From 043879980822bb15d4d580a2ce36b99f0c73fa83 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sun, 3 Oct 2021 13:29:58 -0700
Subject: expr: Use end pointer to detect string-to-number conversion failures

We explicitly ignore ERANGE for strtod, and in any other error case,
the end pointer is set to the beginning of the string.
---
 expr.c | 11 ++++-------
 qbe.c  |  1 -
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/expr.c b/expr.c
index 57ef471..19dd012 100644
--- a/expr.c
+++ b/expr.c
@@ -1,6 +1,5 @@
 #include <assert.h>
 #include <ctype.h>
-#include <errno.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -511,10 +510,9 @@ primaryexpr(struct scope *s)
 		base = tok.lit[0] != '0' ? 10 : tolower(tok.lit[1]) == 'x' ? 16 : 8;
 		if (strpbrk(tok.lit, base == 16 ? ".pP" : ".eE")) {
 			/* floating constant */
-			errno = 0;
 			e->constant.f = strtod(tok.lit, &end);
-			if (errno && errno != ERANGE)
-				error(&tok.loc, "invalid floating constant '%s': %s", tok.lit, strerror(errno));
+			if (end == tok.lit)
+				error(&tok.loc, "invalid floating constant '%s'", tok.lit);
 			if (!end[0])
 				e->type = &typedouble;
 			else if (tolower(end[0]) == 'f' && !end[1])
@@ -525,10 +523,9 @@ primaryexpr(struct scope *s)
 				error(&tok.loc, "invalid floating constant suffix '%s'", end);
 		} else {
 			/* integer constant */
-			errno = 0;
 			e->constant.u = strtoull(tok.lit, &end, 0);
-			if (errno)
-				error(&tok.loc, "invalid integer constant '%s': %s", tok.lit, strerror(errno));
+			if (end == tok.lit)
+				error(&tok.loc, "invalid integer constant '%s'", tok.lit);
 			e->type = inttype(e->constant.u, base == 10, end);
 		}
 		next();
diff --git a/qbe.c b/qbe.c
index a1f2773..50eb5eb 100644
--- a/qbe.c
+++ b/qbe.c
@@ -1,6 +1,5 @@
 #include <assert.h>
 #include <ctype.h>
-#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
-- 
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