "Literal  golden Z: %.f\n", 1.6180
+}
diff --git a/test/mpfrrndeval.ok b/test/mpfrrndeval.ok
new file mode 100644
index 00000000..034b21e0
--- /dev/null
+++ b/test/mpfrrndeval.ok
@@ -0,0 +1,18 @@
+3.1416
+2.7183
+1.618
+
+Variable pi U: 4
+Variable pi D: 3
+Literal  pi U: 4
+Literal  pi D: 3
+
+Variable e D: 2
+Variable e U: 3
+Literal  e D: 2
+Literal  e U: 3
+
+Variable golden N: 2
+Variable golden Z: 1
+Literal  golden N: 2
+Literal  golden Z: 1