d: Merge upstream dmd 423f19b41, druntime 100a608c, phobos a1f8c4c07.

D Runtime changes:

    - Fix stdc.stdio bindings to not depend on druntime (PR104729).
    - Implement stdc.math for Solaris (PR104735).

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 423f19b41.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime 100a608c.
	* src/MERGE: Merge upstream phobos a1f8c4c07.

3 files changed, 21 insertions, 57 deletions

diff --git a/libphobos/src/MERGE b/libphobos/src/MERGE
index e15541e181d..5fd357c534a 100644
--- a/libphobos/src/MERGE
+++ b/libphobos/src/MERGE
@@ -1,4 +1,4 @@
-41aaf8c2636df0e2e3ad39933b321d2b4cd231fa
+a1f8c4c0700ce4e256f4130ad7883c6ea3890901
 
 The first line of this file holds the git revision number of the last
 merge done from the dlang/phobos repository.
diff --git a/libphobos/src/std/datetime/systime.d b/libphobos/src/std/datetime/systime.d
index 9b2a8443fdd..db325f727e8 100644
--- a/libphobos/src/std/datetime/systime.d
+++ b/libphobos/src/std/datetime/systime.d
@@ -8713,13 +8713,14 @@ public:
 
     /++
         Creates a $(LREF SysTime) from a string with the format
-        YYYYMMDDTHHMMSS.FFFFFFFTZ (where F is fractional seconds is the time
-        zone). Whitespace is stripped from the given string.
+        YYYYMMDDTHHMMSS.FFFFFFFTZ (where F is fractional seconds and TZ
+        is the time zone). Whitespace is stripped from the given string.
 
-        The exact format is exactly as described in `toISOString` except that
-        trailing zeroes are permitted - including having fractional seconds with
-        all zeroes. However, a decimal point with nothing following it is
-        invalid. Also, while $(LREF toISOString) will never generate a string
+        The exact format is exactly as described in $(LREF toISOString) except
+        that trailing zeroes are permitted - including having fractional seconds
+        with all zeroes. The time zone and fractional seconds are optional,
+        however, a decimal point with nothing following it is invalid.
+        Also, while $(LREF toISOString) will never generate a string
         with more than 7 digits in the fractional seconds (because that's the
         limit with hecto-nanosecond precision), it will allow more than 7 digits
         in order to read strings from other sources that have higher precision
@@ -9024,13 +9025,14 @@ public:
 
     /++
         Creates a $(LREF SysTime) from a string with the format
-        YYYY-MM-DDTHH:MM:SS.FFFFFFFTZ (where F is fractional seconds is the
-        time zone). Whitespace is stripped from the given string.
+        YYYY-MM-DDTHH:MM:SS.FFFFFFFTZ (where F is fractional seconds and TZ
+        is the time zone). Whitespace is stripped from the given string.
 
-        The exact format is exactly as described in `toISOExtString`
+        The exact format is exactly as described in $(LREF toISOExtString)
         except that trailing zeroes are permitted - including having fractional
-        seconds with all zeroes. However, a decimal point with nothing following
-        it is invalid. Also, while $(LREF toISOExtString) will never generate a
+        seconds with all zeroes. The time zone and fractional seconds are
+        optional, however, a decimal point with nothing following it is invalid.
+        Also, while $(LREF toISOExtString) will never generate a
         string with more than 7 digits in the fractional seconds (because that's
         the limit with hecto-nanosecond precision), it will allow more than 7
         digits in order to read strings from other sources that have higher
@@ -9273,13 +9275,14 @@ public:
 
     /++
         Creates a $(LREF SysTime) from a string with the format
-        YYYY-MM-DD HH:MM:SS.FFFFFFFTZ (where F is fractional seconds is the
-        time zone). Whitespace is stripped from the given string.
+        YYYY-Mon-DD HH:MM:SS.FFFFFFFTZ (where F is fractional seconds and TZ
+        is the time zone). Whitespace is stripped from the given string.
 
-        The exact format is exactly as described in `toSimpleString` except
+        The exact format is exactly as described in $(LREF toSimpleString) except
         that trailing zeroes are permitted - including having fractional seconds
-        with all zeroes. However, a decimal point with nothing following it is
-        invalid. Also, while $(LREF toSimpleString) will never generate a
+        with all zeroes. The time zone and fractional seconds are optional,
+        however, a decimal point with nothing following it is invalid.
+        Also, while $(LREF toSimpleString) will never generate a
         string with more than 7 digits in the fractional seconds (because that's
         the limit with hecto-nanosecond precision), it will allow more than 7
         digits in order to read strings from other sources that have higher
diff --git a/libphobos/src/std/sumtype.d b/libphobos/src/std/sumtype.d
index 0dd636ea67b..3833c84243c 100644
--- a/libphobos/src/std/sumtype.d
+++ b/libphobos/src/std/sumtype.d
@@ -1569,27 +1569,7 @@ private enum bool isSumTypeInstance(T) = is(T == SumType!Args, Args...);
 }
 
 /// True if `T` is a [SumType] or implicitly converts to one, otherwise false.
-template isSumType(T)
-{
-    static if (is(T : SumType!Args, Args...))
-    {
-        enum isSumType = true;
-    }
-    else static if (is(T == struct) && __traits(getAliasThis, T).length > 0)
-    {
-        // Workaround for https://issues.dlang.org/show_bug.cgi?id=21975
-        import std.traits : ReturnType;
-
-        alias AliasThisType = ReturnType!((T t) =>
-            __traits(getMember, t, __traits(getAliasThis, T)[0])
-        );
-        enum isSumType = .isSumType!AliasThisType;
-    }
-    else
-    {
-        enum isSumType = false;
-    }
-}
+enum bool isSumType(T) = is(T : SumType!Args, Args...);
 
 ///
 @safe unittest
@@ -1610,25 +1590,6 @@ template isSumType(T)
     assert(!isSumType!ContainsSumType);
 }
 
-@safe unittest
-{
-    static struct AliasThisVar(T)
-    {
-        SumType!T payload;
-        alias payload this;
-    }
-
-    static struct AliasThisFunc(T)
-    {
-        SumType!T payload;
-        ref get() { return payload; }
-        alias get this;
-    }
-
-    static assert(isSumType!(AliasThisVar!int));
-    static assert(isSumType!(AliasThisFunc!int));
-}
-
 /**
  * Calls a type-appropriate function with the value held in a [SumType].
  *